LIFE
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SEA-SHORE
NEWBIGiN
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LIBRARY
UNIVERSITY OF CALIFORNIA.
BIOLOGY
LIBRARY
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LIFE BY THE SEASHORE
Jin Jtttr0tuixti0tt t0 Natural History
BY
MAKION NEWBIGIN, D.So. (LOND.)
LECTURER ON ZOOLOGY IN MEDICAL COLLEGE FOR WOMEN
EDINBURGH
AUTHOR OF "COLOUR IN NATURE"
WITH MANY ORIGINAL ILLUSTRATIONS BY
FLORENCE NEWBIGIN
LONDON
SWAN SOKNENSOHEIN & CO, LTD.
25 HIGH STREET, BLOOMSBURY
1907
OF THE
UNIVERSITY
SOME OPINIONS OF THE PRESS
"This little book is quite up to date, and although scientifically accurate
and sound, is so delightfully simple that it can be read and comprehended by
anyone at the seaside who can collect common shore animals and compare
them with the printed pages. It is a pleasure to cordially recommend Life by
the Seashore as a charming and useful holiday companion, which will not only
give much information, but Avill also serve as a good introduction to one of the
most fascinating branches of modern science." — Nature.
"The present work can safely claim to have justified its appearance, for it is
an exceedingly well written, and as far as it goes a very accurate account of
the majority of the common animals found between tide marks."
Journal of Queckett Microscopical Club.
" This is a good book. After reading even the first chapter, one feels that
Miss Newbigin knows and cares about her subject. The style and arrange-
ment of the book are excellent ; there are numerous illustrations, and at the
end of each chapter are tables of classification and a note on distribution
which should prove extremely useful."— Science Gossip.
" As an introduction- to natural history it is admirable, and as a companion
to a summer holiday by the sea it is invaluable."— Weymouth Journal.
First Published, 1901 : Reprinted, January, 1907
PEEFACE
book is largely based upon a series of lectures
on common shore animals, delivered at different
times to various audiences. Its object is to enable
those who have not had a special zoological training
to learn the names and characters of the common
inhabitants of the rock pools ; but it is hoped that
the subject has been treated from a sufficiently broad
standpoint to render the book also of value as a
general introduction to one of the most fascinating
branches of modern science. Special efforts have
been made to render the descriptions .sufficiently de-
tailed to ensure the identification of actual specimens,
and to assist the process by keys and tables. As this
detail naturally limits the number of species it is
possible to discuss, the book makes no attempt at
completeness. It treats chiefly of the common shore
forms of the East Coast, but this partiality is cor-
rected, first by notes on distribution, and second by a
list of books of reference, which will enable those
interested to pursue the subject further. In regard
to this list I may say that it has been limited to works
iy PREFACED
in the English language, and to those readily accessible
in the public libraries of our larger towns.
As to the difficult question of nomenclature, I
have in each group employed the names used in some
standard work, indicated in the list of books of
reference. Where these names are out of date a
reference is given to a source from which the modern
terminology can be learnt. Unless such valuable
books as Gosse's Sea- Anemones are to be rendered use-
less to the beginner, this seems the only possible
course in a popular book.
The figures, which I owe to my sister Miss Florence
Newbigin, have in many cases been drawn from actual
specimens; the source from which the others have
been obtained is indicated in the list of illustrations.
To my sister I am also indebted for the Index.
MEDICAL COLLEGE FOR WOMEN
EDINBURGH, June, 1901
CONTENTS.
CHAPTER PAGE
I. THE GENERAL CHARACTERISTICS OF SHORE ANIMALS 1
II. THE STUDY OF SHORE ANIMALS . . . 19
III. SPONGES, ZOOPHYTES, AND SEA-FIRS . ....... 36
IV. SEA- ANEMONES AND THEIR ALLIES . ... 64
V. THE BRISTLE-WORMS . . 82
VI. THE BRISTLE- WORMS (continued] . ;. . 104
VII. SEA-URCHINS, STARFISH, AND BHITTLE-STARS . 125
VIII. THE DECAPOD CRUSTACEA . * » . 150
IX. LOBSTERS, CRAYFISH, AND THEIR ALLIES . .171
X. THE TRUE CRABS . . . . 194
XI. SOME OTHER CRUSTACEA . ... 209
XII. MOLLUSCS, OR SHELL-FISH . ... 225
XIII. THE SEA-SLUGS . . ... 248
XIV. BIVALVES AND CUTTLES . ... 266
XV. FISHES AND SEA- SQUIRTS . . ..' . 290
XVI. THE DISTRIBUTION AND RELATIONS OF SHORE
ANIMALS . . , 317
SOME BOOKS OF REFERENCE . . . 332
INDEX 335
LIST OF FIGURES.
*iG F/.OK
1. Pholas crispata, a burrowing Mollusc « ; 8
2. Sand-laimce (Ammodytes tobianus). After Day . . 9
3. Hermit-crab and Hydr actinia. After All man . . 12
4. ZWo coronata. After Alder and Hancock . . . . 13
5. Dead Men's Fingers (Alcyonium digitatum) . . 16
6. Swimming-bell (Sarsia). After Allman . . . 17
7. Lump-sucker (Cyclopterus lumpus). After Day . . 21
8. Edible crab (Cancer pagurus) . . 26
9. Plumularia sctacea. After Hincks . . .29
10. Fisherman's lob-worm (Arenicola piscatorum) . . 30
11. Common scallop (I'ecten opercularis) . 31
12. Diagram of Hydractinia. After Allman . . .41
13. Clava squamata. After Allman . . .45
14. Syncoryne eximia. After Allman . 46
15. Sarsia, or swimming-bell. After Hincks . 47
16. Tubularia indivisa. After Allman . 49
17. Obelia geniculata. After Hincks . 51
18. Campanularia flexuosa (magnified). After Hincks . 52
19. Halecium halecinum (magnified). After Hincks . . 54
20. Sertularia pumila and branch magnified. After Hincks 55
21. Bottle-brush coralline (Thuiaria thuia). After Hincks 56
22. Plumularia (magnified branch). After Hincks . . 57
23. Common sea-anemone (Actinia mesembryanthemum) . 65
24. Tealia crassicornis. After Tugwell . . .68
25. Sagartia troglodytes . . . 70
26. Actinoloba dianthus. After Tugwell . 73
27. Haliclystus octoradiatus . . 78
28. Nereis pelagica . . . 84
29. Foot of Nereis pelagica. After Ehlers . .' . 86
30. Introvert of Nereis pelagica. After Lang . 87
vi
LIST OF FIGURES. vil*
FIG. PAOE
31. Dissection of Arenicola. In part after Gamble and
Ashworth . . . *.. . 92
32. Sthenelais boa, a sand Polynoid. After Johnston . . 97
33. Paddle-worm (Pkyllodoce lamelligerd) . 99
34. Head and introvert of paddle-worm. After Ehlers . 100
35. Introvert of Nereis pelagica to show teeth. After Ehlers 104
36. Foot of NepJithys hombergii. After Ehlers . . 109
37. Sand-mason (Terebella) removed from tube . . 113
38. Pectinaria belgica. After Malmgren . . . 115
39. Serpula vermicularis in tube . ... 117
40. Sea-snake (Linens marinus) . ... 121
41. Solaster papposus, or sun-star . . . 128
42. Common brittle-star (Opliiothrixfragilis) . . . 129
43. Disc of sand-star (Ophiura) . . . 130
44. Aristotle's lantern from sea-urchin . . .136
45. Sea-urchin (Echinus esculentus) . ... 138
46. Sea-cucumber (Cucumaria planci). After Bell. . . 144
47. Prawn (Palcemon squilld) ' . . . 151
48. Lobster (Homarus vulgaris) . ... 152
49. Shore crab (Carcinus manias') . ... 153
50. Foot-jaws of lobster and of crab . . .160
51. Scaly Galathea (Galathea squamifera) . . . 177
52. Hairy porcelain-crab (Porcellana platycheles) . .179
53. Hermit-crab (Pagurus bernhardus) » . . 184
54. Masked crab (Corystes cassivelaunus). In part after
Herbst . f . , "... 189
55. Spider-crab (Eyas araneus) . . . .197
56. Long-legged spider-crab (Stenorhynchus phalangium) . 198
57. Wrinkled swimming crab (Portunus depurator) . . 202
58. Megalopa of shore crab. After Brook . . . 206
59. Mysis stage of Norway lobster. After Sars . . 206
60. Opossum-shrimp (Mysis flexuosa) . . . 209
61. Head and tail of Mysis. After Bell . . .212
62. Idotea tricuspidata. In part from Bate and Westwood . 216
63. Gammarus locusta . - . . . .217
64. Caprella linearis . . . . . 218
65. Sea-spider (Pycnogonum littorale) . . . 221
66. Under surface of limpet (Patella) . . 226
67. Chiton marginatus . . ... 228
68. Tortoise-shell limpet (Acmcea testudinalis) . . 233
viii LIFE BY THE SEASHORE.
FIG. PAGE
69. Trochus zizyphinus . . ... 235
70. Common whelk (Buccinum undatum) ' » ' . . 244
71. Sea-hare (Aplysia hybrida). After Gosse . • , - .250
72. Doris johnstoni. After Alder and Hancock , . 252
73. Goniodoris nodosa. After Alder and Hancock . . 255.
74. Aneula cristata. After Alder and Hancock .. . 256
75. Spawn of Doto coronata. After Alder and Hancock . 259
76. Eolis rufibranchialis. After Alder and Hancock . .261
77. Common mussel (Mytilus edulis) » j . . 267
78. Tapes pullastra ., . ... 268
79. Shell of Cyprina island,ica . . . 279
80. Mactra stultorum .. . . . 280
81. Mya truncata . . ... 283
82. Kazor-shell (Solcn siliqua) . . . 284
83. Corella parallelogramma . ... 292
84. Polycarpa rustica . , . . 295
85. Saithe, or coal-fish (Gadus wrens). After Day . . 298
86. Sea-scorpion (Coitus scorpius). After Day . . 301
87. Common shanny (Blennius pholis). After Day . . 306
88. Gunnel (Centronotus gunnellus). After Day . . 308
89. Herring-bone coralline (Halecium halecinum). After
Hincks . . . ... 319
90. Swimming-bell of Clytia johnstoni. After Hincks . 326
91. Nauplius of Peneus. After Muller " . . .327
92. Zoea of crab ( Thia polita). After Claus . . . 328
93. Sea-gooseberry (Pleurolrachia) . ... . . 330
LIFE BY THE SEASHORE,
CHAPTEE I.
THE GENERAL CHARACTERISTICS OF SHORE
ANIMALS.
9>
Conditions of shore life — The abundant food-supply — The physical
conditions — Influence of the tides — The peculiarities of shore
animals — Passive means of protection — Shells and tubes — The
habit of burrowing — Protection against organic foes — Weapons of
offence and defence — Self-mutilation — Partnerships — Colour resem-
blances — Masking — Dangers of storms and floods — Means of dis-
tribution — Characters of young and larval forms.
are perhaps few localities where the extraordinary
_ abundance of life is more striking than on the seashore.
From the birds which circle and cry overhead to the count-
less myriads of sand-hoppers which spring up at every
footstep, there seems to be life everywhere, life in a careless
and wanton profusion the secret of which is known to the
sea alone. Nowhere else does one find animals in such
number and variety within a limited area. It is therefore
all the more remarkable that while so many people take an
interest in terrestrial animals, such as insects and land shells,
relatively so few are interested in marine animals, where the
field is so much wider, and the phenomena so much more
striking. For every person who could name a common
anemone there must be dozens who could name a common
butterfly, and this in a country not a little proud of its
encircling ocean. The opportunity for shore -hunting is
2 LIFE BY THE SEASHORE.
nowadays given to very many people for at least a few
weeks in every year, and even in this brief time it is
possible to acquire not a little knowledge of the ways and
structure of the common shore animals.
We shall not at present seek strictly to define the mean-
ing of the word "shore," but in beginning a preliminary
study of the conditions of shore life, may conveniently start
from that commonplace of observation, which shows that all
parts of the shore area are not equally productive. It is
true that wherever the ebbing tide leaves bare long stretches
of sand, there will be found some of the inhabitants of the
littoral waters, living or dead, according to the force of
the waves which have torn them from their rocky homes ;
but we all know that to find these animals in their natural
conditions we must forsake the sandy beach for the weed-
covered rocks. In order to understand why it is that the
majority of shore animals live in the vicinity of rocks, let us
watch what happens when some change of current uncovers
a ridge of rock hitherto concealed by the sand. We find
that the first organisms to appear are usually Algae of various
kinds, the coarser kinds being often the most obvious at
first. Then come acorn-shells and vegetable-eating Molluscs,
and as these thrive and multiply they are followed by car-
nivorous whelks, buckies, and starfishes. As the weeds
grow, crabs and other Crustaceans make their appearance,
and the new settlement thrives apace until it contains most
of the animals inhabiting the parent area. How the
animals reach the new area is a question to which we
shall return later; our special concern now is what deter-
mines the gradual colonisation, and why does it only occur
where there is a solid substratum of some kind? The
answer is simple; it is essentially a question of food, and
the food upon which shore animals depend is most abundant
in the vicinity of rocks.
Let us for a moment consider generally the food-supplies
of marine animals. The simplest case is probably that of
the pelagic animals, or those animals which live in the open
waters of the sea. These all depend ultimately either upon
the microscopic plants with which the water is filled, or
upon microscopic animals which because they contain green
colouring matter are able to feed like plants. The depend-
THE GENERAL CHARACTERISTICS OF SHORE ANIMALS. 3
ence is primary when, as in many pelagic worms, molluscs,
artd sea-squirts, the minute plants are actually taken as
food ; it is secondary when, as in many fish, the food
consists of the worms, molluscs, sea-squirts, etc., which
themselves feed upon the Algse. Abundantly supplied with
air and sunlight, the little plants grow and multiply rapidly,
and constitute the great basal food-supply of the animals of
the open sea.
Many of those minute plants, or plant-like animals, occur
also in the shallow shore waters, and there again constitute
an important part of the food-supply, but this is supple-
mented in two ways. First, we have an enormous amount
of material carried into the sea by rivers. It is a fact of
common experience that mudbanks of varying size usually
occur about the mouths of rivers. The constituent mud is
brought clown by the river, and it contains an abundant
supply of nutrient material, of which very many shore
animals avail themselves. Second, we have the large fixed
seaweeds, which can flourish only in water shallow enough
for the light to reach them, and which occur in great variety
and abundance around our shores wherever there are rocky
surfaces to which they can affix themselves.
According to their diet we may divide the shore animals
into three sets: (1) those which are vegetarian in habit,
living upon the large seaweeds ; (2) those which feed upon
minute food-particles contained in the water or in sand and
mud ; (3) those which are carnivorous and depend upon
the two preceding sets for food. All these three sets find
food most abundant in the vicinity of rocks. The first
obviously do so because the large seaweeds grow well only
when fixed to a solid base. It may not be quite so clear
why the statement is true of the second set, but it is a fact
that shore animals which feed on microscopic particles are
sedentary animals, not capable of resisting by their own
activity the force of shore currents and shore waves. In
consequence they usually cannot flourish unless, like the
shore weeds, they have a firm basis of attachment. The
chief exception arises in the case of burrowers which often
live in sand quite away from rocks. As the carnivorous
animals depend upon the preceding two sets, it is obvious
that they can abound only in the vicinity of the rocks
4 LIFE BY THE SEASHORE.
haunted by these. A little experience on the shore will
soon convince you that shore animals are not quite so
sharply differentiated from one another as regards food as
this description seems to suggest, for some forms seem to
indulge in a mixed diet; but at the same time it may be
helpful at first to look at the food-supply in this way.
So far we have seen that the shore area is above all
distinguished by its abundant food-supply, but it must not
be supposed on this account that life within this area is
necessarily easy. It is indeed rather the reverse that is
true. In the first place the abundant food-supply has led
to a great increase of population, and a consequent increase
in the intensity of the struggle for existence among the
shore animals, and in the second place the physical environ-
ment is so variable as to make heavy demands on the
adaptability of the organism. Look at the wreckage which
almost every tide strews upon the beach, and you will
realise how fierce is the struggle against inorganic nature
which goes on in the shore area.
Let us look for a little at the special peculiarities of the
physical environment of shore animals. Kound our coasts
one of the most striking of the natural phenomena of the
littoral region is the daily ebb and flow of the tide. Twice
in each twenty-four hours the waters retreat and leave bare
a great stretch of the shore, twice they return, the breakers
thundering on the rocks as they advance. As everyone
who has had anything to do with the sea knows well, not
only does the extent of the rise vary according to the locality,
but for the same locality it varies from day to day. Twice
in every lunar month occurs the phenomenon of spring tides,
when the water rises to an unusual height and sinks to a
correspondingly low level. Even these spring tides are,
however, not constant, certain tides in spring and autumn
rising to a much greater height than the ordinary springs.
Later, we shall discuss the importance of these facts to the
naturalist, at present we are concerned merely with their
importance to the shallow-water animals. The shore area is
populated by truly marine animals from high-tide mark
downwards ; indeed, certain periwinkles seem to live above
the level of all but the highest spring tides. If we begin
with these hardy forms and pass downwards to the region
THE GENERAL CHARACTERISTICS OF SHORE ANIMALS. 5
which is uncovered only at the lowest springs, we find a
complete series of gradations in regard to exposure to air.
The periwinkles mentioned are really under water only for
a brief period daily, during perhaps a few days every six
months. Then we may have other forms which are covered
by water only for a short time at spring tides, and so on
down to the animals which are wwcovered only for a brief
period during the very lowest spring?. But, as all seafaring
people know, the times and heights of the tides as indicated
in the calculated tables are in many localities liable to
considerable variation on account of winds and storms, so
that one must? beware of ascribing too great constancy to
tidal movements. All the animals which belong to the
shore area, with a few exceptions which need not concern
us here, breathe air dissolved in water, so that the fact that
they are periodically exposed to the action of the atmosphere,
necessitates special means of protection for the delicate
breathing organs. The amount of protection required must
necessarily vary with the amount of exposure.
The risk of injury to the breathing organs is not the only
danger to which the ebb of the tide exposes shore animals,
for the removal of the water makes feeding impossible to
not a few of them, and it also exposes them to variations of
temperature — the frosts of winter and the sun of summer —
and to the keen eyes of the birds which flock to the rocks
as the tide ebbs. Furthermore, as the water returns its
waves batter furiously against the rocks and their denizens,
so that these have manifold dangers to guard against.
Among the general characters of shore animals we should
thus expect to find that they usually possess some means of
protection against the risk of exposure to the atmc sphere,
with the correlated risks of freezing or drying up, and
also against the force of the waves, which tend to tear
them away from their rocky homes. In point of fact, we
do find that shore animals show many adaptations to these
conditions of shore life. In the first place, very many of
them possess shells into which the animal can retire, and
which serve to protect it against variations of temperature
and the risk of drying up. Shells are especially character-
istic of the greater number of the Mollusca, or " shellfish "
par excellence, but are also possessed by not a few other
6 LIFE BY THE SEASHORE.
animals. Thus some worms, like Serpula and Spirorbis, make
white limy tubes and shells into which the whole body can
be retracted. The acorn-shells, which are often the common-
est of all animals on the shore rocks, are Crustacea which
secrete a limy shell into which the whole animal can be
withdrawn, and which can then be closed to prevent evapora-
tion of moisture. In these cases, however, the animals are
completely sedentary, never moving from the place where
they have settled down in youth, and from their size and
shape offering little opportunity to the waves. It is other-
wise with the Molluscs, which frequently possess consider-
able power of movement, and have, as it were, to consider
both the necessity of protection from drought and from the
destructive force of the breakers. We are just beginning
to understand the significance of the shapes of shells con-
sidered from these points of view, and some of the more
obvious adaptations only can be pointed out here.
Most of the molluscs of the shore have either a shell
composed of two valves, like cockles, mussels, and their
allies, or have univalved shells like limpets, periwinkles,
and whelks (Gasteropods). Among the latter the limpet
represents the simplest though perhaps not the most primi-
tive condition. Its shell is simply conical, and protects the
dorsal region of the animal only ; but as everyone knows
the limpet has extraordinary clinging power. The thick
shell prevents loss of water by evaporation, the firm attach-
ment prevents dislodgment by the force of the waves. The
majority of the univalved Molluscs on the shore differ from
the limpet in possessing a spirally coiled shell, which is
often exceedingly thick and dense, and into which the
whole animal can be withdrawn. Such forms as periwinkles,
whelks, tops, dog-whelks and others do not cling like the
limpet, but when alarmed or attacked often drop suddenly
from their attachment. As they do so they withdraw com-
pletely into their shells, and close the opening behind them
by a shutter, or operculum, which exactly fits the orifice
(see Fig. 70, p. 244). This done, the animal is completely
encased and protected from extremes of temperature. The
shell is so dense that the breakers do relatively little harm,
even though the animals are rolled about roughly enough.
It is believed that the shape and the sculpture of the shell
THE GENERAL CHARACTERISTICS OP SHORE ANIMALS. 7
are all of importance in giving strength to the shell, and in
minimising the danger of rough usage. How successful as
a protection the shell must be is demonstrated not only by
the great abundance of periwinkles, whelks, etc., on the
rocks, but also by the way in which they expose themselves
to view when the tide ebbs, braving the dangers of frost
and sun.
The Bivalve shell seems on the whole less efficient as a
means of protection, at least very few Bivalves live on the
rocks in the exposed way in which the periwinkles and dog-
whelks do. Some, like the mussels, grow in great colonies
in sheltered places, very many live buried in sand, not a
few burrow in rocks, but most are very liable to wholesale
destruction in storms. As a rule the Bivalves have little
power of locomotion ; they often spin a mass of silky
threads, by means of which they anchor themselves to solid
bodies, and which, as in the mussels, may constitute their
chief defence against the force of the waves.
Analogous to the habit of shell-making is the process of
tube-building, which is carried on by hosts of worms. In
most cases the tube consists of an organic substance secreted
by the animal, to which are added foreign particles such as
grains of sand, or fragments of stone and shell. Among
the tube-building worms are the "sand-mason" (Terebella),
a very common form, Sabellaria, a social worm, which builds
sandy tubes, and many others. In many cases these tubes
must be looked on as chiefly a means of protection against
organic foes, but in other cases they are strong enough to
protect the animal from the. dangers of its physical environ-
ment.
By far the most effective method of protection against
these dangers is, however, the habit of burrowing. A
burrowing animal obtains protection from the waves, save
in great storms; it obtains permanent moisture, a more or
less even temperature, and finally is safe from the persecu-
tion of most organic foes. The list of benefits is so long
that it is no wonder that so many different kinds of animals
have acquired burrowing habits. We can mention only a
few of them. If you stoop under overhanging ledges of
rocks, or turn over weed-incrusted stones, you may often see
numerous holes in the rock, from each of which a red star
8 LIFE BY THE SEASHORE.
protrudes. Touch these stars, and they instantly disappear,
ejecting a feeble jet of water as they do so. If by means oi
hammer and chisel you investigate the rock, you will find
that the stars are the breathing-tubes or siphons of a little
bivalved Mollusc, called Saxicava, on account of its rock-
boring habits. The little creature remains permanently
within its rocky burrows. When the rock is covered by
water it protrudes its red tubes, and through them both
feeds and breathes ; when the tide ebbs, or enemies threaten,
it withdraws the tubes, and is safe. Another, and in some
ways an even more interesting rock-
boring Mollusc, is Pholas, of which one
species is common in the soft fissile rock
called shale by geologists. While walking
over stretches of shale you may often
notice that it is perforated by numerous
round holes. When the rock is covered
by water these holes are filled by a brown
fringe, with some superficial resemblance to
a sea-anemone. At a touch the fringes
vanish like a shot. The shale is very soft,
and can be readily pulled up in great
blocks, when you will find that the holes
are the openings of the burrows of Pholas,
FIG. \.-Phoias crispata, a .wllite Bivalve, with a shell which gapes
from under surface, to widely, and is beautifully toothed and
tSSv!SKSi£ sculptured. In the Firth of Forth, where
/, foot ; s, siphon. beds of shale are abundant, the rock is
often simply riddled by Pholas burrows. Other species of
the genus burrow in hard rocks, and are then much less
easy to extricate.
Far more numerous than the rock-borers are the burrowers
in sand, which if it does not form so secure a resting-place
as the solid rock is one more easily obtained, and is taken
advantage of by many animals. Objection may be taken to
the word "many," in view of the fact that children often dig
in the sand for hour after hour, and yet rarely come upon a
living creature. But the explanation is simple. Animals
which burrow in sand almost invariably live on sand ; they
can therefore only live in sand which is impregnated with
organic particles. Such sand occurs usually in the vicinity
THE GENERAL CHARACTERISTICS OF SHORE ANIMALS. 9
of rocks or near the mouths of rivers, while in the long
stretches of clean sand most frequented by children organic
particles are remarkable for their absence. To illustrate the
variety of sand-burrowing animals, I may give a list of the
spoil taken by a party of which I was a member at some
sands in the Firth of Clyde, near Millport. We got first
a burrowing sea-anemone (Pe&hia), any number of heart-
urchins (Echinocardium cordatum) covered with beautiful
golden spines, Synapta, a curious pink worm-like creature
really allied to sea-urchins, razor-shells (Solen), otter-shells
(Lutraria), old maid shells (Mya), all living and active, any
number of ringed worms of various kinds, some ribbon-
worms, and many sand-eels, and all these occurred together
within a very limited area, and were taken in the course of
an hour's digging.
FIG. 2. — Sand-launce or sand-eel (Ammodytes tdbianus). After Day.
One is tempted to say of each set of marine animals that
they are the most interesting of all, but surely there is a
special interest about sand-burro wers ! The worms, perhaps,
one might pass over, for the common earthworm has
familiarised us with the burrowing habit, but how does
a sea-urchin get deep down into the sand ? Those mentioned
above were found in one locality, living, not in sand, but
in a sandy gravel full of stones and shells. The shell or
test of the heart-urchin is as fragile as glass, so thin that
unless held with care one's fingers go through it. How does
it bore its way among sharp-edged stones without injury?
So with many of the others, as the spade turns them up
a dozen "hows" and "whys" crowd upon one. Digging
in the sand may seem a childish pastime enough, but if you
choose your sand aright it has many fascinations.
There are many other of the more sedentary shore
animals which do not burrow and are not protected by
a thick shell. These usually settle down in damp and dark
situations where the sun's rays do not penetrate, or they
10 LIFE BY THE SEASHORE.
creep under stones and into chinks and fissures of the rocks
as the tide ebbs, to seek protection both from sun and wind
and from the keen eyes of the birds. It is in search of
these that the shore-hunter diligently turns stones and
creeps under overhanging rocks, where the weeds drip and
the sea-squirts eject their tiny jets of water. Most of these
are protected from the force of the waves by the fact that
they are attached and sedentary, or by the shape of their
bodies which makes it easy for them to lurk in crevices out
of harm's way.
There are still other ways in which shore animals may
escape the dangers associated with the ebb and the flow of
the tide. Thus they may avoid these dangers by their own
activity, following the water as it ebbs seaward, and return-
ing with it when it once more flows landward. These are
best represented on the shore by some of the Crustacea —
such as prawns, some shrimps, various kinds of lobsters — •
and by certain fishes. In both cases, however, the power
of active swimming is comparatively rare in truly littoral
forms, probably because the strong shore currents make it a
danger rather than an advantage. Thus, of the shore fishes,
the blenny (Biennius pJiolis) remains lurking under stones
often quite uncovered by water, the sand-eels (Ammodytes
tobianus) often bury themselves in the sand, where stickle-
backs (G aster osteus) are also at times to be found. Among
the shore Crustacea, as we shall afterwards see, there is
evidence that in the higher forms the power of swimming
has been gradually lost, and the animals have been adapted
for life at the bottom and on the tidal rocks. This has been
accompanied in the crabs by a modification of the dorsal
shield or carapace, which has for its object the protection
of the gills from the risk of drying up. So carefully are
these protected in many crabs that the animals can live for
a long period out of water. In some cases, indeed, as in the
common shore crab, an exposure to air during a portion of
the day seems actually beneficial. While very many Crus-
tacea and a few fishes are thus rather to be reckoned among
the forms which lurk passively in hiding when the tide
ebbs, there are still a considerable number who are active
swimmers, and constitute the "floating population" of
the rocks. The capture of these can only be hoped for
THE GENERAL CHARACTERISTICS OF SHORE ANIMALS. 11
when they are trapped in some rock pool by the ebbing
waters.
The above brief account of the way in which animals
protect themselves against the dangers of their physical
environment may serve as an outline which your experience
in actual collecting will later enable you to fill up. We
may now look for a little at the ways in which the shore
animals protect themselves from their organic foes. In
some cases, as we have already seen, the same artifice which
protects an animal from the one set of dangers protects it
from the other. The fisherman's lob-worm (see Fig. 10,
p. 30) is greatly relished by very many fish ; we can hardly
doubt, therefore, that it is, in an ordinary way, protected
against these by its burrowing habit. Most tube-worms
vanish into their tubes instantly at the least alarm, often
merely at a shadow. It is reasonable to conclude that the
tube affords a natural protection. It is not very uncommon
on the shore to find mutilated whelks, which have apparently
had their anterior region bitten off by fish before they had
time to withdraw into the shell ; a fact which again suggests
the protective value of the shell. Facts of this kind might
be multiplied indefinitely, but the protective value of hard
shells is in the general case sufficiently obvious, and we may
pass on to less familiar means of defence.
Many shore animals seem to be protected by their
weapons, whether of offence or defence, or by some un-
pleasant attribute. Thus the great pincers of crabs and
lobsters make them dangerous adversaries ; jelly-fish and
sea-anemones are protected by their stinging-cells; sponges
are often full of sharp spicules ; many worms have an
elaborate armature of bristles; and so on. The power of
self-mutilation, or autotomy, is also widely spread among
shore animals, and must often assist their escape. Most of
the shore crabs, if seized by a limb, will throw off the limb
and escape. Brittle-stars break their rays at the slightest
touch, and the separated portion keeps up active movements
for some time. Not a few "worms" throw off gills or
tentacles or other portions of the body when molested. In
this case the separated organs move about even more actively
than when attached, and doubtless distract the attention of
the enemy. In all cases where autotomy is practised, the
12
LIFE BY THE SEASHORE.
animals possess the power of renewing the parts thrown off.
Almost as curious as self -mutilation is the habit of
"shamming dead," which is practised on the shore by
many Crustacea, just as it is on land by many insects.
Sand-hoppers and the common shore crab may be mentioned
as artists in this subterfuge. The habit doubtless saves
them from the attacks of animals which confine their
attention to moving prey.
Again, not a few animals seek safety in the companionship
of other stronger and better protected animals. Examples of
this are abundant on the shore. Thus the common hermit-
crab often shelters a worm (Nereis fucata) within its shell,
which no doubt finds the hermit's claws and borrowed house
a protection against some foes. The hermit-crab of the
West carries about with it an anemone (Adamsia) which
throws out a quantity of stinging threads, and thus perhaps
protects the hermit from attack, while the common hermit-
crab often has its shell covered by a luxuriant growth of
possibly defensive zoophytes.
FIG. 3.— Hermit-crab with the shell covered by a zoophyte colony
(Hydractinia echinata). After All man.
A pretty little Bivalve (Modiola) lives habitually within
the tough tunic of sea-squirts, while a still more enterprising
little Crustacean actually lives inside the body of the sea-
squirt. Within the shells of the horse-mussel and some
other Bivalves, there may be often found a little soft-shelled
crab, which finds there the protection its soft coat cannot
THE GENERAL CHARACTERISTICS OF SHORE ANIMALS. 13
give. These are only a few examples of partnership or
symbiosis, which is a common phenomenon among shore
animals. It is very apt to degenerate into parasitism, where
the one partner not only gets house room, but actually lives
upon the host.
We have seen that the shell of shellfish affords an
apparently efficient protection against many dangers, but it
is important to note that not a few Univalves have entirely
lost their shells. These constitute the forms known as sea-
slugs, sea-lemons, and more generally as Nudibranchs, or
" naked-gilled " forms. Many of these occur on the shore,
and though on account of the absence of any means of
protection against drought they are confined to the zone
near low-tide mark, yet there they are abundant enough.
Many of them are very brightly coloured, and most are
furnished with little processes, either simple or branched,
which decorate the back, and add greatly to the beauty.
FIG. <i.—Doto coronata, a sea-slug with the back ornamented with curious
branched processes. After Alder and Hancock.
In spite, however, of the frequent conspicuousness of the
animals, and the absence of any protective shell, there can
be no doubt that they are very rarely attacked or eaten by
the other shore animals. Many naturalists believe that the
bright colours and conspicuous processes are an advertisement
of inedibility, like the vivid colouring of some inedible
caterpillars. It is interesting to note, on the other hand,
that while many Nudibranchs are conspicuous and highly
coloured, others are exceedingly like, the weeds and corallines
among which they live. Thus Doto coronata (Fig. 4), a
beautiful and not uncommon sea-slug, is very like the
common coralline, or pink limy weed, and is exceedingly
14 LIFE BY THE SEASHORE.
difficult to distinguish from the coralline. There seems no
reason to helieve that such "protectively" coloured forms
are edible any more than the conspicuous forms, and they
do not attack active prey ; so that the use of the particular
coloration does not seem very clear. It is, however, certain
that a close resemblance between organism and surroundings
is a very common characteristic of shore animals, and doubtless
often conceals them from their enemies, and enables them
to steal unperceived upon their prey. In not a few cases
the coloration is variable, changing with the surroundings.
As groups in which this phenomenon may be looked for we
may mention Crustacea, such as crabs, shrimps, and their
allies; fishes, such as flounders, plaice, etc.; and even anemones,
such as the "cave-dweller" (see Fig. 25), Sagartia troglodytes,
whose colour varieties seem to show a relation to its sur-
roundings.
In connection with this same subject we may notice the
habit of " masking " themselves which is displayed by many
Crustacea. Practically all the different kinds of spider-
crabs are found to have the back and legs covered by a
more or less thick coat of weed or zoophytes. These are
actually attached by the crabs themselves, as may be readily
seen in captivity, and are fastened on by very curious
hooked hairs with which the bodies of the crabs are covered.
The common Hyas araneus (see Fig. 55) of the East Coast
may be specially mentioned as a spider-crab which goes
about elaborately masked. Another form, Inachus dorset-
tensis, which lives in deeper water, shows a decided
preference for sponges, and is often found with back and
legs covered by masses of it. Curiously enough, the sponge
itself often has its interstices filled with the muddy burrows
of a little Crustacean (one of the Amphipods), which is at
times present in great numbers.
These cases of "masking" pass by insensible gradations
into true symbiosis, where there is a constant association
between two animals, as in the cases noted above.
There is one danger to which shore animals are subjected
which we have not as yet noticed, because although
doubtless they have acquired means of protection against
it, yet the adaptation is physiological, that is, a matter of
function, and cannot be studied as readily as a morpho-
THE GENERAL CHARACTERISTICS OF SHORE ANIMALS. 15
logical or structural characteristic can be. This is the
danger associated with a possible influx of fresh water into
the shore area. In most cases where the shore is fringed
by a long stretch of rocks, these rocks are interpenetrated
by fresh-water streams, and the animals in the neighbour-
hood of these streams are liable to be overwhelmed by
floods. On a larger scale, rocks in the vicinity of rivers
are similarly liable to the influx of large bodies of fresh
water. As is well known, many fish are not only indifferent
to the contact of fresh water, but at the breeding season
actually court it. Among those which can alternate from
fresh to salt water without danger are the salmon, eels,
sticklebacks, and others. Not a few fish, again, are ex-
tremely sensitive to the action of fresh water, which seems
to produce an almost instantaneous paralysis. Among the
lower animals a good many of the Crustacea and some
shellfish or Molluscs haunt estuaries or the neighbourhood
of streams, and are indifferent to the presence of a consider-
able amount of fresh water. In the vast majority of cases,
however, especially in the case of animals without shells,
fresh water acts as a powerful poison. This is especially
interesting, because we know that the salinity of sea water
varies greatly ; thus the Mediterranean is very dense, while
the Baltic contains a very much smaller portion of dissolved
salts, and yet some animals inhabit both areas. Experiment
shows that while an animal will not support direct trans-
ference from one of these media to the other, it can be
gradually educated to do this, if the changes are made
sufficiently slowly. Part of the interest of the shore area
is that it affords constantly varying conditions of life, the
variations under ordinary circumstances being small enough
to allow the animals time to adapt themselves to the new
conditions. It is because of these constant variations that
evolution has proceeded so rapidly in the area.
One other general point must be considered, and that is
the way in which the animals of the shore area are dis-
tributed. In the preceding pages some attempt has been
made to indicate the vicissitudes of shore life, and to suggest
the great variety of conditions which may prevail there.
One consequence of this is that particular shore animals are
often very local in their distribution. Obviously an animal
16
LIFE BY THE SEASHORE.
which is adapted for life in mud must be confined to areas
where mud-beds occur, and thus be absent from long
stretches of shore. But apart from simple cases of this
kind, it often happens that an animal whose adaptation
to some special condition of life is not very obvious, is yet
confined to certain localities, and is absent from intervening
places which are apparently equally suitable. Thus the
beautiful Alcyonium (Dead Men's Fingers) only occurs
sporadically between tide marks, probably in part because
it offers little resistance
to wave action, and re-
quires peculiarly shel-
tered spots for fixation.
Again, the Plumose
anemone (Actinolola
dianthus, Fig. 26, p. 73),
one of the finest of our
British anemones, is on
the East Coast at least
a very local form, some-
times occurring in great
beauty and profusion in
one particular spot only
in a large bay. Many
other examples might
be given, but without
labouring the point, we
may say generally that
although it is an advan-
tage for .adult shore
animals to be firmly
fixed, or to be able to offer passive resistance of some sort
to wave action, yet it is also highly desirable that they
should at some period of life possess sufficient power of
movement to enable the species to be carried to fresh
localities, and suitable localities may be a considerable
distance away from the home of the parents. In point
of fact, almost all shore animals produce minute active
young, which usually live near the surface, and are eminently
well adapted for transport by currents or by their own
activity. One of the most interesting subjects of study
Fio. 5.— Dead Men's Fingers (Alcyonium digi-
tatum), a colony of small polypes.
THE GENERAL CHARACTERISTICS OF SHORE ANIMALS. 17
on the shore is the life-history of the common animals,
and the peculiarities of the young forms. In some cases,
as in the sea-firs or zoophytes, there is what is known as
alternation of generations, that is the occurrence in one
life -history of two or
more different forms,
differently produced.
Thus, the sessile sea-fir
buds off a little swim-
ming-bell or tiny jelly-
fish, which produces
the eggs from which
new sea-firs arise. As
the swimming-bells can
move actively through
the water, and are also
very readily swept along
by currents, it must
often happen that the
eggs are deposited some
distance away from the
original sea-fir colony.
Most worms produce
eggs which give rise to
minute top-shaped Iarva3,
which live near the sur-
face of the water and
ensure the distribution
of the species. Even
the sluggish Echino-
derms, the starfish, sea-
urchins, and brittle-stars,
produce minute active
larvae, which present
no apparent resemblance
to the adult, and are
adapted for quite a
different kind of life.
But it is among the Crustacea that we have the most
complex and interesting life-histories. In them there is
not merely one peculiar larval form, but the young undergo
Fio. 6.— Swimming-bell (Sarsia) of a sea-fir,
showing the long tongue, or manubrium,
swollen by the contained eggs, and the
four long tentacles which bear stinging-
cells. After Allman.
18 LIFE BY THE SEASHORE.
a succession of remarkable changes before they attain the
adult form. Our present interest in these cases is due to
the fact that the peculiarities of the larvae ensure the dis-
tribution of the species, and compensate for the limitations
of that sedentary life which the exigencies of shore life
force upon so many of the adults. But we shall see later
that these Iarva3 are also of great interest in possibly
throwing light upon the origin of the animals of the sea-
shore, and upon their relations to the animals of the other
parts of the ocean.
CHAPTEE II.
THE STUDY OF SHORE ANIMALS.
Where to begin — How to begin — The study of common animals —
Characters of limpets— Their structure and habits — The common
crabs and their characters — Classification of shore animals —
General hints as to methods.
WE have in the preceding chapter considered in outline
the special nature of the surroundings among which
shore animals pass their lives, and the nature of the adapta-
tions by which they respond to the peculiarities of these
surroundings. In this chapter we have to consider how the
would-be naturalist is to become acquainted with the teem-
ing life of the seashore. The first question to be asked is,
Where shall we begin1? It is obvious from the foregoing
that except where the luxury of a dredge is available the
field of action must be the tidal rocks. It is true that the
mud-flats at the mouths of rivers and streams may furnish
many different worms, some burrowing sea-urchins and sea-
anemones, cockles, mussels, and razor-shells; and the streams
themselves may abound with shrimps, sand-hoppers, sand-
eels, shore crabs, and other hardy creatures; yet, alike for
accessibility and for wealth of types, the rock pools claim
pre-eminence, and it is with them that it is advisable to
begin.
It is probable that the question, Which rocks 1 will often
be determined by other causes than the naturalist's predi-
lections, but it is nevertheless worth while to point out what
conditions are especially favourable. For my own part I
should be inclined to regard as the most important requisite
that of ready accessibility. Where pools of considerable
depth are within easy reach of the shore, the observer may
19
20 LIFE BY THE SEASHORE.
hope for a tolerable harvest of some kind. There is un-
doubtedly great variation in the number, both of indi-
viduals and species, obtainable even in places not far distant
from one another, and this is especially true in regard to the
wreckage flung upon the shore. It not infrequently happens
that the set of the current brings treasures to one perhaps
small area of a bay, which may elsewhere yield little or
nothing even to careful and long- continued search. To
those beginning the subject, however, these waifs and strays
must rank second to living forms whose habits may be
watched from day to day, and for these we must seek the
rocks. A famous horticulturist once said that the best
advice he could give the amateur was to like what he could
grow, if he couldn't grow what he liked. Similarly, the
shore naturalist may be advised to interest himself in the
animals he finds, if he cannot find those in which he is
interested. There are few rocks so barren as to yield
nothing to the industrious hunter, and in the general case
the statement that a particular area is unproductive, and
its pools void of life, is more likely to be based upon in-
efficient observation than upon fact. Hopefulness is indeed
justified even where the surroundings seem adverse in the
extreme. I have found brilliantly coloured specimens of
the sea-anemone, Anthea cereus, in company with many
Nudibranchs and rare Annelids, on rocks which I was
assured on good authority were hopelessly poisoned by
drainage from lead mines. In the Firth of Forth colonies
of Alcyoniam in perfect health and beauty may be found
within a few yards of a shore piled with the accumulated
nastiness of our civilisation, and similar examples might be
multiplied indefinitely. Nevertheless, as a slight guide to
those whose choice of a summer resort is unhampered, a
brief list of places famous for their shore animals is given
at the end of the chapter.
While, however, we recognise in this way that there are
few patches of rocks which are not worth a hunt, it is well
also to consider under what conditions there is likely to be
"good hunting." In the first place it is important to realise,
what we have already dwelt upon, that few marine animals
like the full glare of the sun, and fewer still the danger of
drought. Now the tide ebbs and flows twice a day, and
THE STUDY OF SHORE ANIMALS. 21
with a spring tide the water may drop a vertical height of
up to forty feet; so that it is obvious that unless the moisture-
loving animals can allow for the periodic movement of the
waters, they must be very liable to elimination either by
direct drying up, or by exposure to the keen sight of the
birds who follow the receding waves. So far as we know,
the tide has always ebbed and flowed, wherefore the shore
animals have had time to learn their lesson. The result
is that sedentary animals — like sea-anemones, sea-squirts,
Alcyonarians, sea-firs, and the like — establish themselves
only under overhanging rocks or in deep crevices where,
even when the waters retreat, there is a grateful coolness
and moisture, and a refuge from keen eyes. Sluggish forms,
like many Annelids, the ribbon- worms, the starfishes and
brittle-stars, sea-slugs, and many more — which are equally
unable to follow the water, and equally unwilling to be
deprived of moisture — creep into similar situations or under
stones and weed, to pass their time of waiting; and there
are left exposed a few hardy forms only, with some special
means of minimising the risk of drying up. Finally, at every
tide, but more especially at the springs, certain active forms
are prevented by untoward circumstances from escaping with
the ebbing water, and are held prisoners until it comes again.
FIG. 7. — Lump-sucker (Cycloptenis lumpus). After Day.
Among such are many fish, lump- suckers, gobies, stickle-
backs, sea-scorpions, and others; at certain seasons of the
year the large cuttles, various Crustacea, and many other
curious creatures. If these facts are borne in mind, it will
be obvious that rocks are most likely to yield a rich harvest
22 LIFE BY THE SEASHORE.
when they are deeply fissured and hollowed out, leaving
many shady corners and deep pools ; for in the former the
sedentary forms will be found, while the latter act as traps
to the floating population. It is not, however, sufficient that
pools and fissures should exist : there must also be ready
access to them. In the case of stratified rocks readiness of
access depends largely upon what geologists call the dip.
The ideal case is, perhaps, that where the rocks run out to
sea in long ridges of which each stratum overhangs its
neighbour, while between successive ridges are long channels
whose contents are available until the tide actually covers
the ridge. When, on the other hand, the rocks dip outwards
to the sea, these same channels form dangerous pitfalls to
the too enthusiastic naturalist, who lingers on the distant
ridges regardless of the eddying currents which are cutting
off his retreat. This danger is sufficiently real to make it
decidedly worth while to take a general survey of the rocks,
and study their peculiarities before beginning serious work.
This done, there still remains one more point to settle,
and that is the part of the rocks to which our energies are
to be devoted. Broadly speaking, there are two possibilities
— the strictly littoral rocks, those which are exposed at
ordinary low tide, and are only completely covered for a
relatively brief period about the time of high tide ; and the
Laminarian zone, which is only accessible for a short time at
extreme low water during spring tides, and then only in
part. It is in the pools sheltered beneath the long fronds of
Laminaria, or oar-weed, that the greatest treasures are to
be found — the tiny Eolis coronata, with its brilliant colour-
ing in blue and crimson; the active Galatheas, darting back-
wards through the pools; the larger Annelids, with their
bright pigments and gleaming iridescence, and many others
— but the time during which these pools are accessible is
woefully brief, and the beginner is recommended to confine
himself, at least at first, to the rocks nearer the shore.
Let us suppose ourselves, then, ready to start for an
introductory expedition to the rocks. First, as to the
equipment, let this be as simple as possible ; the danger lies
not in collecting too little, but in the general case in
attempting too much. According to my experience the
average beginner provides himself with numerous buckets
THE STUDY OP SHORE ANIMALS. 23
or bottles, and arriving at the rocks proceeds to transfer into
these all the animals and pretty pieces of weed which catch
his eye. On returning home the spoil is placed in some
corner until the weary traveller is rested, is then forgotten,
and remains neglected until it ceases to be an object of
delight, and is finally thrown out by the irate housemaid,
the net result to all concerned being usually an impression
that the study of marine zoology is associated with odours
of a powerful and unpleasing nature. It is impossible to
speak too strongly of that collecting instinct which leads
people to gather together all that they see, regardless of the
fact that they are leaving the world poorer for their neigh-
bours. Wherefore I would beseech the would-be naturalist
to think always of him that follows after.
If the mere accumulation of specimens be discouraged,
the question of how to begin remains unsettled; the oft-
repeated advice to study the habits of animals, like many
similar pieces of advice, not being of great practical value.
The way which is likely to lead in the long run to the best
results is probably to attempt first to acquire some know-
ledge of the commonest forms, and then later to utilise the
powers of observation which have been trained in this way
in a search for rarities. A detailed study of internal anatomy
is in most cases very difficult for those without previous
training, but a knowledge of external form is not to be
despised, and is readily acquired.
For example, any rocks will probably exhibit even to the
most casual observer such animals as limpets, crabs, and
various kinds of shrimps. Take the limpets first. The
most abundant form will be the common limpet (Patella
vulgata), but in Scotland or the North of England the tor-
toise-shell limpet (Acmcea testudinalis) is almost as common.
Far out on the rocks the transparent limpet (Helcion
pelluddum) will be found creeping over the great fronds
of oar-weed, and so on; the list might be extended to
considerable length, according to the locality. Now there
can be no better exercise, or more fitting introduction to
zoological study, than to choose two or more of these forms,
and study them until they can be recognised at a glance.
This may seem an easy task, but experience shows that it
is not so. At one time, when making some observations
24 LIFE BY THE SEASHORE.
on the tortoise-shell limpet, I attempted on several occasions
to get assistance in collecting specimens. The result was,
however, invariably that I was presented with young speci-
mens of the common limpet, with the assurance that these
were exactly the right thing.
The differences are nevertheless well marked. In the
common limpet the thick shell is marked with ridges
which project at the margin of the shell; in the other the
surface of the shell is perfectly smooth, and marked with
a beautiful "tortoise-shell" pattern in brown. In the
common limpet the inside of the shell is glassy smooth
and transparent; in the tortoise-shell it is opaque white,
except for an elongated brown mark in the upper part.
Between the animals themselves the differences are much
more marked, as will be readily seen by putting both into
a glass bottle and allowing them to crawl up the side. In
the flattened creeping sole or foot, in the pendent fringe
or mantle-skirt surrounding this foot, in the horns or ten-
tacles at the sides of the prominent mouth, there is marked
resemblance; but in Patella the side of the mantle next
the foot is pleated and vascular, forming the breathing
organ of the animal, while as the little Acmcea moves you
will see it protrude in front a single plume-like gill. As it
creeps up the glass, also, you will notice that its mantle is of
a delicate green colour, while that of the common limpet is
dull-coloured ; the whole animal has also a delicate trans-
lucency beside which the common limpet seems coarse and
ungainly.
In habitat there is also a marked difference. At low tide
the common limpet is found far above the water level, with
its shell embedded in a slight excavation of the rock into
which it closely fits; the tortoise-shell, on the other hand,
is rarely found except in pools. The little pits which the
common limpet makes and inhabits, together with its tre-
mendous power of adhesion, must diminish the evaporation
of moisture, and therefore diminish the risk of drying up ;
the thick shell probably also aids in the retention of the
necessary water. If you knock a living limpet off the rock
you will find that the under surface is abundantly moist,
while the specimens which have been knocked off by the
birds and left foot upwards seem to dry directly. The
THE STUDY OF SHORE ANIMALS. 25
tortoise-shell limpet does not fit nearly so closely to the
rock, its shell is much thinner, and its tissues more delicate ;
it is probably for these reasons that it never leaves the
pools. It must, of course, be realised that both are true
aquatic animals, and that a certain amount of moisture is
an essential of existence to both. The difference between
the power of adhesion of the two forms is so marked that
it can be employed as a means of distinguishing them where,
from depth of water or other cause, the characters of the
shell cannot be clearly seen. As everyone knows, the com-
mon limpet may be dislodged by a sudden and unexpected
blow ; but if the first attempt fail, the alarmed animal
adheres so tightly that a knife is necessary to detach it.
The tortoise-shell limpet, on the other hand, can always be
removed with the fingers alone. It never reaches the size
which the common limpet does, but in specimens of the
two forms of the same size the difference in the clinging
power is quite distinct.
This description should be sufficient to permit of an easy
recognition of the two forms, and they should be studied
until eye, touch, and muscular sense are so trained that there
is no possibility of error. This may seem a trivial occupa-
tion, but some preliminary training of this kind is essential
to anyone desirous of acquiring an acquaintanceship with
species; and the identifying of species, though now sadly
out of fashion, is an occupation which may yield one of the
subtlest of pleasures. Of late years so much has been said
of variation and its consequences, that not only the general
public, but even some zoological students, seem to have an
idea that species were something abolished by Darwin, and
that the notion that there is constancy and orderliness in
nature is a mediaeval myth. It may well be that the older
naturalists made too much of that constancy, and toiled
over their species-mongering until they reduced the organic
world to the condition of a labelled liortus siccus instead of
a living, growing reality ; but it does not appear that our
gain is great if we swing to the opposite extreme, and
inculcate the idea that there is no constancy or definiteness
in nature at all. So much of the present-day academical
teaching seems to have this result, that I cannot but urge
anyone beginning open-air studies to find some time for
26
LIFE BY THE SEASHORE.
species work, and for this habits of patient and minute
observation are essential. It is necessary, also, to emphasise
the necessity for handling specimens freely. The healthy
child instinct to touch everything seen is so thoroughly
educated out of most people, that they never seem to realise
how enormously sense impressions are strengthened when
hand and eye work in combination. In studying zoology,
therefore, from the first train your fingers.
The preliminary study recommended in the case of
limpets may be equally well carried out with the different
kinds of crabs. The hard coat of the crabs, which gives
perfect consistency to the form, renders them particularly
well fitted for the present purpose. On every shore two
kinds of crabs are almost certain to be found : these are
the common shore crab
(Cardnus mamas, see
Fig. 49, p. 153), and the
edible crab (Cancer
pagurus}. The former
on the tidal rocks will
be found most in evi-
dence, but small forms
of the latter are usually
very abundant, especi-
ally far out, and those
who know where to
look will not fail to
find examples of quite
considerable size. The
young of the shore crab are extraordinarily variable in colour
— they change, indeed, according to their surroundings —
while the colours of the young edible crabs are much more
constant, though often quite unlike those of the adult. It
is not necessary to discuss in detail the differences between
the two forms ; there are probably few people who could not
recognise an adult edible crab when they see it. Unless,
however, your perception of form is much stronger than
your perception of colour, you will probably find that the
colour variations of the young confuse your judgment, and
that you have some difficulty in settling the nature of a
handful of small crabs gathered at random. If this is so,
FIG. 8.— Edible crab (Cancer pagurus).
THE STUDY OF SHORE ANIMALS. 27
the best plan is to take fair-sized specimens of the two
forms and compare them point by point. You will notice
at once that, just as in the case of the limpets, there is
much general resemblance. In all the essentials of structure
the two are similar, but there is nevertheless a well-marked
difference. Study the two until you can say precisely
wherein the difference lies (the shape of the dorsal shield,
or carapace, and of the numerous legs will be found
especially important), and then return to the young speci-
mens. If your analysis has been careful you will find that
the difficulty has vanished, and that you can now sort your
specimens without fear of error.
There are many other common animals which can be
similarly employed as a means of strengthening the percep-
tion of form in animals, and such introductory training will
be found of much value afterwards. It will also serve to
familiarise you with the haunts and habits of the common
types, a point of much importance. As, however, your
acquaintance with the rocks and their inhabitants increases,
you will find the need of a classification of animals — a
method of pigeon-holing your too numerous facts. We shall
therefore consider next an outline classification.
The first point to notice is that the fauna of the rocks is
so abundant and so varied that, among Invertebrate or back-
boneless animals at least, there are few great groups which
are not numerously represented. The sea, the fruitful
mother of all things, retains representatives of most of her
children within herself. In spite, therefore, of the fact that
our classification is professedly based on marine forms only,
we shall find few important blanks in it.
Lowest of all, and including forms with which we shall
not concern ourselves much here, are the PROTOZOA, the
primitive unicellular organisms, resembling those from which
all others have originated. Consisting as they do of single
cells, or of colonies of cells in which the units are not
dependent upon one another, it will be readily understood
that the Protozoa are mostly minute, often excessively so.
Many forms, however, make shells of lime or flint, and may
by their abundance give rise to considerable deposits. Such
Protozoa helped to form the chalk of the South of England,
and are forming the oozes (Globig&rina ooze and Radiolarian
28 LIFE BY THE SEASHORE.
ooze) which are at present accumulating on the floor of the
ocean. Protozoon shells may be found among shell-sand on
the rocks, but the Protozoon which is most likely to be
encountered without special search is the little Noctiluca,
the chief cause of the occasional li phosphorescence " of our
seas. It is just visible to the naked eye, and in the dark
appears like a tiny point of light. Into the characters of
the Protozoa we shall, however, not here enter in detail.
The next great class of animals includes much more con-
spicuous forms — the SPONGES, long thought to be plants.
The familiar bath sponge is, of course, merely the skeleton of
a once living animal, or rather of a collection of individuals,
a colony of sponges. For an example of a simple sponge
you should look under overhanging ledges of rock, and you
will find a little sac of dull colour and compressed form
hanging downwards. One end is fixed to the rock, the other
terminates in an opening which is not a mouth, for nothing
enters by it, but which serves as a means of exit for the
currents of water which enter the central cavity by numerous
pores in its walls. This central cavity is simple and un-
. divided ; there is no alimentary canal, and no organs, the
sponge is merely a thin-walled sac, lined with cells bearing
motile threads or cilia, which by their movement produce
continuous currents. Without power of locomotion, with but
little feeling, and no active means of defence, the sponges
would not be able to survive as they do were it not that they
are passively protected by their power of forming a skeleton.
This skeleton may be composed of sharp spicules of lime or
flint, or of silky fibres, as in the bath sponge, but in all
cases it seems to render the sponges ugly mouthfuls, and so
induces most animals to let them severely alone. In addition,
many sponges have a strong odour. Many are brightly
coloured.
The little purse-sponge (Grantid), described above, has
usually a single large opening, .through which water leaves
the central cavity ; but many sponges, like the bath sponge,
or the very common crumb-of -bread sponge found on the
shore, have many of these large openings ; in the crumb-of-
bread sponge they stand up on the flat surface like little
craters. As each opening represents an individual, such
sponges are really colonies, formed by budding from an
THE STUDY OP SHORE ANIMALS. 29
originally simple individual. Very many sponges are in
this way colonial.
Above Sponges, but still forms of very simple structure,
are the CCELENTERA, or hollow-bodied animals — sea-anemones,
corals, sea-firs, "dead men's fingers," jelly-fish, and many
others, almost all beautiful in form and colour, and with a
delicacy and fragility which makes it essential that they
should be studied in the living condition. They agree with
Sponges and differ from higher animals in
containing one central cavity only, instead
of having an alimentary canal inclosed
within a general body-cavity. They have,
however, a true mouth surrounded by
tentacles, instead of the numerous pores
of the Sponges; the skin, especially on
the tentacles, contains offensive and de-
fensive stinging-cells which can be ejected;
there is often a skeleton of lime or some
other substance; their symmetry is radiate,
like that of a flower. Many of the Cos- FIG 9.—
lentera are colonial, and it is such colonial Hi*^d"k' Ooeofttie
forms which build up the coral reefs of sea-ihs.
warm seas.
Above the Coelentera we come to the UNSEGMENTED
WORMS, animals not nearly related to one another, but all
differing from the Coelentera in having distinct anterior and
posterior regions — a distinction of head and tail, in having
a separate alimentary canal within the general body-cavity,
which may, however, be largely filled up, and in the greater
complexity of their structure. Among these we shall be
concerned only with certain little flat-worms called Turbel-
laria, and with the ribbon-worms (Nemertea).
Much more highly differentiated, but sometimes loosely
included under the heading of " worms," we have the
SEGMENTED WORMS, or ANNELIDS. In them the body is
divided into successive rings, or segments, of similar struc-
ture, which usually bear locomotor organs furnished with
bristles. There is a well-developed body-cavity, which
opens to the exterior by little coiled tubes, or nephridia,
structures of much importance to the morphologist. The
Annelids which are especially adapted for a marine life
30
LIFE BY THE SEASHORE.
(Polychseta), are very numerous, and include many interest-
ing and beautiful forms. To them we shall return at
length. They are recognised by the
elongated segmented body, and the
'p lateral tufts of bristles.
The next group, somewhat iso-
lated in position, and not closely
related to the foregoing, is that of
the ECHINODERMS, or Prickly Skins,
including sea-urchins, starfishes,
brittle -stars, sea -lilies, and sea-
cucumbers; marine forms with limy
skeleton and radiate symmetry, al-
most always easy to recognise and
classify. They have a peculiar
" water vascular" system, which
in the common starfish, for example,
is connected with the delicate trans-
_g parent tube-feet, by means of which
the animal moves.
The next great class is that of
the ARTHROPODS, or animals whose
bodies are made up of a series of
rings or segments, which are fur-
nished with hollow jointed feet. The
vast majority of the shore Arthro-
pods are CRUSTACEA, which take on
the shore rocks the place taken by
the Insects on land. The Crustacea
include crabs, lobsters, shrimps, sand-
hoppers, etc., animals with two pairs
of feelers on the head instead of one
FIG. 10 —Fisherman's lob-worm pair as in Insects, with a har.l, limy
Muft of bristles ;*; pa^aliV coat , and breathing by gills instead
everted proboscis. A common of the air-tubes of Insects. Ihero
are an enormous number of Crusta-
cea on the shore, where they occupy all zones from high-
tide mark to deep water. They are the great scavengers of
the sea, for many of them live on dead and putrefying
matter. In this respect also they resemble Insects, which
are the great carrion feeders of the land.
THE STUDY OF SHORE ANIMALS.
31
The last group of Invertebrate animals, or those without
a backbone, is the MOLLUSOA, including Bivalves, like mussels,
scallops, cockles, etc. ;
Gasteropods, like peri-
winkle and whelk; cut-
tles, like squid and
octopus. The Mollusca
have soft, unsegmented
bodies usually covered
by a shell secreted by
a fold of skin called
the mantle, but many
shore Molluscs have no
shell. They usually
breathe by gills Or by FIG. ll.-Common scallo
the mantle, and have A bivalve Mollusc.
a very characteristic
muscular protrusion called the foot, which is usually the
organ of locomotion, and is well seen in the garden snail,
where it forms the creeping surface.
The Vertebrates of the shore include the FISHES, easily
recognised without special description, and the TUNICATES, or
sea squirts, a strange set of animals much modified and not
easy to recognise. Those on the shore are of two kinds —
the simple forms which are little shapeless sacs found under
stones and overhanging rocks, and the compound forms
which consist of little stars within a sheet of jelly-like
substance which spreads over rocks and stones. The simple
forms have two openings at the upper end, from which on
an alarm they eject jets of water. They are enveloped in a
usually tough tunic, which can be torn off, and reveals the
soft body beneath. Of the details of structure something
will be said later.
The outline classification of shore animals just given may
be summed up in the following table : —
Invertebrata.
Animals which at DO time of life have a backbone or any
similar structure down the back. Gill-slits, or openings
between the mouth-cavity and the exterior, present in fishes
32 LIFE BY THE SEASHORE.
and sea-squirts, are here absent ; gills when present are out-
growths of the skin.
I. PROTOZOA — Minute, usually microscopic forms, im-
portant as furnishing food for higher forms.
II. SPONGES. — May be recognised by their spongy,
porous bodies, furnished with one or more open-
ings, and containing a skeleton of lime, flint, or
horn. The crumb-of -bread sponge and the purse-
sponge are common both in the fresh and dried
state.
III. CCELENTERA. — Hollow-bodied animals, including sea-
anemones, jelly-fish, sea-firs, " dead men's fingers,"
and many others. The mouth surrounded by
tentacles bearing stinging-cells is a very character-
istic structure.
IV. UNSEGMENTED WORMS. — The ribbon-worms have lank
unsegmented bodies, very uniform throughout
their length, and eject a thread or proboscis
when alarmed. The Turbellaria are flat and leaf-
like, and move with a peculiar gliding motion.
V. ANNELIDS, or SEGMENTED WORMS. — The body is
divided into rings, or segments, which bear
lateral tufts of bristles. Very many live in
tubes, and then the bristles may be inconspicuous.
VI. ECHINODERMS.— Prickly-sldnned animals, usually with
much lime in the skin; the body is more or less
star-like, and the delicate, transparent tube-feet
are very characteristic. Starfishes, brittle-stars,
and sea-urchins are the commonest kinds.
VII. ARTHROPODS. — These, the animals with jointed legs,
are represented by the hard -coated Crustacea —
shrimps, prawns, lobsters, crabs, sand-hoppers, etc.
— which are very varied in form, but are recognised
by the segmented body, the jointed legs, the hard
coat, the two pairs of feelers.
VIII. MOLLUSCA. — The Bivalves, such as mussels and
oysters and so on, are readily recognised by tho
THE STUDY OF SHORE ANIMALS. 33
double shell. The snail-like forms (Gasteropods)
have sometimes a coiled shell, sometimes a conical
one (limpet), and are sometimes without a shell.
They can be generally recognised by the creeping
foot and the horns on the head. The cuttles
have many arms bearing suckers. All Molluscs
have soft unsegmented bodies without appendages.
Vertebrata are represented on the rocks by Tunicates or
sea-squirts with their tough tunics, and by the Fishes, which
can be recognised without difficulty.
This account should enable even the beginner to fix
roughly the position of the common animals of the shore,
and is best learnt by repeatedly collecting all the animals
found within a given area, say a large pool, and sorting them
into their different categories. Such an operation can be
readily performed on the shore, and will add greatly to the
interest of the early visits to the rocks. It is easy to choose
or make a series of little pools which may represent the
different classes, then search the rocks in their neighbour-
hood, returning after each excursion to the pools to place
the spoils in their correct position. At first it is well to
have an additional reservoir for. what the naturalist calls
incertce sedis. It is not the least of the pleasures of field
zoology to find how quickly the eye becomes trained, how
the contents of the " uncertainty pool " steadily diminish as
the perception of form increases, and the eye picks out
perhaps the one obvious point which settles the position of
the animal. Errors are of small moment, for after all there
is error in the best and most recent classifications. Few
years pass in which it is not shown to the scientific world
that some form or other, not always an insignificant one,
has been assigned to a wrong position, and the best arrange-
ment is nothing more than an approximation. The point is
to draw up a classification which will as far as may be
express your knowledge. If it differs from that adopted by
other people, this may be due to your ignorance or to theirs
— if you but go on you will soon find out which ; it is
better to make an error and learn that you are wrong than
to accept as dogma a classification which means nothing to
you.
34 LIFE BY THE SEASHORE.
When practice of this kind has rendered the commonest
forms familiar, it is time enough to begin serious collecting.
In the following chapters we shall consider the animals of
the shore according to their systematic position, proceeding
from the simpler forms to the more complex. This method
has many advantages from the point of view of the ana-
tomist, and is convenient for reference, but the novice when
working with actual specimens will find detailed identifica-
tions much more difficult in the case of simple forms like
Sponges than in the more complex Crustacea, for example,
which are comparatively easy to study. The shore crabs,
indeed, make a good starting-point, for they are easily found,
easily named, make in many cases most interesting and
intelligent pets, and can be very readily studied. As, further,
they all periodically cast their coats, and these coats — which
are an exact replica of the crab — are always to be found on
the beach, they are admirably suited to persons with humani-
tarian tendencies.
One other point deserves some notice. Very many people
are afraid to handle almost any shore animal, because of a
general conviction that all bite or sting. They may be
reassured by learning that in our seas there are very few
dangerous animals indeed. Apart from the true stinging-
fish, or weever, there are one or two shallow-water fish, such
as the sea-scorpions (Cottus), which are furnished with spines
strong enough to wound an incautious hand. It is perhaps
as well, therefore, not to handle living fish freely till you
know something about them. Again, the very large jelly-
fish which are sometimes to be found in the pools in autumn,
especially those of the West Coast, can sting pretty severely,
but with these exceptions almost any animal on the shore
can be handled with impunity. It is of course obvious that
the large Crustacea should be treated with discretion, for
many of them can give a pretty sharp nip ; but the wide-
spread fear of being "stung" is quite unjustifiable except
in the case of the big jelly-fish and the weever.
Finally, we may note that a tide-table is an important
part of the equipment for serious work. This may be
obtained either from a Nautical Almanack, or from most of
the newspapers published in maritime towns. Collecting is
most likely to be successful during spring tides, and should
THE STUDY OF SHORE ANIMALS. 35
be begun from five to six hours after the time of full tide.
In order to assist the beginner, a list of watering-places
which have a reputation as offering good hunting-ground to
the collector has been added to this chapter, but it should
be understood that almost every maritime village offers
facilities of some sort. The differences are chiefly differences
of degree, and in many cases a place acquires a great
reputation less on account of any outstanding merit than
because of the patient research of some particular worker,
who has given to the world long lists of animals as the
results of his shore hunting. It may be well to emphasise
the steady patience of such workers, lest the novice make
a pilgrimage to one of the places mentioned, and le
disappointed at not finding all the treasures for which the
place is famous. It should be remembered that lists such
as that of Professor Mclntosh for St. Andrews (see "Books
of Reference" at end) represent years of hard work. We shall
indicate subsequently the kinds of animals which may be
expected to occur at different parts of the coast, but may
note here that at such places as St. Andrews, North Berwick,
Dunbar, Alnmouth, Whitley, and • Scarborough, the shore
fauna has a generally northern aspect. At the very many
favourable spots on the coasts of Dorset, Devon, and
Cornwall, such as Bournemouth, Poole, Weymouth, Port-
land, Lyme Regis, Teignmouth, Torquay, Paignton, Falmouth,
Penzance, and Ilfracombe, many rare and beautiful southern
forms occur. These are also, though to a lesser extent,
present at such places as Tenby, Aberystwyth, and around
the shores of the Isle of Man ; while as we travel further
north we find in the Firth of Clyde, e.g. at Millport, or on
the West Coast, as at Oban, a certain admixture of northern
and southern forms, the latter having spread up the warm
West Coast.
CHAPTEK III.
SPONGES, ZOOPHYTES, AND SEA-FIRS.
General characters of Sponges — Some common Sponges — Characters
of the Coelentera — How to keep them alive — General account of
Zoophytes and Sea-Firs — The common Zoophytes and their
swimming-bells — The families of Sea-firs— Some common Sea-firs
— Comparison between British Hydrozoa and those of other seas
— Characters of swimming-bells.
OF the many-celled animals of the shore the Sponges are
the simplest in structure, arid therefore should logically
come at the beginning of an account of shore animals.
They are, however, far from easy to recognise and classify,
and in most cases the determination of species requires more
skill and patience than can reasonably be supposed to be
possessed by anyone but a specialist. A large part of the
difficulty lies in the fact that sponges have no conspicuous
external appendages, and no obvious organs which can be
used in classification. The classification must therefore
depend upon minute characters, especially upon the nature
of the spicules — points which are often difficult to study.
We shall in consequence confine ourselves to such an
account of British sponges as will enable the student to
know a sponge when he sees it, and to be able to name
one or two of the commonest forms.
In the first place it should be understood that sponges
are purely sedentary animals, so plant-like in appearance
that they were long thought to be plants. As in so many
sedentary shore animals, the young are minute and active.
They settle down in sheltered places under overhanging rocks,
on stones, on the broad fronds of weeds, and not infrequently
on living animals, especially Crustacea. From the places
36
SPONGES, ZOOPHYTES, AND SEA-FIRS. 37
where they once attach themselves the sponges never move.
They feed on minute particles contained in the water, which
is swept through the porous body in continuous streams.
Most of them bud freely, often forming large colonies which
spread over the rocks as lichens spread over trees. With
very few exceptions, they all contain a skeleton in the form
of fibres or sharp spicules. The colours are often variable
and bright, and as a little shore hunting will soon convince
you, sponges often have an unpleasant smell ; in this respect
they resemble the more beautiful sea-anemones, which often
give a peculiar and disagreeable odour to the dark caverns
in which some species love to dwell. Sponges can generally
be recognised by the presence of distinct pores, and the
characteristic "spongy" appearance of the substance when
torn. In some cases not a little care is required to distin-
guish them from certain compound sea-squirts, which may
contain spicules, and from Polyzoa, or sea-mats, which often
contain a large amount of lime, and are occasionally not
unlike sponges. Both sea-squirts and Polyzoa, when care-
fully examined, show the presence of "polypes," of which
there is, of course, no trace in sponges.
Without making any attempt to discuss the classification
of sponges, we may briefly note the salient characteristics
of three common forms.
By far the commonest sponge on the shore rocks is the
crumb-of -bread sponge (Halichondria panicea), which forms
a thick crust, often many inches square, over rocks and
stones in all sorts of situations. It seems to grow equally
well when fully exposed to light and when sheltered in dark
crevices, and though perhaps commonest on a flat surface
does also occur on various seaweeds, especially the stems of
Laminaria, or oar- weed, which are often completely invested
by the sponge. There are indeed few spots on the tidal
rocks where the crumb -of -bread sponge cannot obtain a
foothold. In the dry state it is commonly found on the
shore, and such dried specimens sometimes puzzle the
beginner by appearing much more " spongy " than the living
sponge as found on the rocks. This is due to the partial
loss of the soft parts which brings the skeleton into greater
prominence. In colour the sponge varies greatly; it is
often distinctly green, and at other times shows various
38 LIFE BY THE SEASHORE.
shades of yellow, brown, and drab. Dried specimens found
on the beach are always colourless. In the living sponge
the most conspicuous feature is usually the number of
openings or oscula, which stud the surface and are raised
on little prominences, but in specimens which have grown
in a spot where space is limited, as on one of the smaller
seaweeds, these oscula are less conspicuous. The surface of
the sponge is marked by a distinct network of lines, and
when its substance is torn with needles it will be found that
it is full of minute flinty spicules.
Another very common sponge is Graniia compressa, the
purse-sponge already mentioned. It is dull in tint, being
greyish brown in colour, and rarely grows -in such exposed
situations as the crumb -of -bread sponge. It is usually to
be found under overhanging rocks with the orifice hanging
downwards, and the base attached to the rock surface. It
is sac-like in shape, and in the dead state much flattened
and compressed. In life, however, the central cavity is full
of water, and the sponge is much plumper in appearance.
It is of much interest, because it was in it that Robert
Grant — after whom it is called — first discovered that in
a sponge currents of water enter the central cavity by
minute pores, and leave it by the large osculum. These
currents can be readily observed in living specimens placed
in sea-water containing solid particles in suspension. The
sponge differs from Halichondria in having a skeleton made
of spicules of lime and not of flint, and in being usually
simple, whereas Halichondria, with its many oscula, is an
example of a compound sponge. Occasionally budding
occurs, so that there may be as many as seven or eight
oscula, but the usual form is that of a slightly stalked sac
with one terminal opening. The skeleton, made of three-
rayed spicules, may be seen by teasing a little of the sponge
substance under a lens, and the fact that it is limy may be
proved by adding a drop of dilute acid, when effervescence
occurs as in the case of limestone under the same circum-
stances. The minute pores in the walls of the body are not
easily seen except in dried specimens, and even then they
are largely concealed by the spicules. The purse-sponge is
very common between tide-marks, but is usually only about
/in inch long, and is somewhat inconspicuous.
SPONGES, ZOOPHYTES, AND SEA-FIRS. 39
A smaller but much more dainty little sponge is Grantia
ciliata, a delicate silky little creature not usually more than
half an inch in length. It is oval in form, of a cream or
greyish colour, and has a crown of beautiful spicules round
the osculum. It is a solitary form and usually occurs far
out on the rocks. When examined with a lens it will be
seen that the silky appearance is due to the fact that the
surface is covered with prominences, each ending in a long
slender spicule. In life the direction of the crown of
spicules varies according to the flow of water through the
sponge; sometimes they spread outwards in a radiating
manner, and at other times they lie parallel to the long
axis of the sponge. This pretty little sponge is not very
common on the shore, and usually requires to be sought for.
These three examples may serve to give the student some
idea of sponge structure ; on certain parts of the coast,
especially on the South, other species are common between
tide-marks, but for these reference must be made to special
memoirs.
After the sponges we come to the hollow-bodied animals,
or Coelentera, which include some of the most beautiful of
our shore animals. Lovely as they are in life, both in
colour and form, they lose practically all their beauty at
death, when the majority become mere shapeless masses.
In consequence they must be studied in the living con-
dition, and this is fortunately rendered possible by the fact
that not a few will live well in confinement. This is, of
course, especially true of the sea-anemones, which make
charming pets. A few words may be said as to the best
methods of keeping the more delicate sea animals alive.
Those who have abundance of spare time, much patience,
and not a little spare cash will probably take naturally to
aquarium-keeping — that is, to the maintenance of tanks con-
taining sufficient growing plants to balance the animal life.
Even when all these requisites are present, however, the
aquarium is always liable to go wrong, and is never very
easy of management except on a very small scale. By far
the easiest method of keeping marine animals alive is in
flat shallow pans, which expose a large surface to the air
relative to the bulk of water present. A common pie-dish
of large size does well. It should only be about half full,
40 LIFE BY THE SEASHORE.
and at most should contain only two or three small animals.
If it is kept carefully cleaned, and has fresh water added to
make up for loss by evaporation, it will be found unneces-
sary to change the water for a very long period. In such
a dish many of the shore animals will live well, and there
is much more chance that you will really observe the habits
of your pets if each one has a dish to itself than if they
are placed in a crowded aquarium among many other
animals. The points of special importance are : do not
crowd, and do not use a vessel which holds a great bulk
of water proportionate to the surface exposed to the action
of the atmosphere. Some shore animals, such as the com-
mon crab, the common limpet, and others, will only live
where they are partially exposed to air, and a great number
are much more sensitive to impurities in the water than to
a partial exposure of their surface to the atmosphere.
Finally, in keeping marine animals in confinement, do not
forget that the object, as well as the justification of the
practice, is that you may observe their habits ; therefore do
not forget to look at them, to notice their changes, to draw
them if possible.
The Coelentera, or sea-nettles, as the German popular
name may be translated, form a very large group, including
a number of different kinds of animals. The most obvious
common character is the presence of tentacles, which bear
the stinging-cells to which the German name refers. Let
not the name alarm the sensitive naturalist, however, for, as
already mentioned, in this country, except in the case of
the jelly-fish and such southern forms as the " Portuguese
man-of-war," these stinging-cells will not penetrate our skin.
We may begin our study of the group by examining a very
delicate and harmless little creature, one of the zoophytes or
animals like plants. If you examine the shore pools with a
little care, you will find a number of spiral shells lying
apparently loose at the bottom, with their surface often
covered with a brown or pinkish crust. As you watch, the
apparently empty shells will move away with considerable
speed, disclosing the long legs of a hermit-crab as they do
so (see Fig. 3). Pick out the shell in which the surface
crust seems to be best marked, and drop it into a shallow
dish filled with sea-water. In a few minutes the hermit
SPONGES, ZOOPHYTES, AND SEA-FIRS.
41
will recover his equilibrium, and once more appear on his
doorstep. About the same time the dingy crust on the shell
will change its appearance, and show you a delicate waving
forest of little pink creatures, which spread out in the water
Fia. 12. -Diagram reprcs. nting the individual persons or -
zooids in a colony of Hydractinia echinata. a, nutritive
person with tentacles extended ; b, sensitive person with
ab< rted tentacles ; c, reproductive persons bearing clusters
of sporosacs. At the bases of the persons are shown the
stout protective spines. After Allman.
like miniature flowers. The whole crust constitutes a zoophyte
colony, the tiny flowers are the members of the colony, and
are called polypes, or better, zooids. We have begun our
study of the sea-nettles with a colony of this kind, rather
than with the more familiar sea-anemones, because the
42 LIFE BY THE SEASHORE.
members of the colony show the characteristic sea-nettle
shape in perhaps its simplest form. Each zooid, as the
figure shows, is like a tiny hollow column; it is fixed by
one end to the shell, while the other end, with its crown of
tentacles, floats freely in the water. Small as the tentacles
are, they still bear stinging-cells, which paralyse the prey
caught by the tentacles.
With the help of a lens and patience we can carry our
observations considerably beyond this point, and make out
that though the little zooids are similar in their broad
outlines of structure, there are marked differences in detail.
In the majority of the individuals (see diagram) the body
is long and cylindrical, ending in a mouth surrounded by
twenty to thirty tentacles. These are the "nutritive persons"
of the colony, which catch and digest the little particles
which constitute the food of the entire colony. Their
central cavities are connected with a series of canals which
ramify over the surface of the shell on which the colony is
placed, and are again connected with the central cavities of
the other zooids. By this means the food is conveyed in a
digested condition all over the colony. The other zooids
are of two kinds. Near the margin of the colony, and
overhanging the mouth of the shell, there are peculiar
long spiral individuals (marked b in diagram), which are
extraordinarily muscular and active, but are without mouth
and tentacles. The function of these "sensitive persons"
seems to be to warn the other members of the colony of the
approach of danger.' Scattered among the nutritive persons
are the third set of zooids (marked c in diagram), which are
similar to these, but only about half as high, and have
rudimentary mouth and tentacles. The special peculiarity
of these zooids is that they bear lateral clusters of sporosacs,
which are oval bodies containing eggs or male elements.
In Hydradinia echinata, as the zoophyte is called, the
sporosacs remain permanently attached to the colony, but in
very many of the zoophytes minute swimming-bells, or
medusoids, are produced instead of sporosacs, and these
swimming-bells float away, and carry the eggs to some more
or less distant spot. Finally, in Hydradinia there are
mingled with the persons a number of spines, which may
be aborted persons, and which have some protective function.
SPONGES, ZOOPHYTES, ANfD SEA-FIRS. 43
From this description of Hydradinia a general idea of
the character of the Coelentera may be gathered. The
members of the group are usually either polypes, like those
of Hydradinia, or are jelly-fish, like the swimming-bells of
many zoophyte colonies ; but both types of structure occur
in many much-modified forms. Both types not infrequently
occur in the course of one life-history, and then the phe-
nomenon which we have already studied as alternation of
generations is produced. Many forms are colonial, like
Hydradinia, and in such colonies there may be division of
labour among the members of the colony.
The Coelentera are very numerous, and are found in all
seas and at all depths ; but the different parts of the ocean
have their characteristic forms. Thus, as we all know, the
reef-building corals are confined to the warm seas, and even
in the British area there are far more sea-anemones on the
South and West than in the colder waters of the East
Coast, while certain zoophytes which occur in the North and
East are absent in the South and West.
In studying the Coelentera we shall begin with the zoo-
phyte colonies, similar to Hydradinia, which are so abund-
ant on our coast. Of these, Hydradinia is, in one sense,
a relatively simple type, for its skeleton is only represented
by the crust which covers the shell on which the colony is
placed, and by the little spines arising from this crust. In
most of the zoophytes the colony is surrounded by a pro-
tective sheath, which sometimes forms little cups in which
the individual zooids are placed. As the sheath is tough
and resistant, it not only keeps the colony expanded during
life, but also persists after the death of the zooids. These
dead colonies are often flung up on the beach, and are more
familiar to most people than the living zoophytes. From
their peculiar method of branching they are known as " sea-
firs," or are often incorrectly regarded as " seaweed." The
first class of Coelentera, therefore, includes delicate zoo-
phytes, with practically no skeleton, such as Hydradinia
and many others ; the sea-firs, with their resistant coat ;
the swimming-bells, or medusoids, which arise from many
zoophytes and sea-firs; and also some other colonial forms
much less common in our seas. This first class is termed
the HYDROZOA, and the individual zooids, or polypes, are
44 LIFE BY THE SEASHORE.
called hydroid, from their general resemblance to the little
fresh-water Hydra.
Among the zoophytes and sea-firs the character which
varies most, and which affords a basis for classification, is
the skeleton. Let us first understand what this skeleton
is, and what is its function. Both the terms "skeleton"
and " supporting substance," which one naturally applies to
it, are misleading, because both suggest the idea of support.
Now the sea-nettles do not require support for their soft
parts, because these can be, as it were, stretched by the
water which the animals take into their central cavity.
An anemone when extended, i.e. when filled with sea-water,
is firm and tense ; it is only when it ejects this water that
it collapses. The main object of the skeleton in those sea-
nettles which possess this structure must therefore be to
serve as a means of protection. Take our little pink
Hydradinia, for example. When alarmed the zooids con-
tract and cower down among the spines, so that an in-
quisitive foe darting at the floating pink things will find
them lost among these hard inedible thorns. Again, look
at any of the common sea-firs so frequent on weed. The
tiny branches are crowded with zooids, possibly edible
enough, but each of these is placed in a little cup of horny
matter. When alarmed they withdraw into the cups,
and a persevering enemy is likely to get a maximum of
indigestible horn, and a minimum of digestible zooid.
Zoophytes and sea-firs are extraordinarily numerous on the
shore rocks, and in most cases they are protected to a
greater or less extent by a horny skeleton. " ,
In the minority the skeleton is represented either by a
mere plate at the base of the colony, or by tubes which
envelop some part of the columnar body. In these naked
forms (Gymnoblastea) the individuals are often large and
highly coloured with numerous conspicuous tentacles. In
the majority of the shore forms the skeleton is greatly de-
veloped, and carries little cups, in which the zooids are
placed, and into which they can be completely retracted. In
this set, called Calyptoblastea from the cups, the individuals
are small, but usually very numerous, and the skeleton is the
most conspicuous part of the colony.
We shall mention the salient characteristics of a few of
SPONGES, ZOOPHYTES, AND SEA-FIRS. 45
the commonest naked zoophytes ; for such detailed descrip-
tion as may render the recognition of actual specimens
possible, reference should be made to the tables at the
end of the chapter.
In Hydractinia we have already described a zoophyte in
which the skeleton is very slightly developed, but there is
another pretty form in which there is even less horny
matter. This is the club-shaped zoophyte ( Clava squamata),
often exceedingly common between tide-marks. If in shore
collecting you are endeavouring to throw back the heavy
dripping curtains of bladder- wrack, which hang pendent in
front of the great rock-clefts, you may often notice little
pink fleshy spots on the weed. In-
significant enough they look, but it
is well worth your while to break off
a bit of the weed and drop it in a
clear pool. You will then find that
the fleshy mass is a dense cluster of
short stout zooids, which soon un-
fold in water and display their
characteristic club-shape (see Fig.
13). Each bears numerous scattered
thread-like tentacles, and at times,
in addition to these tentacles, one
finds that the zooids have a distinct FIG. is.— ciava squamata on
collar made up of little beads. These weed- After oilman,
are clearly shown in the figure. Each bead is a sporosac,
containing eggs, which grow directly into fresh colonies.
The individuals may reach a length of about an inch, but
the colonies never contain very many individuals. There is
no skeleton save a slight attaching plate on the weed.
As the next stage in the development of skeleton we
may mention Hydractinia where we have the spines in
addition to the basal plate. It is also remarkable because
of the fact that, as already mentioned, the colony includes
three different kinds of individuals. This " polymorphism,"
or occurrence of more than one form, is rare among the
Hydrozoa of the shore, though it commonly occurs among
those of the open sea, e.g. in the "Portuguese man-of-war"
of the South Coast.
In the next zoophyte to be mentioned we find that the
46
LIFE BY THE SEASHORE.
skeleton forms tubes in which the zooids are placed, much
as a worm lies in its tube. In examining the more delicate
kinds of weeds on the shore, a quick eye will often pick
out small yellowish tubes branching among the weed, and
bearing small zooids with numerous scattered tentacles,
remarkable in having a prominent knob at their tip,
whence they are called capi-
tate. These zoophytes are
species of Coryne and Syn-
coryne. Without going into
the characters in detail here,
let us notice one interesting
point in regard to. the repro-
duction. In all the zoophytes
described as yet we have
noticed the occurrence of
little sporosacs, structures
which lie like little fruits
on the wall of the body,
and bear the eggs from
which new colonies arise.
These are present again in
Coryne, clustering at the
bases of the tentacles, but
in Syncoryne, although the same little fruits are to be seen,
they do not set free eggs, but tiny bells of jelly, which
swim away through the water with a gentle pulsating
movement. After being set free the bells undergo various
changes, and become converted into swimming-bells, or
medusoids, called Sarsia (Figs. 6 and 15), often found near
the surface of the sea in autumn. They, together with
many other medusoids, may be caught by sweeping the
surface of the rock pools or the open bay with a fine net
on a calm day. Any medusoid resembles more or less
exactly a bell in shape, With a stalk or manubrium hanging
down in the centre to represent the clapper. We must,
however, suppose the upper part of the bell to be much
thickened, for it consists of a mass of transparent jelly,
which fills up, as it were, the upper part of the hollow of
the bell. Further, the mouth of the bell is largely filled
up by a transparent shelf which projects inwards from the
FIG. 14. — Syncoryne eximia.
After Alhnan.
SPONGES, ZOOPHYTES, AND SEA-FIRS. 47
margin, leaving only a central hole. This shelf is called
the veil, or velum. From the margin of the bell, or
umbrella as it is often called, long tentacles project, the
number varying in different forms. At the base of the
tentacles, or between them, are placed small sense organs,
often of much importance in classification. The mouth of
the medusoid is placed at the end of the clapper, and opens
into a cavity, which communicates with fine canals radiating
through the jelly of the bell. All these characters can, in
the case of some of the larger swimming-bells, be readily
made out, especially in living specimens, and on a calm
summer's day no difficulty should be experienced in obtain-
ing living medusoids. Even if a net be not at hand, it is
often possible to catch the little creatures from a boat in a
small bottle ; and there is, perhaps, no better way of study-
ing them than under such conditions, with the sunlight
playing on the water and the boat gently rocking beneath
the naturalist's feet. Then the delicate pulsating bells take
on a new beauty, and every movement displays some fresh
charm to delight the eye. It sometimes happens, on an
exceptionally calm day, that the surface
water simply swarms with medusoids of
many shapes and tints, varying in size from
tiny creatures, just discernible, as they float
along, to those with a diameter of about half
an inch. The size should be compared with
that of the large jelly-fish, which are not
very nearly related to the medusoids.
As to the special characters of Sarsia, we
may notice that in the mature stage the manu-
brium, or clapper of the bell, is very long
and thick, extending downwards considerably
below the margin of the umbrella. This
character enables one to pick out the tongued
Sarsia, as it is often called, very easily from
other swimming-bells. It, together with the
other structural points described, can be
clearly made out from the figures. In this FlQ 15 _Sargi£t
tongue, or clapper, the eggs are developed, so swimming - beii,
that while in Conjne the eggs must fall near JK *
the parent colony, in Syncoryne, by the mucks.
48 LIFE BY THE SEASHORE.
•
intervention of the swimming-bell, they are carried away
some distance from the parent colony. The swimming-bell
seems to exist only that it may perform this function of
carrying away the eggs, and in structure it is, as it were, a
zooid which has become adapted for a free-swimming life in
the open water. Like the zooid it has tentacles, but these
are few in number (only four), and relatively very long.
They hang down from the margin of the bell, and are
abundantly supplied with stinging threads. It should be
noticed that though Sarsia seems large in comparison with
the size of the zooids of Syncoryne — it may have a diameter
of three-quarters of an inch — yet its bulk is largely due to
the contained jelly, which is again largely water.
The last member of the Gymnoblastea which \ve shall
consider is the large and beautiful Tubularia indivisa, which
again produces sporosacs and not swimming-bells. It is a
form in which the stems are sometimes as much as a foot
long, and which is especially common on piers and landing
stages. It also occurs on rock surfaces and stones on the
shore, but usually near low-water mark. If, as sometimes
happens, you know that it is growing in abundance on some
rocky ledge or pier support not readily accessible with the
resources at hand, an indirect method of obtaining speci-
mens may be tried. That is, you may anchor by means of a
stone a log of wood in the vicinity of the spot, and you will
probably find that in a few weeks the log will become
covered with a luxuriant growth of zoophytes, including the
desired Tubularia. I have seen singularly beautiful speci-
mens obtained in this way. The prudent naturalist will, of
course, also not neglect such possible sources of supply as
buoys, which are often taken up regularly to be cleaned, old
boats left anchored in quiet coves, and wreckage.
One of the special peculiarities of Tubularia, by which it
is distinguished from any other zoophyte we have described,
is the arrangement of the tentacles. These are arranged in
two circles, of which the one (a in Fig. 16) surrounds the
mouth and consists of very short tentacles, while the other
(b in Fig. 16), whose members are long, is placed at a
considerable distance below the mouth. Between the two
circles are placed the sporosacs (c in Fig. 16), which in
T. indivisa are borne on branched stalks, and hang down
SPONGES, ZOOPHYTES, AND SEA-FIRS.
49
on all sides like little bunches of grapes. The colony is
invested with a straw-coloured skeleton, and as the stems
are unbranched, each resembles an "oaten pipe." The stems
are not ringed, and
narrow towards the
base, where they are
twisted and inter-
laced. The zooids are
bright pink, and pro-
ject like beautiful
flowers from their
straw-like tubes.
Besides T. indivisa
with its unbranched
tubes there are
several other species
of Tubularia, but
these come from
deeper water or are
less common. The
large size of the
zoophytes and the
beauty of their
colouring make T.
indivisa one of the
most beautiful of our
Hydrozoa. Each
sporosac contains
only a single egg,
which undergoes the
early stages of its de-
velopment within the
sac. The embryo,
when set free, has
some slight power of FlG
independent loco-
motion, and must also be readily carried about by currents.
We come next to the true sea-firs (Calyptoblastea), in
which the skeleton reaches a much higher degree of de-
velopment, and which are, above all, remarkable for their
delicate tracery. Many of them, as they spread out in the
W.— Colony of Tubularia inoivisa, showing
the zooids in their tubes. After Allman.
50 LIFE BY THE SEASHOEE.
water, show a beauty of form which rivals that of the
loveliest of ferns, while others display the coarser fir-like
appearance which has given them their common name.
The individual zooids are usually much smaller than in the
Gymnoblastea, and this fact, together with the greater de-
velopment of protective substance, gives them less beauty
of colour. One rarely finds among them those lovely rose
tints which make the colonies of Clava, Coryne, and
Tubularia so delightful to the eye. Though the individual
zooids are small, however, the colonies often reach a large
size, so that the number of individuals is enormous. The
species are difficult to identify, and the beginner must often
rest content with the genus, or even with the family. In
many cases the determination of the species requires the
aid of the microscope. On account of the number of
common forms, we shall alter slightly our usual method
of procedure, and study chiefly the characters of the
families.
A great number of the littoral forms are Campanularians
(fam. Campanularidse), and are distinguished by their bell-
shaped cups borne on the end of short stalks. The shape
and situation of these cups give the members of the family
a certain delicacy of 'form, which makes them readily
recognisable. The zooids are remarkable in possessing a
large trumpet-shaped proboscis, and generally reach a con-
siderable size. Some of the Campanularians give rise to
medusoids, others have sessile sporosacs. In both cases the
colony produces specially modified cups (gonothecse) ; but
while in the one case the cups contain sporosacs within
which the eggs ripen, in the other they open early and
allow the tiny medusoids to float away, carrying the eggs
with them. As each gonotheca may contain many medu-
soids, and the colony bears innumerable gonotheca}, it is
easy to understand how the countless medusoids found at
the surface of the sea in autumn originate. While it is
easy to recognise a Campanularian, it is often difficult to
determine the species, or indeed in some cases even the
genus. In most cases the number of teeth on the margin
of the cup, and the number of rings on the stems, constitute
important points.
Of the many Campanularians on the shore, three species
SPONGES, ZOOPHYTES, AND SEA-FIRS. 51
may be briefly described, as they are so common that almost
every patch of rocks will furnish examples. If at an ex-
ceptionally low tide you make your
way right out to the margin of the
rocks, where the great oar -weed
spreads its long fronds, or if a calm
summer day permits the slightly
dangerous experiment of a boat
among the rocks, you will notice that
the oar-weed is often covered by a
miniature forest of sea-firs. Especi- FIG. w.—OMia genicuiata on
.,, ,. , . , r weed. After Hmcks.
ally will you notice one which con-
sists of slender zigzag stems, giving off stalked cups bear-
ing tiny crystalline specks — the expanded zooids. This is
Obelia genicuiata^ seen at its best only thus in the Lami-
narian zone, but in the dead state common enough at all
seasons on the torn-off weed of the beach. It gives
rise in the summer months to countless myriads of
tiny swimming - bells, which are liberated from little
cases, or gonothecse, borne on the stems. If myriads seem
to you an exaggeration, take a few patches of the sea-fir
and make a rough computation even of the gonothecse pro-
duced by a patch of ordinary size: If your patience does
not speedily give out, you may acquire some perception of
the prodigal profusion of nature on the seashore, and of
the intensity of the "struggle for existence" which must
go on there, where so many species produce eggs numbered
in millions.
Another common Campanularian — Clytiajohnstoni — is to
be found on almost every object within the shore area
which offers a foothold — shells, weeds, stones, rock surfaces,
are eagerly taken possession of, but the back of a spider-crab
is also a dearly prized position. Almost any spider-crab
taken at random will show you the simple unbranched
stalks of Clytia, each ending in a solitary bell, but you
should also look for it on rock surfaces, as a good means of
training the eye. It is by no means a conspicuous object.
Let us mention one other common Campanularian which
is also to be found everywhere between tide-marks. This is
Campanularia flexuosa, which often grows, intermixed
with weed, in patches of great extent, and can be recognised
52
LIFE BY THE SEASHORE.
by the large cups
and characteristic
" flexuous" branch-
ing. The figure
shows its general
characters very
clearly. Together
with the two pre-
ceding species it
serves to indicate
the characters of
the family, and
being not incon-
spicuous, is of
some importance
in giving rock
pools their char-
acteristic appear-
ance. Though the
sea-firs must, on
account of their
horny skeleton, be
somewhat indi-
gestible, yet they
are eaten by at
least the sea-slugs.
They also serve
as shelters for
hosts of the more
delicate animals,
many of whom
pass their lives
clinging to their
branches. The
forests of Cam-
panularians are
therefore worth
a little study,
Fio. 18.— Magnified representation of a branch of even if Only for
Campanularia flexuosa. a. empty cup ; b, cup with J.T • rpQ<3mi
expanded zooid; c, gonotheca. Note the ringed tm L<-««SUII.
"flexuous" stem. After Hincks. Though to the
SPONGES, ZOOPHYTES, AND SEA-FIRS. 53
beginner it may seem that the sea-firs are less interesting
than some of the more "lively" of the shore animals,
we shall rapidly review all the more important families,
partly because they afford most interesting examples of
progressive evolution, and partly because the study of
them constitutes an admirable training in minute accuracy
of observation. A wet evening spent over a handful of
sea-firs, studied with the aid of the low powers of the
microscope or a good lens, will be found of great value
to anyone at all interested in species work.
A very insignificant little sea-fir — Opercularella lacerata —
may serve to indicate the characters of the family Campa-
nulinidse, which represents the process of transition from
the Campanularian condition to that found in other families.
This sea-fir has stalked cups, but they are not bell-shaped,
but ovate and conical, while the zooids are cylindrical with
a short proboscis. A special peculiarity is that the cups can
be closed by an elaborate lid, or operculum.
The next stage in the transition from the Campanularian
condition is seen in the family Lafoeidae, where the cups are
tubular and almost without a stalk (sessile). The only
example we shall consider is Lafoea dumosa, which occurs
both on the shore and in deep water. It may reach a
height of four inches, and is then erect and irregularly
branched, but the specimens found between tide-marks are
usually small and have simple creeping stems. The tubular
cups are very numerous and spring from all sides of the
stem. The whole colony has a yellowish tint.
One other small transitional family must be mentioned,
which includes the curious "herring-bone coral," a species
often cast up on the beach, and occasionally found between
tide-marks. The whole colony is figured on page 319. It
is a large form, sometimes reaching a height of ten inches,
and is peculiarly stiff and rigid, differing in this respect
from the majority of the plant-like sea-firs. The Latin
name of this form is Halecium halecinum, and it belongs to
the family Haleciidse. The special peculiarity is that the
cups are sessile, and are placed in two rows on the stem (see
Fig. 19). This recalls the conditions seen in the next
family, the Sertularians ; but there the cups are let into
the stem, while those of Halecium are placed on a project-
LIFE BY THE SEASHORE.
ing process, and are tubular or almost campanulate. The
stem is much branched, after the fashion called pinnate,
and the cups are alternate.
The next family is that of
the Sertularians (Sertularidae),
which includes a large number
of forms, usually easy to
recognise, and represented
both in the living condition
on the rocks, and among the
dried wreckage of the shore.
The cups are entirely sessile
and are sunk in the stem, the
result being to give the stem
and its branches a character-
istically stout appearance as
compared with the filmy
threads of many of the Cam-
panularians. The cups usually
occur on both sides of the
stem, and the zooids are com-
pletely retractile, so that after
death they are rarely visible.
The first genus of this
family is Sertularella, which
contains one or two not uncommon littoral forms. We
shall describe only one species, chosen because it is not only
widely distributed round our own coasts, but also occurs in
most seas. This is S. polyzonias, a pretty straw-coloured
zoophyte, which often reaches a considerable size. Like all
the members of its genus, it has its little cups placed al-
ternately, and this, together with their shape, gives a
peculiar and characteristic appearance to the whole colony.
Each cup has a toothed margin, and can be closed by an
operculum made of several pieces. The different species of
the genus are distinguished especially by the shape of the
cups. In S. polyzonias these are urn-shaped, and bulging
below with a divergent four-toothed aperture. In fact, they
somewhat resemble the calyx of the Figwort. The stems
are slender and much, but irregularly, branched.
From the species of Sertularella it is usually easy to
FIG. 19. — Magnified fragment of a
branch of Halecium, showing the
peculiar tubular cups ami the ex-
panded zooids. After Hincks.
SPONGES, ZOOPHYTES, AND SEA-FIRS. 55
distinguish at a glance the species of Sertularia, which have
usually opposite cups, and stems which appear to be made
up of a succession of triangular joints, the base of the
triangle being directed upwards. By far the commonest
species is S. pumila, an insignificant little zoophyte, which,
with its loosely branching stems, often occurs in great pro-
fusion on the shore rocks. It has a special preference for
the blades of the larger weeds, and is readily recognised by
the regular V-shape of the joints of which the stem is
composed. The cups in which the zooids are placed form
FIG. 20. — Sertularia pumila, and a magnified representa-
tion of a portion of a branch, a, gonotheca ; &, empty
zooid-cup. After Hincks.
the upper part of the diverging arms of the V (see Fig. 20).
We may repeat here that to recognise the species of sea-firs
requires a little skill and the use of the microscope. The ex-
amples which have been briefly described are intended to
give the student some notion of the modifications of structure
seen in the chief families, and assist in the recognition of at
least the family of the common forms. More than this will
probably be found difficult for the beginner. Several species
of Sertularia are fairly common between tide-marks, and
others are frequently thrown up on the beach, and are to
be found attached to other animals so thrown up. To settle
the species of these is often difficult, but it is much to learn
that they are Sertularians, and to realise their differences
from the other hydroids often so plentiful in the same place.
Before we leave the family two other forms may be
briefly mentioned, which differ very much in appearance
56
LIFE BY THE SEASHORE.
from other Sertularians. Both do occur occasionally in the
Laminarian zone, but are most commonly found among the
shore wreckage. There their peculiar shapes have made them
both noticeable objects, and have given to the one the name
of " sickle-coralline " and to the other that of " bottle-
brush." So remarkable is the resemblance of the latter to
the object indicated in its common name, that people fre-
quently refuse to regard it as an animal production at all.
First as to the "sickle-coralline" (Hydrallmania falcata).
It is a large form, reaching a height of a foot or more. Its
general appearance may be described in the
words of Sir John Dalyell as "a series of
feathers implanted in spiral arrangement round
a slender stem," but when dried the "feathers,"
or "plumose branches," become curved or sickle-
like. The zooid-cups are placed on one side of
the pinnas only, a fact which makes the whole
zoophyte resemble the next family — the Plumu-
Iarida3 — rather than the other Sertularians.
Further, they are placed in clusters on each
joint of the stems, and are tubular in shape.
The "sickle -coralline" is a zoophyte which is
very likely to be mistaken for "seaweed."
The "bottle-brush" (Thuiaria timid] cannot
be honestly described as anything but ugly. It
consists of a long naked stem with a small
"brush" at the top, and is of a dull brown
colour. It may attain a height of twelve
inches, but specimens of six to seven inches
are more common. The brush varies in size,
but not infrequently occupies about one-third
of the stem. As the stem grows and branches at
the top, the lower branches fall off, so that the
brush does not necessarily increase in size with
the growth of the colony. In consequence, further,
of this method of growth, the naked portion of
the stem shows throughout the scars where the
old branches have fallen off. The botanist will
rTifiaria a^ once perceive the resemblance in method of
thuia. After growth to a tree-fern, or to many palms. The
cups containing the zooids are so sunk into the
SPONGES, ZOOPHYTES, AND SEA-FIRS.
57
substance of the branches as to be discernible only with
difficulty. They are arranged in two rows.
The last family of the Calyptoblastea is the Plumularidae,
including some of the most delicately beautiful of the
zoophytes. Most are beautifully and elaborately branched,
so as to produce "plumes" rivalling those of the most
delicate ferns (see Fig. 9, p. 29). In all the cups are
sunk into the branches, and are placed on one side of the
branches only. As they are usually small, one result of
this arrangement is to make them very inconspicuous, so
that to the unaided eye there is nothing to destroy the
plant-illusion. The gonothecae always contain fixed sporo-
sacs. A final peculiar character is that the colony bears,
in addition to its zooid-cups, much smaller cups, called
nematophores, which contain stinging- cells. These are
usually very minute, and require the aid of the micro-
scope before they can be seen. Of the Plumularians
we shall describe one example only, the delicate little
Plumularia setacea, which is quite common on the shore
rocks. Its graceful plumes reach a height of over an inch,
which is not small for a littoral zoophyte, but their texture
is so delicate and fragile
that they are not easily
seen. Each tiny plume
rises independently from
the creeping stolon, and
is so transparent that,
except when the white
reproductive capsules are
present, it requires a
quick eye to discern it.
The special peculiarities
of the species lie in the
minute structure of the
pinnas, or branches.
Examined with the
microscope these will be
found to consist of joints
which are alternately
long (d) and short (e),
and of which the longer
FIG. 22.— Magnified branch of Plumularia.
The letters are explained in the text.
58 LIFE BY THE SEASHORE.
only bear zooid-cups (a), a single one to each. Above each
cup are two minute cup-shaped nematopliores (£/), while
beneath each is a single one (b"). The short joints also bear
a single nematophore, but no zooid-cup. Other nematophores
occur at the joint of origin of the pinna3, and on the main
stem (b"r). The gonothecaB (c) arise at the angle between
pinnaB and stem, and are remarkable for their long tubular
necks.
The Calyptoblastea are so abundant on the shore that
even at the risk of wearying the reader, we may briefly
review the different families. Sea-firs which bear distinct
bells borne on stalks belong to the Campanularians, which
have large zooids, and vary much in their branching.
Where stalked cups occur which are not bell-shaped, but
ovate and conical, the colony must be referred to the
Campanulinidse ; but if the cups are numerous, tubular,
and without a stalk, then the specimens belong to the
LafoeidaB. In the " herring-bone coral " the cups are similar
and also without a stalk, but they are arranged in two rows
at the sides of the flattened stem. In the Sertularians the
deeply sunk cups, the jointed stems, and the arrangement
of the cups make the colonies resemble some firs, or the
backbone of a little fish. Finally, the Plumularians are like
little feathers, and have their cups placed at one side of the
stem only.
From this survey of the littoral Hydrozoa we may gather
a general idea of the special peculiarities of these curious
and beautiful animals. All the forms we have considered
are colonial, living in communities often formed of an enor-
mous number of individuals, which are mutually dependent,
and are connected by a ramifying series of canals. In
the next group of Coelentera — the sea-anemones and their
allies — this colonial habit is less common in our seas, though
even there colonies quite analogous to those of the sea-firs
do occur. Again, except in Hydmctinia, we have found
that the individuals of the colonies show little division of
labour; we have nutritive persons, or hydroid polypes, and
reproductive persons, sporosacs or swimming-bells, but with
the exception already made, the hydroid members of any
colony are all similar. Now in certain free-living Hydrozoa,
which are abundant in warm seas, but very inadequately
SPONGES, ZOOPHYTES, AND SEA-FIRS. 59
represented in our own, division of labour is carried to a
much greater extent than in Hydractinia, and we have
floating colonies formed of many different kinds of persons.
These constitute the Siphonophora, and are exemplified by
such forms as the " Portuguese man-of-war," which is some-
times brought by the Gulf Stream to certain parts of our
coast.
Another interesting point about our littoral Hydrozoa is
that, as we have already pointed out, they show a consider-
able range of variation in regard to the power of forming
a skeleton. While some, like Clava, form scarcely any
skeletal substance at all, in others, as for instance the
"bottle-brush," the tough coat is much more conspicuous
than the living zooids. But whether the coat be well
developed or not, it should be noted that it is always
horny, and never made of lime. There are a few Hydrozoa
which form limy coats (corals), but these do not occur
round our coasts.
Lastly, we should note the relation of the zoophyte
colonies to the tiny swimming-bells so abundant in our
seas in late summer and early autumn. We have seen that
these medusoids arise from zoophyte colonies, and are the
reproductive persons of those colonies, and we have seen
also that while some zoophytes give rise to medusoids,
others bear sessile sporosacs. In some cases, as in the
Sertularians and Plumularians, this latter condition prevails
in a whole family ; while in other cases, as in the Campanu-
larians, closely related forms display the two conditions.
There seems no doubt that the production of swimming-
bells is the more primitive condition, and that this power
has been lost by such families as the Plumularians and
Sertularians. Probably its loss is associated with the fact
that the bells are very liable to be swept away by strong
currents to localities quite unsuitable for the hydroid stages,
and that distribution by means of minute larvae is as
effective and much less costly than the production of
swimming-bells. Nevertheless, we have forms like Obelia
geniculata and Campanularia flexuosa, which seem to live
under quite similar conditions, and are both extraordinarily
abundant; and of these one bears sporosacs and the other
true medusoids. Therefore, though we have much reason
60 LIFE BY THE SEASHORE.
to believe that the condition of each is an adaptation to its
own particular surroundings, yet we are unable to say how
the surroundings differ, or wherein the adaptation consists.
Nor can we say that the difference is associated with some
other structural peculiarity, for as yet it is not possible to
point out any constant difference between those zoophytes
which produce medusoids and those producing sporosacs,
apart from this prime difference. It is the constant occur-
rence of phenomena like this which makes shore life so
interesting, and its study so helpful to those especially
whose scientific training has been largely that of the
laboratory.
Though we cannot tell whether a hydroid colony will
produce sporosacs or medusoids, apart from the actual
experience which shows us what it does produce, yet it is
interesting to note that there is a permanent structural
distinction between the swimming-bells of the Calypto-
blastea and those of the Gymnoblastea, so that we can
determine the nature of the colony from which any par-
ticular swimming-bell has arisen. We cannot here describe
in detail these differences, but may note that in the former
case the reproductive elements are produced in the rnanu-
brium, or clapper of the bell (cf. Sarsia), while in the latter
they arise in the course of those radial canals of which
mention has been made (p. 47). Both kinds of medusoids
are common in our seas, but in most localities those of the
species of Obelia are perhaps commonest of all. They may
be recognised by their peculiarly flattened shape, and the
short distinctly four-lipped manubrium. The tentacles are
short and numerous, and the four sets of reproductive
organs are very distinct. The size varies from about that of
a sixpence to that of half a crown, and the creatures resemble
transparent plates rather than bells. Another very common
swimming-bell, that of Clytia johnstoni, is shown in Fig. 90,
p. 326. It differs chiefly from that of Obelia in having only
four tentacles.
We shall conclude this chapter by giving a table which
may assist the student in the identification of the common
sea-firs.
SPONGES, ZOOPHYTES, AND SEA-FIRS. 61
CCELENTERA. — Hollow-bodied animals with tentacles and sting-
ing-cells.
Class I. — HYDROZOA.
Sub-class. — HYDROMEDUS^;.
Order I. — GYMNOBLASTEA. Zoophyte colonies in which the horny
investment, if present, does not form cups for the zooids.
Tentacles scattered and
Tentacles thread-like.
very numerous. J ava"
Tentacle in two circles. Tulularia.
Tentacles in one circle.
. ^
Zooids not all similar. )
{Colonies produce sessile \ „
sporosacs. / oryne
Colonies produce free ^
medusoids (Sarria). )
CHARACTERS OF SPECIES.
Clava. Two common species, C. squamata forming dense clusters on
weed, C. multicornis with scattered individuals usually on
stones.
Coryne. A common species is C. piisilla, a small, rather delicate
species, with slightly branched stems marked with rings.
Tentacles, about thirty, in many circles ; zooid long and
slender, scarcely tapering below.
Syncoryne. A common and conspicuous species is S. eximia which
forms bushy tufts on weeds. Stems often several inches in
length, smooth save for a few annuli at the base, profusely
branched.
Tubularia. In T. indivisa the stems are long, unbranched, and
smooth. Between the upper and lower circle of tentacles are
inserted the grape -like bunches of sporosacs.
Hydradinia. In H. echinata the colony forms a pinkish crust on
shells inhabited by hermit-crabs. For description see text.
Order II. — CALYPTOBLASTEA. Sea-firs, in which the zooids are
placed in horny cups.
CHARACTERS OF FAMILIES.
Fam. Campanularidee. ( Cly*ia> Obelia, Campanularia are not dis-
Cups bell-shaped and \ ting™shed by any peculiarity of the
stalked colonies as a whole, but only by their
I reproductive persons (see pp. 50-52, 60).
Fam. Campanulinidfe. } „ 7 n W.LI. j- ,
Cups ovate and coni- Opercularella. With a distinct operculum
calf stalked. J («ee below).
62
LIFE BY THE SEASHORE.
Fam. Lafoeidse. Cups
tubular and sessile.
Fam. Halecidse. Cups
in two rows, tubular
and sessile, borne on
projecting processes of
stem.
Fam. Sertularidte. Cups
sessile, sunk in the
stem, usually in two
rows.
Fam. riumularidfe. Cups
sessile, on one side of
stem only, "nemato-
phores" present.
Cups very numerous, springing
from all sides of the stem.
Halecium. Stems peculiarly stiff and rigid.
Cups alternate, with \
toothed margin and Y Sertularella.
an operpulum.
Cups opposite, stem |
made up of V-shaped j- Sertularia.
joints. J
Cups tubular, on one \
side of stem only, in j- Hydrallmania.
clusters.
Cups deeply sunk, \
branches confined to V Thuiaria.
upper part of stem. J
Plumularia. Nematophores distributed
along the stem and branches.
CHARACTERS OF REPRESENTATIVE SPECIES.
Fam. Campamilaridce.
Genus Obelia. Contains a number of species, of which the com-
monest is Obelia geniculata. Height about one inch. Stems
upright, zigzag, connected at base by creeping stolons,
jointed, with stalked cups at the joints. Margins of cups
smooth, stalks ringed.
Genus Clytia. In Clytia johnstoni, which is very common, the
stems bear a single terminal cup. Stems ringed at top and
bottom, but not in middle ; edge of cup with ten to twelve
teeth. Gonothecce either on stems or on basal stolon.
Genus Campanularia. The commonest species is Campanularia
flcxuosa. Stems slender, branched, flcxuous, about one inch
high. Cups large, tapering below, with long ringed stalks.
Gonothecre large.
Fam. Campanulinidce.
Genus Opercularella. In 0. lacerata the stem is under one inch in
height, erect, slender, ringed throughout ; cups few, on ringed
stalks. Cups with segmented margin, the segments being
capable of closing over the opening like a lid (operculum).
Gonothecce large.
SPONGES, ZOOPHYTES, AND SEA-FIRS. 63
Fam. Lafoeidse.
Genus Lafoea. In L. dumosa height may reach four inches, stems
erect and irregularly branched, or simple and creeping, cups
tubular and numerous, arising from all sides of the stem.
Fam. Halecidce.
Genus Halecium. In H. halecinum ("herring-bone" coral) height
may reach ten inches. Stems rigid, much branched. Cups
sessile in two rows on projecting processes, alternate, tubular.
Gonothecfe on upper surface of stems, broad and truncate
above, with tubular orifice at side.
Fam. Sertularidoe.
Genus Sertularella. In S. polyzonias the cups are urn-shaped,
bulging below, with a divergent four-toothed aperture. Gono-
tliecre shortly stalked and large. Stems slender, much but
irregularly branched.
Genus Sertularia. In S. pumila the sterns are loosely branched,
the gonothecse have a tubular rim.
Genus Hydrallmania. In H. falcata ("sickle -coralline") the
stems are about a foot long, slender, and with spirally-
arranged branches. Gonothecae yellow and tubular.
Genus Thuiaria. In Thuiaria thuia ("bottle-brush") the stem,
which may be one foot in length, bears a cluster of branches
at the top. Cups in two rows.
Fam. PlumularidtB.
Genus Plumularia. In P. setacea the slender, delicate stems are
about one inch in height, the plumes arise separately from
the creeping stolon. Joints of branches alternately long and
short, zooid-cups placed singly on the long joints. For
nematophores, see figure. Gonothecoe with long tubular
necks.
NOTE ON DISTRIBUTION.
The Sponges and Sea-firs described in this chapter are so common
that they may be expected at almost any part of the British area,
where the conditions are at all favourable. Their relative abundance
at different places varies considerably, however. Thus Hydractinia
echinata, which is extraordinarily abundant at St. Andrews and in
the Firth of Forth, is much less common in the South and West.
Again, at places like Torquay and Penzance, not only may many
other species be expected on the shore in addition to those mentioned,
but a happy chance may furnish the "Portuguese man-of-war"
(Physalia), to which reference has been made above, and other beau-
tiful free-swimming forms, swept in by ocean currents from the open
sea. Though generally vspeaking the South and West are richer in
Hydrozoa than the North and East, yet there are one or two forms
which occur in the latter and not in the former localities. The
interesting "bottle-brush" (Thuiaria thuia}, for example, is said to
be rare off the coasts of Cornwall and Devon.
CHAPTER IV.
SEA-ANEMONES AND THEIR ALLIES.
Differences between sea-anemones and zoophytes— Four common sea-
anemones, their habits and characters — Variation in sea-anemones
— "Dead men's fingers" in life and after death — The sea-pen —
The Jelly-fishes— Life-history of Aurelia— Relation to Lucenaria—
The Ctenophora, or "iridescent fire-globes."
SO far we have been concerned with the simplest of the
Coelentera, where any complexity which may occur is
the result of the combination of individuals, and not of the
characters of the individuals themselves. Furthermore, as
we have repeatedly emphasised, the individuals are always
small, often very small, and alternation of generations is
always clearly indicated, though there is a tendency for it
to become suppressed. In all the cases we discussed where
the alternation disappears, it is the active medusoid stage
which is lost. The second class of Coalentera, which we
are to consider in this chapter, is in many respects very
sharply contrasted with the Hydrozoa. The individuals are
often large ; colonies, in our seas at least, are relatively less
frequent; the structure of the individual is more complex
than in the Hydrozoa; there is either no trace of alternation
of generations, or, where it occurs, the active jelly-fish stage
tends to be accentuated at the expense of the stationary
stage. This class is often called the Scyphozoa, and is held
to include the sea-anemones and their allies (Anthozoa), and
the big jelly-fish. By some authorities, however, the jelly-
fish are placed in a separate class. As we shall be very
little concerned with the jelly-fish we need not discuss the
question of their position, but may merely emphasise their
distinctness from the swimming-bells of the Hydrozoa,
which are much smaller and less complex.
64
SEA-ANEMONES AND THEIR ALLIES.
65
Of the Scyphozoa the most interesting to most people are
undoubtedly the sea-anemones, with which we may con-
veniently begin. The anemones are almost always beautiful
and brightly coloured, they live well in captivity, they are
common and conspicuous; facts which easily explain their
popularity, even with persons who shrink from sea animals
in general as always slimy and possibly noxious. Their
popularity has been assisted by the fact that in Gosse's
British Sea-anemones and Corals we have a readily accessible
book which, from its wealth of illustration and clear
descriptions, enables the veriest neophyte to name his finds.
Unfortunately, the anemone-lover whose habitation chances
to be on the East Coast is not likely to find a great variety
of forms. While the rocky, wave-swept shores of Devon
and Cornwall are often veritable gardens of sea-flowers, our
sandy beaches produce a few species only, and these the
commonest and hardiest kinds. On the shore rocks of the
East Coast we cannot hope to find more than four species,
and among these we miss the beautiful Anthea cereus, which
at so many spots on the South and West flourishes in
gorgeous beauty between tide-marks.
We may take first the most abundant and obvious of all
our native anemones, the smooth anemone (Actinia mesembry-
anthemum, Fig. 23), which can live everywhere and any-
where, asking only a firm basis of attachment, and a situation
between tide-marks. If you find a clear pool containing a
specimen in full expansion you may proceed to study the
general characters of sea-anemones. The general " polype "
shape is of course
obvious, the body con-
sisting of an attached
base, an upright
column, and a disc
bearing a central
mouth surrounded by
numerous tentacles.
Touch the tentacles
with your finger, and
you will find that
they have a peculiar FIG. 23. — Common smooth anemone (Ac'inia
Stickv feelino- dllP to mesembryanthemum). Note the beads at the
J o> "• base of the tentacles.
66 LIFE BY THE SEASHORE.
the ejection of their numerous stinging-cells, which are
too weak to pierce the skin. When molested the anemone
a1 es not shrink down in the way in which the hydroid
Dphytes do, but contracts a circular muscle at the top of
B column, and pulls the tentacles inwards at the same
ae. The result may be compared to the closing of a bag
drawing a string run in its margin. The mouth is a
longitudinal slit, whose walls are much grooved. Of the
grooves two are more distinct than the others, and con-
stitute the " siphonoglyphes." which are structures of
considerable interest to the student of form. It is not
easy to get a practical notion of the internal anatomy
of a sea-anemone without subjecting it to special treat-
ment; but sometimes some of the more transparent
species can be studied in the living condition by holding
expanded specimens in a glass jar up to the light. The
more important points may be briefly summarised as follows.
The mouth opens into a short gullet, which itself opens
into the general cavity ; this gullet can be clearly seen when,
as often happens, captive anemones partially turn themselves
inside out, and is produced by an infolding of the body-wall.
The gullet does not hang freely in the general cavity, for a
number of partitions or mesenteries run from it to the
body-wall, so that a cross-section of the upper part of a
sea-anemone would show a central chamber surrounded by
radial chambers. These radial chambers are traversed by
other narrow mesenteries which project from the body-wall,
but do not extend inwards so far as the gullet. On the
mesenteries are borne the reproductive organs, and also
certain tangled threads, supposed to be of importance in
digestion. These are often seen when an anemone is
ruptured in the attempt to remove it from a rock surface.
In certain anemones, but not in the smooth anemone,
the mesenteries also bear long, slender threads, crowded
with stinging-cells, and capable of being shot out by
pores in the body-wall. In Actinia these acontia seem
to be functionally replaced by the " batteries of stinging-
cells," which form the row of blue beads visible at the
base of the tentacles. The chief points of contrast
between a sea-anemone and a hydroid polype are : the
presence in the former of a distinct gullet, of mesenteries
SEA-ANEMONES AND THEIR ALLIES. 67
lamerrts,'
or partitions, and of "digestive filamerrts," the tangled
threads mentioned above.
As to the special characters of Actinia mesembryan-
themum, note the very smooth column, which is always
short relative to its diameter; the rather short tentacles,
which number about 200, and usually in the expanded
condition curl over the margin of the disc. The mouth is
elevated on a blunt cone, and the row of blue beads is very
characteristic. There is always a narrow blue edging round
the base, but in the other parts of the body the colours are
very variable. The three common tints are dark red, olive-
brown, and green, but in many cases the column is streaked
and spotted with lighter colours. This anemone lives well
in captivity, and then often gives rise to numbers of tiny
semi-transparent young, which make the daintiest of pets.
As sea-anemones are so familiar, it is, however, probably
unnecessary to expatiate on the habits at length. Gosse
names and describes a number of varieties of the smooth
anemone, but perhaps the most important point for us is to
emphasise the great adaptability of sea-anemones in general.
They are, of course, of relatively low organisation, and seem
capable of varying in harmony with their environment to a
very marked extent. The variability is often displayed by
modification in colour, which we have, perhaps, no reason to
regard as adaptive, but it is also often shown in other
characters. This is well seen in the next sea-anemone,
Tealia crassicornis, the thick-horned anemone, which in
abundance comes only next to Actinia. It inhabits both
deep and shallow water, and between tide-marks sometimes
lives in rock pools which never become dry, and at other
times under overhanging rocks among gravel and sand. In
these different situations it exhibits noticeable structural
differences, while of colour differences there is an almost
endless variety.
What may be called typical specimens are to be found
under sheltering stones where the sun does not reach. At
low tide the anemones form an almost indistinguishable
mass of stones and shell fragments, but are yet sufficiently
alive to squirt vigorous jets of water at an intruding
naturalist, at the same time cowering down yet more closely
among the debris. If an attempt be made to remove the
68 LIFE BY THE SEASHORE.
specimens, it will be found that they are attached, not to
one smooth surface, but to a number of objects, in a fashion
that makes them difficult to extricate without injury.
Further observation in a neighbouring pool will probably
disclose some other fully expanded specimens in which the
characters can be studied. The anemone is characterised by
the size of the base as compared to that of the column ; it is
a low, flattened animal, with a diameter often of several
inches. The tentacles are short, very thick, and not
numerous ; they have none of the snaky appearance usually
FIG. 24. — Tealia crassicornis, the thick-horned anemone. Note the central
mouth, and the stout, banded tentacles. After Tugwell.
associated with anemones' tentacles. The surface of the
column is covered by distinct warts or papillee, to which
shells and stones are attached. The colours vary, but reds
and greens are common, while the tentacles are banded
with white, and have very distinct reddish bands round
their bases, which extend over the disc towards the mouth.
Though the majority of the thick-horned anemones found
between tide-marks are of this type, yet in those narrow
rock-clefts which are swept clean by the tidal currents
but never completely emptied, another variety occurs. At
North Berwick, for example, the shore rocks are hollowed
out into many fissures and crevices, and it frequently
happens that a cleft, which from above seems narrow
enough, widens out below into an extensive deeply shaded
SEA-ANEMONES AND THEIR ALLIES. 69
pool. If by any means you can wedge yourself down the
cleft, and obtain a foothold in the cavern beneath, you
may see dozens of specimens of Tealia crOSsicornis in full
expansion, and in almost every variety of tint. They
attach themselves to the perpendicular rock-walls, and,
apparently as a result of this mode of attachment, show
a much more typical " anemone-shape " than their flattened
brethren of the tidal pools. That is, the column reaches a
height equalling the diameter of the disc, and is truly
columnar; whereas in the other form it is short or squat.
Again, these deep pools contain no shell sand or gravel,
and the anemones are in consequence destitute of covering,
while the functionless warts have become small and incon-
spicuous. The colouring is brilliant, and it not infrequently
happens that the tentacles are uniformly coloured through-
out, or have merely a paler spot near the tip. In the
commoner form they are distinctly banded, which, from the
artistic point of view, is a much less effective scheme of
coloration. A colony of such anemones, all of large size
and all in full expansion, forms one of the most beautiful
of the many beautiful sights of the shore, and I know
few more fascinating occupations than that of successfully
forcing one's self into these caverns, and while maintain-
ing a somewhat uncertain foothold on the slippery sides,
studying every detail of colour and form. The roar of the
breakers at the mouth of the cleft, and the rush of water,
now in and now out, adds the spice of danger to the
occupation which is essential to fill up the tale of pleasur-
able sensations. These anemones, unlike those in shallow
pools, are easily detached without injury, but they rarely
live well in captivity; they doubtless miss there the
abundantly oxygenated water of their natural habitat.
If the t de permit it is easy in that natural habitat to
make observations on the diet. In spite of their frequently
fragile appearance the anemones in general are far from
having fairy appetites, and Tealia is especially voracious.
It seems to have a special preference for crabs, and may
often be seen disgorging the remnants of its victims. In
a quiet pool, indeed, I have seen a regular heap of dejecta
beneath the anemone — a veritable kitchen midden on a small
scale. It is interesting to note that the colour of the shell
70
LIFE BY THE SEASHORE.
of the shore crab is changed by the digestive process from
greenish to red — a change which it is easy to imitate in the
laboratory by immersing a fresh shell in dilute acid. Also,
the hard shell has been rendered brittle and is easily
pulverised. From these observations we might deduce the
conclusion — which has, indeed, been reached by experiment
— that the anemone secretes an acid digestive fluid.
Next in order of abundance on the East Coast comes the
cave-dwelling anemone (Sagartia troglodytes}, a form which
in spite of its
abundance is much
more difficult to
find than either
of those already
mentioned. If you
are idly gazing into
a shallow rock pool
floored with varie-
gated sand or fine
gravel, you may
sometimesfindthat
as you gaze certain
FIG. 25.— The cave-dwelling anemone, Sagartia troglodytes, star-like patches
Note the beautifully marked tentacles, and especially differentiate them-
selves from the
background by a regularity of shape, not to be ascribed to
current action. If you touch these spots in order to
investigate the matter, the star disappears, leaving an ill-
defined hollow. Study this phenomenon still more closely
by scraping the sand away with your fingers, and you will
find a small sea-anemone, attached to the rock surface which
floors the pool, and protruding its crown of tentacles through
the sand. The attachment is relatively slight, and the
anemone can be readily removed and placed in a clean pool
or a collecting jar. It is very contractile, and by the time
the process is completed will probably be reduced to the
condition of a brownish button, partially invested in its
own white stinging-threads (acontia), which are shot out in
abundance as soon as it is touched. It rapidly recovers,
however, and will probably soon unfold its tentacles, and
display the variegated marking which gives them so deceptive
SEA-ANEMONES AND THEIR ALLIES. 71
a resemblance to sand. The column is long, often very long,
and cylindrical, and in its upper two-thirds is covered by
distinct suckers, to which fragments of stone and shell are
often attached. On the other hand, in a sandy pool it is
not uncommon to find specimens which, instead of being
covered with isolated fragments of gravel, have a complete
investment made of fine sand glued together by mucus.
This can be peeled off, and leaves the smooth column below.
The cave-dweller does not always live in sandy pools, but,
as the name indicates, is often found in rock crevices.
There the colours are brighter, the prevailing tint being
greenish brown or grey-violet. They are also often abundant
in the beds of young mussels which sometimes cover the
flat surfaces of rocks. The young mussels are, as it were,
embedded in a thick layer of silt, which intervenes between
them and the rock surface. The anemones are attached to
the rock like the mussels, and protrude their starry crowns
through the layer of silt, while the shells of the mussels
make a firm wall around them. If you look at such a young
mussel-bed from a distance of a few feet, you will notice
that the uniformity is interrupted by numerous rounded
spaces, in which the silt and sand show out in contrast to
the dark shells of the surrounding mussels. A close
examination will show you that each gap is occupied by a
flourishing Sagartia troglodytes. The sight is an interesting
one, and suggests many problems. What does the anemone
gain from the association? Is it a true case of an "animal
association," or is it merely a chance that the same environ-
ment should suit both? Does the anemone obtain any of
those benefits somewhat vaguely summed up in the word
protection, or is it that it shares the food of the mussels'?
These are only a few of the questions one would like
answered.
The cave-dweller lives so well in confinement, and its
markings so well repay study, that a few should be taken
home for the purpose. In one habit it differs remarkably
from the two preceding anemones. They will rarely expand
freely unless the base is firmly fixed, and as every aquarium
keeper knows, they will never thrive unless they can be
persuaded to attach themselves almost at once. The cave-
dweller, on the other hand, rarely completely retracts its
72 LIFE BY THE SEASHORE.
tentacles, and will often expand fully while lying loose in
a jar. It never fixes itself very firmly, and the "cave-
dwelling " habit is no doubt associated with the fact that it
seems unable to cling tightly enough to resist wave-action,
and must therefore seek protected crevices.
y\s to p,r>1nrfl.t,inTiT though the actual tints of column, disc,
and tentacles show much variation, yet there is considerable
constancy in the markings, which constitute important
specific characters. The column is marked with light
stripes most conspicuous towards the base, the disc is
beautifully marked with radiating bands, each band being
patterned in dark and light tints, and at the base of the
tentacles there is a black mark of the shape of a B, the
curves being directed towards the mouth. This B-mark is
eminently characteristic of Sagartia troglodytes. Finally,
the tentacles themselves are banded in dark or light tints,
and are of much importance in producing the resemblance
to sand so characteristic of the expanded anemone.
There are a number of other species of Sagartia, mostly
showing some indication of the elaborate patterns of S.
troglodytes, but these do not occur, between tide-marks at
least, on the East Coast, and naturalists living on the West
may be referred direct to Gosse's book.
The last of our East Coast species is Actinoloba dianthus,
the plumose anemone, a form which is often said to be an
inhabitant of deep water, but which in sheltered places is
not uncommon between tide-marks. On the Clyde it has a
special preference for the supports of piers, and there occurs
in the most gorgeous profusion, clustering thickly about the
whole length of the uprights; the smaller specimens between
tide-marks, the larger further down, so that their pale tints
gleam faintly through the green depths of water, and the
outlines of their translucent bodies are hardly discernible in
the dim light. In such situations they reach a great size,
having a column some six inches long, with a disc of several
inches in diameter. But it is only under exceptional cir-
cumstances that such specimens can be seen close inshore,
certainly not as a rule in the shallow waters which fringe
the beach on the East Coast. There one cannot look for
specimens of more than an inch or so in height, and as
already mentioned, these usually occur in sheltered places
SEA-ANEMONES AND THEIR ALLIES. 73
only. Often they are found under overhanging rocks or in
deep and dark rock crevices, but on the Firth of Forth, on
the other hand, I have found numerous specimens growing
fully exposed to view on loose stones on the shore. In this,
as in many other cases, we require more evidence before we
can determine what it is that renders a locality suited to the
Fia. 26. — The plumose anemone (Actinoldba dianthus). Note the "parapet "
or ridge, beneath the frilled disc. After Tugwell.
needs of the species ; it may be a protection against violent
wave-action which is necessary, or the abundance of some
particular kind of food, or a constant supply of pure water,
or some other unknown environmental condition. Certain
it is that this is a local anemone, abundant where it occurs,
but often absent from apparently suitable spots. It is also
very variable in colour, being sometimes white, sometimes
yellow, sometimes flesh-coloured. The fact that all three
colour varieties may occur in the same situation seems
74 LIFE BY THE SEASHORE.
against the supposition that the colour variations are
"adaptive," or directly determined by the environment.
As to the general characters of this anemone, notice the
smooth cylindrical column, with no trace of suckers, but
with minute pores, from which acontia may be emitted.
The upper margin of the column is thickened, and forms a
"parapet," which is separated from the frilled disc by a
groove or fosse. It is this frilled or puckered disc which is
so distinctive a character of the anemone. It is very thin,
and bears very numerous small tentacles, banded with white,
the whole appearing like the "foliated crown of a palm
tree." The mouth is grooved, usually has its margins highly
coloured, and has one, two, or three siphonoglyphes (see
p. 66) — a very interesting range of variation, which also
affects the mesenteries internally, and which you should not
fail to notice.
The plumose anemone lives well in captivity, and is
remarkably active for a sea-anemone, continually changing
its position, but generally keeping very close to the surface
of the water, where the oxygen must be most abundant.
Often in the course of its movements it leaves a fragment
of the wide base behind it, and this fragment may grow into
a new anemone. Both in captivity and in natural conditions
it has a curious habit of distending a part of the body with
water while the disc and tentacles are retracted, and then
drops in a limp and flaccid way from its point of attachment
— a translucent shapeless mass. In the young specimens
the tentacles are not so numerous, and the disc is not dis-
tinctly frilled, but even at this stage it is hardly possible to
confuse it with any other anemone.
Related to the sea-anemones are the Alcyonarians, which
are represented on the shore by Alcyonium digitatum, or
"dead men's fingers." It is a colonial form, consisting of a
number of small polypes embedded in a fleshy mass. After
death the fleshy substance is much more conspicuous than
the polypes, and in the condition in which it is tossed on
shore after storms is not a pleasing object, for there is no
beauty of form, and the colour is too " fleshy " to be pre-
possessing. In the living condition, on the other hand, with
its glassy polypes fully expanded in a quiet pool, it is a
singularly beautiful creature, and one very well worth study.
SEA-ANEMONES AND THEIR ALLIES. 75
Though perhaps not a strictly littoral form, in sheltered
situations large colonies may often be found between tide-
marks, usually in company with Actinoloba diantlms.
Probably in both cases shelter from violent wave-action is
indispensable, and it is only where this is attainable that
life in the littoral zone becomes possible for either. Small
colonies with a diameter of perhaps J inch to J inch are
often common in rock pools, but the full-grown colonies form
bulky lobed masses, several inches in height and diameter.
The fleshy substance (ccenosarc) is yellow or pinkish, but
the polypes themselves are clear and colourless. They each
bear eight tentacles, while sea-anemones have their tentacles
in multiples of six. Further, each tentacle is pinnate, or
fringed with small processes arranged like the barbs of a
feather, the result being to produce a beautiful star-like
crown when the tentacles are spread out in the water. The
internal anatomy generally resembles that of sea-anemones,
and some of its details may be made out through the
transparent body-wall. Each polype is placed in a small
cavity of the pulp or ccenosarc, into which it may be
retracted. The coenosarc contains a series of canals, which
place the polypes in communication with one another, and
is strengthened by limy spicules scattered through its
substance.
Eelated to Alcyonium is the very beautiful sea-pen (Pen-
natula phospJiorea), which occurs freely in deep water, and
may sometimes be obtained from the fishing-boats. It is in
the form of a fleshy plume of red colour, the upper region
bearing numerous polypes like those of Alcyonium. It has
a central rod of lime in its lower region, and so leads up to
the red coral of commerce, which is in reality the supporting
axis of a fleshy coenosarc bearing numerous polypes like
those of Alcyonium. It thus differs markedly from the
majority of the " corals " which are made by the aggregation
of many limy cups containing polypes ; that is, are built on
the same plan as the horny skeleton of a Campanularian.
In the red coral there are no cups, for the polypes are placed
in a fleshy ccenosarc, as in Alcyonium^ this being removed
during the process of preparation of the coral. It may
perhaps be well at this point to spare a few words to repeat
that "corals" are the hard parts of Ccelentera, and there-
76 LIFE BY THE SEASHORE.
fore have nothing whatever to do with Insects, so that that
artless little metaphor about the devotion to duty exhibited
by the "coral insect," which has rooted itself so deeply in
the mind of the popular orator, is sheer nonsense — a not
uncommon characteristic of oratorical "scientific analogies."
We have already mentioned the fact that the big "jelly-
fish," as distinct from the delicate swimming-bells, appear
to be related to the sea-anemones and Alcyonarians rather
than to the Hydrozoa. Of these jelly-fish only some three
or four are common round our coasts, but these often occur
in such countless numbers that they are more or less
familiar to everyone. We shall only describe one of these
in detail, choosing it because certain stages in its life-
history are to be found on the shore rocks. This is Aurelia
aurita, easily recognised by four horseshoe-shaped purple
bands seen on its dorsal surface, and recommended by the
fact that it can be handled without danger of being stung,
so far, at least, as my experience goes. Let us begin with
the larva, which is certainly minute and harmless enough.
It is a little creature called a hydra-tuba, is pure white, and
is to be found attached to rocks by one end of its body,
while the other is furnished with a mouth surrounded by
waving tentacles. It is, you may say, merely a polype of
a type with which you are now quite familiar. This is
indeed the case, but it has been shown that, small and
simple as it appears, the hydra-tuba in certain points
suggests connection with the sea-anemones and not with
the Hydrozoa. It is usually not more than one-eighth of
an inch in height, and is to be found far out on the rocks.
In late summer it undergoes certain changes presently to
be described, but, oddly enough, these changes may some-
times be arrested for an apparently indefinite period. I
have seen captive specimens which the owner assured me
had been kept for several years without showing any signs
of change. Under natural conditions, however, the little
hydra-tuba elongates and becomes marked by a series of
transverse lines, so that it appears like a pile of saucers.
A little later the top "saucer" floats off, turns over, and
becomes a little jelly-fish which grows rapidly and becomes
an Aurelia. The same thing occurs with the lower
"saucers" of the pile, so that the tiny hydra-tuba gives
SEA-ANEMONES AND THEIR ALLIES. 77
rise to a number of large jelly-fish. There seems almost
no limit to the size a jelly-fish may reach, but specimens
of Aurelia aurita round our coasts commonly vary from
six inches to a foot or more in diameter. If this be com-
pared with the minute size of the hydra-tuba, and the
relative sizes of the sea-firs and their swimming-bells be
recalled, it will be clear what is meant by the statement on
page 64 that in the alternations of generations seen in the
jelly-fish, the free-swimming stage is accentuated at the
expense of the sedentary stage.
To get a general idea of the structure of a jelly-fish, some
specimens of Aurelia aurita should be obtained. They are
usually very abundant in August, and care should be taken
to obtain one or two living specimens not too large to be
readily observed. The living animal is much more attractive
than the flattened, half-melted creature so often left on the
beach by the ebbing tide. In it the umbrella is sharply
curved, not flat as in dead or relaxed specimens, and its
slightly inturned margin is furnished with numerous slender
tentacles of perhaps a couple of inches in length; after
death these are always much contracted and become incon-
spicuous. The manubrium, or clapper of the bell, is divided
into four somewhat short arms, having the mouth opening
in the centre. You should not fail to notice that in some
others of our jelly-fish (Oyanea, Chrysaora) the tentacles
are very long, and so are also the frilled and puckered arms
of the manubrium. As to the other characters of Aurelia^
the four horseshoe -shaped reproductive organs are very
obvious, and by turning the animal over you see that
beneath each of these is a little pit, opening to the exterior
by quite a distinct orifice. These are often called "respira-
tory" or genital pits, but are believed by some authorities
to be remnants of larval structures. There is no "veil"
like that of the swimming-bells, but the jelly is traversed
as in them by a series of radial canals, in this case rendered
very obvious by their violet tint. At the margin of the
bell there are eight sense-organs, or " tentaculocysts," which
are easily made out.
Related to Aurelia there are, as already mentioned, some
other jelly-fish, often of large size, and sometimes with very
distinct stinging power. The very large forms are more
78
LIFE BY THE SEASHORE.
likely to be found on the West than on the East Coast,
and in any case are somewhat beyond our scope. There is a
small, delicate creature, however, to be found on the rocks
which is related to the jelly-fish, though it differs from
them markedly in appearance. This is Lucenaria, or as it
is now called, Halidystus odoradiatus. It is, perhaps,
rather umbrella -shaped
than bell -shaped, but
there is nothing to re-
present the stick of the
umbrella — that is, no
manubrium — and the
region of the body oppo-
site the mouth is pro-
longed into a short stalk
which is attached to
weed in the pools. The
free margin of the um-
brella bears eight groups
of short tentacles, and
the mouth has the usual
central position. It is
an animal which is diffi-
cult to find, though perhaps it is not very uncommon, and
reaches a size of one inch or so. The difficulty is largely
due to its delicacy and transparency, and to the fact that
in colour it usually resembles the weed to which it is
attached. It shows no trace of alternation of generations,
and is interesting on account of a certain general resem-
blance to a hydra-tuba, so that one might suppose that it
was a larval jelly-fish which had forgotten to grow up, and
had become adapted for a sedentary life. It is not a
perfectly stationary form, but possesses some power of
moving about, and by attaching itself, first by the stalk
and then by little marginal tubercles which alternate with
the tentacles, can progress like a "looping caterpillar." It
is a charming little creature, but, so far as my experience
goes, not easy to keep in confinement. The colour is very
variable, being brown, green, or claret-coloured, according
to the colour of the surrounding weed. The accompanying
figure should make the structure obvious.
Fia. 27.— Halidystus octoradiatus.
SEA-ANEMONES AND THEIR ALLIES. 79
The third and last class of the Coelentera includes a few
beautiful free-living forms to be found floating at the surface
of the sea. They may occasionally occur in the rock pools,
but are more likely to be found in the open water, where
they may be seen as little iridescent bells floating past the
boat, in company with the tiny swimming-bells and the giant
jelly-fish. These iridescent globes of jelly are members of
the class CTENOPHORA, and differ markedly both from the
true jelly-fish and from the swimming-bells. Two genera
are not uncommon, Beroe and Pleurobrachia (see Fig. 93),
sometimes called "iridescent fire-globes," or "sea-gooseberries."
In the former the body is oval in shape with a wide mouth
occupying the whole of the under surface, in the latter it is
somewhat pear-shaped with a small mouth. When removed
from the water both are colourless and delicately transparent,
but when seen in active movement in the water both gleam
with rainbow tints. This is due to the fact that the long
axis of the body, from pole to pole, is traversed by eight
bands of motile plates (four of these are shown in the figure),
which in life are in constant movement, and propel the
animal through the water, while by breaking up the light
they also produce the changing play of colour. The structure
of the body in both JSeroe and Pleurobrachia is a little
complicated, so we need only notice further that the latter,
but not the former, has two very long delicate tentacles
which can be instantly retracted, or allowed to stream out
like a long train behind the body (see Fig. 93). Both are
most delicately beautiful animals in life, and should be
looked for every summer, if only for the sake of their play
of colours and graceful movements. As in the jelly-fish,
most of the charm is lost after death.
Perhaps it may be thought that in this and the preceding
chapter we have eulogised ad nauseam the delicate beauty
of a group of animals known to most people chiefly as
"nasty stinging jelly-fish," but it is difficult to tear one's self
away from a group whose members are adapted for so many
different kinds of surroundings, and yet are essentially so
simple and so uniform in structure. Their fascination, too,
is enhanced by association, for many of them are "fair-
weather animals," and all must be studied in the open air
for their beauty to be fully appreciated. To anyone who
80 LIFE BY THE SEASHOEE.
knows them well, the very thought of Beroe, or medusoid,
brings back a vivid recollection of summer days spent idly
drifting over sunlit seas, when every rippling wave displays
new shapes of beauty, new gleams of rainbow colour. The
zoophytes similarly recall hours spent at the side of clear
rock pools, yielding every moment new charms to patient
search, new combinations of colour to the educated eye.
Even those to whom animals as a rule appeal but little
may be recommended to examine these sea-flowers, which
are to be found in every pool, and may be studied there in
all their beauty, without apparatus and without interference.
They are also especially suited to those who shrink from
comparative anatomy, as a rule, because it involves the
death of the object studied, for most of the Ccelentera can
only be properly investigated in the living condition, and
will yield many of their secrets to the unaided eye of a
patient observer.
We have added to this chapter a table which may not
only assist in the naming of specimens, but also in enabling
the student to appreciate the number of different kinds of
animals included in the group Coelentera.
CCELENTERA— continued from p. 61.
Class II. — SCYPHOZOA.
Sub-class I. — ANTHOZOA. Sedentary polypoid forms, simple or
colonial.
Order I.— ZOANTHARIA. Tentacles simple, in multiples of six,
sea- anemones.
[ Tentacles slender. i „ . .
Acontia present. \ Sa9art™'
Column with suckers . -<
Tentacles very thick. \ ». ,.„
No acontia. Tealm'
Column quite smooth
Tentacles very small
and numerous, disc
plumose. Acontia pre-
sent.
Tentaclesnotverysmall, -\
with blue beads at their V Actinia.
base. No acontia. J
Order II. — ALCYONARIA Tentacles feathered, in multiples of eight,
all colonial.
Coenosarc lobed, with scattered spicules . . Alcyonium.
Ccenosarc pen-shaped, with a central axis . . Pennatula.
SEA-ANEMONES AND THEIR ALLIES. 81
Sub-class II. — SCYPHOMEDUS.E. Jelly-fish with subgenital pits and
no velum or veil.
Order I. — DISCOMEDUSJE. Active forms with complicated life-history.
Four horseshoe-shaped genital organs . . . Aurelia.
Order II. — LTJCENARIJE. Sessile forms . . Ealidystus.
Class III.— CTENOPHORA. Free living forms with eight rows of
plates.
Two tentacles and small mouth . . . Pleurobrachia.
No tentacles and wide mouth . . Beroe.
SUMMARY CLASSIFICATION OF CCELENTERA, OR SEA-NETTLES.
Class I.— HYDROZOA (Chap. II.).
(a) Gymnoblastea, polypes without
protective sheath, e.g. Clava and
^ -, TT -, j other common zoophytes.
A. Order Hydromedus* • j(i) Calyptoblastea, polypes placed in
cups, e.g. Obelia and other com-
mon sea-firs.
B. Order Siphonophora .
Class II.— SCYPHOZOA (Chap. III.).
A. Sub-class ANTHOZOA.
1. Order Zoantharia — sea-anemones and corals.
2. Order Alcyonaria — "dead men's fingers," sea-pens, etc.
B. Sub-class SCYPHOMEDUS^:.
Various orders, including the large jelly-fish and Haliclystus.
Class III.— CTENOPHORA. Free-swimming forms like the "sea-
gooseberries" (Beroe), etc.
NOTE ON DISTRIBUTION.
The sea-anemones described in this chapter have been those of the
East Coast, which is poorer in species than any other part of our area.
It is not possible to name all the common anemones of the South and
West, but a few notes may be given. In most places on the West the
beautiful Anthea cereus, an anemone with smooth column and non-
retractile tentacles which occurs in a brown and a green variety, is
common. It is especially common on the coasts of Devon ; north
of Devonshire, so far as my experience goes, the brown variety is
commoner than the green, which is much the handsomer. Again,
while at Alnmouth, St. Andrews, and on the shores of the Firth of
Forth, Sagartia troglodytes is excessively common, it is probably less
common on the South and West — is certainly rendered less con-
spicuous by the occurrence of many other somewhat similar species.
At Mill port, for instance, Sagartia miniata, which has the outermost
row of tentacles with a scarlet core, is one of the commonest anemones
of the pools. Another species, Sagartia bellis, or the daisy anemone,
is very common on the coasts of Devon and Cornwall.
G
CHAPTEE V.
THE BEISTLE-WOKMS.
Different kinds of worms — Nematodes — Polychaetes — External appear-
ance of Nereis — Structure of the fisherman's lob-worm — Habits
of worms — Common shore worms — The scale-worms, or Polynoids
— The leaf-worms, or Phyllodocids.
fT^HE group of " worms " is an exceedingly large one, and
_L includes a great number of forms not closely related to
one another. Many of these are, however, small or rare,
and need not trouble us here, so that we shall consider in
detail two sets only — the ribbon-worms (Nemertea) and the
bristle-worms (Chaetopoda). Two other sets — the round-
worms (Nematoda) and the sea-mats (Polyzoa) are almost
certain to be also encountered on the shore, and should be
briefly referred to. The Polyzoa will be discussed after
we have studied some more representative forms, but the
Nematodes may be dismissed in a few words.
In turning over stones on the shore, in search of nobler
prey, one not infrequently comes across little white or
almost transparent worms, which move with an active
wriggling motion, and are rounded in cross section. They
are especially abundant in pools containing decaying organic
matter or odoriferous mud. These are round worms, or
Nematodes, harmless enough in this case, but nearly related
to some of the most dangerous parasites of man. Almost
always of this dead white tint, there is s- mething in their
very appearance which suggests their degraded and repulsive
mode of life. In spite, therefore, of the fact that they
exhibit many points of zoological interest, we may allow
our instincts to guide us in passing them by, especially as
their small size unfits them for our purposes. As these
82
THE BEISTLE-WORMS. O6
purposes are the acquisition of a practical knowledge of the
structure of worms, we shall begin with the bristle-worms,
or Chsetopoda. They are more highly differentiated than
the ribbon-worms, are often of considerable size, and are
easy to examine and dissect.
The Chsetopoda (or " bristle-feet ") include two main sets of
worms — the marine forms (the Polychaetes), worms usually
with many bristles, arranged on lateral outgrowths of the
body (the parapodia or feet), and the Oligochsetes, worms
like the common earthworm, living in earth or in fresh
water, and having only few bristles. It is the marine
worms only with which we are concerned here.
The first step is, of course, to find the worms, but this is
considerably easier than in the case of the historic hare.
There is no shore so barren and desolate that it does not at
some point or other show traces of the bristle-worms. On
the mud-flats at the mouths of the rivers, on the smooth
sandy shore at the edges of the rocks, or in the sandy bays
in the middle of the rocks, one finds in abundance the
"castings" of the common lob-worm. The dark seaweed
thrown up by the breakers nearly always bears upon its
fronds the little coiled dead-white tubes formed by the tiny
Spirorbis. Among the debris which accumulates at tide-
mark, a careful scrutiny will almost always reveal the neatly
made tubes of Terebella decorated with particles of shell
and stone, and encircled at the tip by a fringe of stiff sandy
threads. The shore rocks are often in places covered with
masses of the sandy tubes of Sabellaria, which look them-
selves like an outcrop of porous rock. We might, indeed,
continue the list almost indefinitely, but let us first choose a
typical form for closer study.
In turning over stones on the rocks between tide-marks,
especially in slightly muddy pools, you are almost certain
sooner or later to dislodge the worm for which we are
seeking (see Fig. 28). When disturbed by the removal of
the stone under which it has been lurking in an ill-defined
burrow, it swims away with a peculiar wriggling motion. The
colour is brown or greenish, and there is usually a faint but
distinct metallic sheen. The length may be as much as six
inches, but in forms from shallow water it is likely to be
considerably less. The upper surface is arched, the lower
84
LIFE BY THE SEASHORE.
flat with a distinct median groove, and the worm is uniform
throughout its length, tapering towards the posterior end.
It is very distinctly ringed, each ring bearing a pair of
small lateral outgrowths, or parapodia,
which carry bristles. A worm exhibiting
these characters is pretty sure to be a
species of Nereis, and most probably N.
pelagica. Catch one or two of the largest
you can find, and place them in a bottle
with seaweed and clean water. They are
not easy to keep in confinement, and will
probably not live longer than a day or
two, but this is long enough to observe
some of the habits, the method of swim-
ming, and so forth. If it is not desired to
keep them alive, they may be killed at
once by dropping direct into methylated
spirit or formalin.
After death, whether this be due to
natural causes or to artificial means, you
may proceed to your examination. This is
most easily done by making at once a
drawing of the animal, a practice which
should be the invariable rule. The very
act necessitates far closer observation than
is likely otherwise to be given; the relative
slowness of the process impresses the facts
firmly upon the memory; the drawing,
however rough, forms afterwards a most
FIG. 28.— Nereis peia- valuable record of the work done ; and
OT^rostomiui^witti fiIiaUv> in accordance with a familiar
its small feelers and psychological rule, the concentration of
peSmiumblfnd attention necessary to produce an ac-
it with four pairs of curate drawing will intensify a thousand-
cirri, but no feet. » , , , , , ° , , . % .
told the pleasure obtained irom your
dissection.
As to the details of the process, my own experience is
that an artist's sketching -block of small size, where the
sheets can be torn off as they are used, is more convenient
than a book. The sheets can be kept in a portfolio and
arranged in order there, whereas in a book it is virtually
THE BRISTLE-WOKMS. 85
impossible to maintain a proper sequence. A water-colour
sketch, the parts being as nearly as possible the colours of
life, is the form of sketch most likely to produce permanent
satisfaction, but where this is impossible a mapping-pen and
Indian ink should be used in preference to pencil; pencil
drawings on loose sheets being very apt to get blurred.
Annotate your drawings fully at the time that they are
made, and mark carefully those points about which you are
uncertain; in time light will probably dawn. In addition
to the careful drawings of the whole animal, a few entirely
diagrammatic sketches of the separate parts should be
made.
As to the points disclosed by your examination, a Nereis
is a ringed worm (Annelid), composed of a series of rings or
segments, each of which is of similar structure. You may
compare it roughly to a railway train, composed of numerous
similar carriages linked together. Consider for a moment
the railway train as the more familiar object. Its form is
obviously an adaptation, as the biologist calls it, to its
particular form of movement. As it sweeps gracefully
round a curve, you see at once how necessary and suitable
its form is, how much the freedom of movement depends
upon the yielding linkage. Almost all animals which can
move rapidly and gracefully in water, and are of elongated
shape, are similarly composed of a series of units. In the
language of Biology they are segmented animals, and Nereis
and its allies illustrate one of the simplest forms of seg-
mentation. A simple form because the component units
are similar throughout the body, only the anterior and
posterior ends showing slight structural differences. With
Nereis should be compared, on the one hand, the Nematodes,
with their unsegmented bodies and peculiarly stiff method
of locomotion, and, on the other, the more differentiated,
segmented animals, such as crab and crayfish, where the
body-units are no longer all similar, but are adapted to serve
different functions.
Let us now examine the segments in detail. Any of
those from the median part of the body, taken at random,
will show the following points : first, the characteristic
shape, rounded above and flattened beneath with a central
groove ; then the appendages, large lateral outgrowths, form-
86 LIFE BY THE SEASHORE.
ing the parapodia, or "feet." Of these each segment bears
a pair, and their structure is somewhat complicated (see Fig.
29). Each consists of a dorsal
and ventral process, both bear-
ing tufts of stiff bristles. More
careful examination by means
of a lens will show in addition
the following points. Both
dorsal and ventral processes
t, or parapodium, of are Globed, and it is the lower
Nereis pelagica. d, dorsal cirrus ; lobe of the dorsal and the Upper
WiS»\WS*S: ^be of the ventral only which
relative lengths of the d.fferent bear bristles, the other two
parts, and especially the long , , IT,
dorsal cirrus, are distinguishing lobes are mere vascular plates.
Ehters. °f the Spedes' After Further, both processes give off
slender sensitive outgrowths,
the feelers, or cirri, of which one is dorsal and the other
ventral. The bristles have usually a peculiar golden sheen,
and in each tuft there is one of needle-like shape which
only projects very slightly, but which is easily found on
dissection. It is to these needles that the muscles are
attached, and they form, as it were, the skeleton of the foot.
To recapitulate, the parapodia are hollow, muscular out-
growths of the lateral body- wall; they are divided into
bilobed dorsal and ventral processes, each bearing bristles,
each giving off a delicate sensitive cirrus. By virtue of
their muscles and bristles the parapodia are locomotor
organs ; by virtue of their contained blood-vessels they are
respiratory organs; by virtue of their sensitive cirri they
are sense-organs. As one or other of these three functions
predominates in the bristle-worms, we have a corresponding
variation in the structure of the foot.
If we look now at the anterior region or head, we find
that it differs considerably from the other parts of the body.
Overhanging the mouth is a dorsal lobe which bears eyes
and tactile processes, and is the head proper. The lobe is
called the prostomium, and is probably not equivalent to
a segment. Surrounding the mouth is the peristomium, or
first true segment, which also bears tactile processes, but
has no parapodia nor bristles. In most bristle-worms the
head region consists of these two parts, but in a few, other
THE BRISTLE-WORMS.
87
Fig. 30).
modified segments are added to it. This is interesting, because
when we pass to Arthropods we shall find that the head con-
sists of a number of segments all firmly welded together.
The head of Nereis varies considerably in appearance,
according to the condition of the parts, whether fully pro-
truded or retracted. If a large Nereis be killed suddenly,
as by immersion in spirits, it will be observed to rapidly
protrude a large "proboscis" or "introvert," which when
completely everted shows at its tip a pair of powerful horny
jaws (see Fig. 30). The method of eversion is interesting,
and is one which is common among Invertebrates. It is
best understood by taking a glove, fastening two pieces of
thread about an inch from the tip of one of the fingers
to represent the jaws, and then doubling in the finger into
the glove as far as it will go (see the upper diagram in
The hole left where the finger is doubled in
represents the mouth of the
worm, and it will be seen that
the little tags representing the
jaws (j in Fig. 30) now lie well
within the mouth-cavity (m in
Fig. 30) ; they are not visible
in the worm under ordinary
conditions. Now carefully
double the inturned glove finger
outwards until the "jaws" lie
just at the tip of the part
turned out; this represents the
"proboscis" of Nereis when
fully everted, and then bearing
the jaws at its tip. All the
part which can be thus everted
is called the buccal cavity. It
opens into the pharynx (p in
Fig. 30), the next part of the alimentary canal, which is
represented by the remainder of the glove finger, but
which differs from it inasmuch as it cannot be everted, or
turned outwards, but can merely be protruded with its
terminal jaws. The head, therefore, of Nereis appears
entirely different according to whether the buccal region is
retracted or everted. In the former condition the mouth
FIG. 30. — Diagrams showing the
way in which the proboscis is
everted and retracted in Nereis,
The upper figure (^4) shows the
retracted condition, the lower
(Z>) the everted. For letters see
text. After Lang.
88 LIFE BY THE SEASHORE.
appears as a wide opening beneath an overhanging lobe,
and some little distance from the anterior end of the body.
In the second condition it appears at the end of the everted
proboscis, bounded by the great jaws, and opening directly
into the protruded pharynx, the proboscis itself being
merely the anterior part of the alimentary canal in an
everted condition. The actual appearance of the everted
proboscis with its small teeth is shown in Fig. 35.
We may now pass on to consider the appearance of the
head proper. In the living animal, or in the dead animal
with retracted proboscis, the mouth is seen to be ventral
and overhung by the prostomium. On its dorsal surface
the prostomium bears two pairs of eyes, and in addition
a pair of very small tentacles and a pair of distinct large
processes called the palps (see Fig. 28). The next ring,
the peristomium, bears, as we have seen, no parapodia, but
only four pairs of long feelers or tentacular cirri, which are
used like the feelers of an insect.
Behind this head region the segments are all uniform and
similar except the last, which is without parapodia, but
bears a single pair of long tactile cirri, or feelers.
Having made out these points in the external anatomy of
a typical Chaetopod like Nereis, the next point is to get
some notion of the internal anatomy. This may be done
by proceeding at once to dissect Nereis; but unless some
experience has already been acquired, it will probably be
found easier to begin with the fisherman's lob- worm (Arenicola
piscatorum), which can readily be obtained of large size,
and which is exceedingly easy to dissect.
The lob-worm is abundant on most sandy shores, especially
in sand which contains a considerable amount of organic
matter. It is a sedentary worm, burrowing in the sand,
and lining the burrow with an organic secretion, which
gives the walls a certain amount of firmness and renders
them easily visible when the sand is turned up. It swallows
the sand for the sake of its organic particles, and rejects
the indigestible residue in the form of the familiar sandy
"castings." If these be pushed away the mouth of the
burrow can be seen, and the burrow itself may be followed
some distance by digging in the sand.
For the purpose of examination and dissection the lob-
THE BRISTLE-WORMS. Q\)
worm may be obtained by digging in the sand where the
castings are abundant. Except by the intervention of a
strong arm and a powerful spade, however, the process is
not very easy, and the simplest plan is usually to invoke
the aid of a fisherman — amateur or professional. The speci-
mens chosen should be not less than seven or eight inches
in length, and should be obtained uninjured and in the
living condition. The worms have an exceedingly well-
developed blood-system, and are full of blood, a fact which,
combined with the delicate body-wall, makes it not very
easy to obtain perfectly uninjured specimens.
The lob-worm will not be found easy to keep alive for
any length of time, but it will live for a day or two if
placed in a vessel with wet sand, and there some of its
habits can be readily observed. The way in which it moves
is especially interesting, but before describing this we must
just glance at its external characters (see Fig. 10).
In studying these we are at once struck by the marked
contrast with Nereis, especially in the condition of the
parapodia. Let us recall for a mome*nt the functions of
these structures in Nereis; they are locomotor, respiratory,
sensitive. Now the lob-worm is more or less sedentary, so
that we should expect that the parapodia, in so far as they
are locomotor organs, will show reduction. Correlated with
the sedentary habit we have here, as always, a greater
difficulty in breathing, and so we have the development of
special respiratory organs, the gills. Again, a sedentary
animal has a more limited environment than an active one,
and is less likely to have well-developed sense-organs, so
that we should expect to find that the parapodia have to a
large extent lost their sensitive nature. The first glance at
Arenicola will show that with loss of function there is also
degeneration of structure. Its parapodia are mere rudiments,
little tufts of bristles. The characteristic sensitive cirri of
Nereis seem to be absent, we say seem to be advisedly, for
the tuft-like gills in the middle region of the body are in
reality the metamorphosed dorsal cirri, which have lost their
sensitive and taken on a respiratory function. With the
exception of these gills, in reality a specialised portion of
the parapodia, the parapodia of Arenicola are very greatly
reduced, and do not function as locomotor organs.
90 LIFE BY THE SEASHORE.
Having noticed these points, study the movements of the
living worm. The body is divided into three regions — an
anterior, usually much swollen, region, with lateral tufts of
bristles; a median region, with the conspicuous gills and
less obvious bristles ; and a tail region, with neither bristles
nor gills. As it is thus destitute of definite locomotor
organs, our first query must be, How does Arenicola move 1
If you watch your specimens closely, you will be struck by
a marked and peculiar wave of motion which begins in the
gill region, and gradually sweeps forward to the anterior
end. This wave produces a very marked distension of the
body, and has all the appearance of being due to the passage
forward of fluid within the body-cavity. The distension is
most marked in the anterior region, and often terminates in
the protrusion at the extreme anterior end of a " proboscis,"
with numerous papilla on its surface, which is obviously
homologous with the "introvert" of Nereis. As the wave
sweeps forward it will be noticed that the little tufts of
bristles are completely withdrawn into the body, which
must greatly diminish the resistance to the passage through
the sand. As the wave passes any particular spot, it will be
further observed that, immediately after its passage, the
bristles are protruded to their fullest extent. When the
worm is lying on a smooth surface the forward wave is
followed by a backward one, during the course of which the
animal slips slightly backwards. There can be little doubt,
however, that under ordinary conditions the protrusion of
the bristles must prevent this, for they will tend to grip the
sides of the burrow. The lob-worm thus works its way
through the sand as the earthworm does through the earth,
and in both cases the bristles are of great importance. The
process is a very interesting one, and can be readily watched
in a living Arenicola lying on wet sand.
The lob-worm, indeed, is of interest in several respects,
for it seems to stand half way between the active worms
like Nereis, and the very passive tube-forming types like
Terebella and Serpula. At one time the PolychaBtes were
divided into two sets — the sedentary tube-builders, and the
active free-living forms. This classification is no longer in
use, for it is found that many forms not nearly related have
independently taken to a sedentary life. Nevertheless, it
THE BRISTLE-WORMS. 91
had a superficial justification in the fact that sedentary
forms have certain external characters in common. In
Arenicola we see, as it were, the first effects of the passive
life upon the organism. As the sedentary habit becomes
more firmly fixed, the bristles become more degenerate,
except when specialised anteriorly to aid in tube-building.
At the same time the tube becomes more and more highly
developed. It may consist entirely of secretion poured out
by the animal, or may be composed of foreign particles glued
together by the secretion. This secretion is present to a
slight extent in Arenicola^ where, as we have seen, it gives
a certain amount of firmness to the walls of the burrow.
In most tube-builders there are on the ventral surface
swollen areas, known as "gland-shields," which seem to be
of much importance in tube-formation. Though these as
such are not distinct in Arenicola, yet the ventral surfaces
of the segment lines in the middle region of the body are
in life much swollen, and are probably of much importance
in the production of the secretion used in lining the burrow.
In looking for these glandular regions it will be noticed
that in Arenicola the body is closely ringed, the rings being
more numerous than the bristles which mark the segments.
Having observed these points, the next step is to dissect
the internal organs. Pin the animal down on wood or
paraffin under water, with the dorsal surface — that bearing
the gills — uppermost. An ordinary pie-dish, in which a piece
of weighted cork or wood has been placed, makes an excellent
dissecting-dish, or a couple of candles may be melted in the
pie-dish, and the animal pinned down on the solidified
surface. Put the anterior pin in carefully, so as not to
injure any of the internal structures. Then take a pair of
fine scissors, and slit up the dorsal surface between the gills
from the head to a little behind the last gill. Pin out the
body-walls, and the dissection should present the appearance
shown in the figure.
The first point to be noticed is the large size of the body-
cavity, and the absence of transverse partitions, or septa.
The large body-cavity is characteristic of bristle-worms in
general, but in most of them it is divided into numerous
compartments by divisions which correspond to the segments.
The absence of these septa is no doubt an adaptation to the
92
LIFE BY THE SEASHORE.
burrowing habit, for it enables the body fluid to move freely,
and, as we have seen, that has an important bearing in
relation to the method of movement. The absence of septa
is further correlated with
the power of distending the
anterior part of the body,
which has an important me-
chanical effect in burrowing.
Running down the centre
of the body is the alimentary
canal (al in Fig. 31), which
in most bristle - worms per-
forates the septa, but which
is here almost free in the
body- cavity. Not entirely,
however, for in the anterior
region there are three sup-
porting mesenteries (s'} s",
s'"), and behind the gill-
bearing region there are many
of these. The anterior mesen-
tery, or diaphragm, is a struc-
ture of great interest. It is
completely circular, and is
attached to the alimentary
canal at the point where the
protrusible region, or buccal
cavity, opens into the next
region. During the burrow-
ing movements the body fluid
sweeps forward until it is
stopped anteriorly by this
circular diaphragm. It then
exerts a pressure upon the
diaphragm to which the latter
can yield in one way only —
by the protrusion of the in-
trovert, which is doubled
FIG. 31. -Dissection of lob-worm from dor- outwards by the pressure of
sal surface. For explanation, see text, the fluid behind. When the
In part after Gamble and Ash worth. ,
wave sweeps backwards again
al
THE BRISTLE-WORMS. 93
the introvert is retracted, but carries with it a certain amount
of sand, which, be it remembered, contains the animal's food.
The process of burrowing is thus aided by the removal of part
of the sand, while the power of distending the body, espe-
cially in the anterior region, facilitates the progress of the
animal. This power is associated with the absence of septa,
and we thus see how deeply habit affects structure, and
therefore how it is that the sedentary forms show such an
apparently close relation to one another. It is one of the
most difficult tasks of philosophical zoology to distinguish
between resemblances in animals which are due merely to
adaptation to a similar mode of life and those which are due
to common descent.
As to the other structural peculiarities of Arenicola,
notice the large glands (gl) opening into the intestine, the
abundant blood-supply to the gills, the ventral nerve-cord
(n), seen by pushing aside the alimentary canal, and the six
pairs of kidney tubules, or nephridia (ne), in the anterior
segments, which open from the body-cavity to the exterior.
Into the minute points of structure we cannot enter here,
but may briefly summarise the salient features of the in-
ternal anatomy of a Polychsete worm. All have "a large
body-cavity, or space between alimentary canal and body-
wall, and this is usually divided into chambers by cross
partitions. The alimentary canal runs straight down the
body, and has anterior and posterior openings (contrast sea-
anemones and their allies). There is a ventral nerve-cord,
and typically a pair of kidney tubes to each segment, but
these are often reduced in number.
In classifying worms the most important points to be
noticed are the shape of the head and the nature of the
feet, or parapodia, and the bristles. Our British Polychsetes
are very numerous, so that we can select only a certain
number. Those selected are those which are fairly common
at most parts of our coasts, and are of sufficient size to be
examined and identified with a lens or simple microscope.
The more minute forms, though often of great interest, are
beyond our scope. Even with this limitation, however,
the worms form a difficult group, and their recognition can
never be made easy ; but their diversity of habitat renders
them a group of extraordinary interest. Many of them are
94 LIFE BY THE SEASHORE.
exceedingly beautiful both in form and colour, and the
habits of the tube-builders make them very interesting pets.
Although all are furnished with bristles, which are often
large and strong, yet most are greatly relished as food by
the carnivorous inhabitants of the ocean. This fact every
fisherman knows, and the voracity with which many fish
will take a worm bait explains clearly enough why it is
that the worms should display so much ingenuity in seeking
shelter. Often this shelter is of their own making, as
witness the great variety of tubes, from the simple jelly
envelope of Siphonostoma to the elegant sand tubes of
Pectinaria, and the limy coils of Serpula. Other worms,
like Nereis itself, form irregular burrows of sand and weed ;
or seek shelter in rock crevices, roots of weed, and empty
shells ; or bury themselves deeply in mud and sand. One
species of Nereis lives inside shells inhabited by the large
hermit-crab, and thus probably gets not only shelter but
scraps of its host's food. In what respect the hermit is the
gainer is less clear. Some other forms live among the
prickly spines of sea-urchins and starfishes, in this way no
doubt obtaining protection from soft -skinned foes. So
varied are the habitats of the worms that to the question,
Where should one look for them1? the answer may be,
Almost anywhere. In sand and mud, under stones and
overhanging rocks, among seaweed, wherever shelter and
food are to be obtained, the worms may be found. At the
end of this and the following chapters will be found tables
designed to aid the beginner in naming the common shore
worms, but many are not easy to identify.
The first example is one which is, practically speaking,
common everywhere on the shore. On lifting up stones
on the shore rocks you are certain sooner or later to uncover
a little creature about one to two inches in length, which in
general appearance is very like a " slater," but which when
disturbed wriggles away with a lateral movement of the
body which is quite characteristic. It is not very worm-
like in appearance, for the rings of the body are covered
by flat plates, or elytra, but the bristles which project at the
sides of the body quite clearly indicate its real nature. An
animal displaying these characters is tolerably certain to be
a species of Polynoe, and the commonest species on the
THE BRISTLE-WORMS. 95
shore is generally Pulynoe imbricata, the common scale-
worm. If you drop your specimen into a collecting jar you
will notice that it wriggles its way downwards through the
water, after a fashion which can hardly be justly described
as swimming. If you go on with your collecting and re-
examine the worm after an interval, you will probably find
that the jar contains, in addition to the worm, a number of
small flat plates of greyish tint. These are the elytra, or
scales, of the worm, and it not infrequently happens that
the little creature will throw off every one of these within
a very short period of its capture. When these are gone
the segmentation of the body is very clearly visible, and
the animal looks so different that it may not be recognised
as the same creature. Not a few of the shore animals have
this power of throwing off parts of their body, apparently
on very slight provocation, and in cases like the present the
use of the habit is not very obvious.
The Polynoids do not make satisfactory inhabitants of an
aquarium, nor do they generally make good preparations,
for it is very difficult to get a complete specimen. Never-
theless, a few specimens should be taken, for the animal
well repays examination. It is a very abundant and widely
distributed species, occurring on both sides of the Atlantic
and in Japan. It must, therefore, be very well adapted to
the conditions of shore life, though it is not easy to point
out the nature of the adaptations.
The following general points should be made out. The
body is short, flattened, and has nearly parallel sides.
The head has three tentacles and a pair of palps, while
the next segment, the peristomium, bears a pair of elongated
cirri at each side. The remaining segments are furnished
with parapodia of typical form, with dorsal and ventral
branches bearing bristles. Now it will be recollected that
in Nereis the parapodia bear dorsal and ventral tactile
processes or cirri. What about the cirri of Polynoe? A
little careful examination will show you that the ventral
cirri are present on all segments, though except in the case
of the anterior segments they are short. The dorsal cirri
occur in the typical condition on every second segment in
the anterior segments, and in the posterior region are missing
only from every third segment. When they are absent
96 LIFE BY THE SEASHORE.
elytra, or scales, are present, and these elytra are un-
doubtedly nothing but metamorphosed dorsal cirri. We
thus see that though Polynoe has so little apparent resem-
blance to a " worm," yet it is in all essentials of structure
similar to Nereis. It is a great part of the interest of
worms that they show in this way how structures may be
modified and metamorphosed to fulfil different functions,
and satisfy changed needs. The elytra are hardened, horny
structures, and must serve to protect the organism, while
they are said also to be sensitive like the unmodified cirri.
We shall not consider the structure of Polynoe in further
detail, but may just notice that like Nereis it has a pro-
trusible introvert, in this case furnished with two pairs of
horny jaws.
Related to Polynoe is the sea-mouse, a much larger and
handsomer form, which does not occur on the shore rocks,
but is often thrown up after severe storms. In shape it is
even less worm-like than Polynoe, for it has an oval-
depressed body with little sign of segmentation visible
externally. Either because of its beauty, or because it
may be practically supposed to be born of the foaming
breakers which toss it on the beach, it is named after
the fair goddess who* rose from the waves, and is called
Aphrodite aculeata. The body is densely covered with
bristles and hairs, which form a dense felt over the
scales, and at the sides of the body gleam with brilliant
iridescence, changing with every changing ray of light. The
sea-mouse may reach a length of six inches, but is usually
considerably smaller. The peristomium is remarkable
because it has shifted in front of the mouth, and bears
two typical parapodia — a very unusual condition. The
scales number fifteen pairs, as in Polynoe imbricata, and
are similarly arranged, but they are not visible until the
dorsal mass of hairs is removed. The sea-mouse is a very
interesting worm, for it combines wonderful beauty of
colouring with ugliness of form. It is generally found
among weed and rubbish on the shore, and as one turns
over the debris its brilliant hues suddenly flash out in all
the colours of the rainbow. Partly, as I think, because of
the unexpectedness of the colouring, partly because many
people have little appreciation of form in the lower animals,
THE BRISTLE-WORMS. 97
Aphrodite has always had abundant praise lavished on its
beauty. Many people even go so far as to call it the most
beautiful of the PolychsBtes. There is certainly no doubt
as to the beauty of colouring, but for my own part I must
confess to a preference for some of the leaf-worms, which
present a combination of beauties of form, colour, and
motion which is denied to Aphrodite.
As to the habits there is not much to be said, for the
worm lives in mud or sand in deep water, and is not easy
to keep alive. Although it might be supposed that the
thick coating of bristles would render it anything but a
pleasant mouthful, it is nevertheless greatly relished by the
cod and other fish, whose stomachs are sometimes filled with
fine specimens.
There is another common shore worm which is related
both to Polynoe and Aphrodite, but differs markedly in
FIG. 32.— Sthenelais boa. After Johnston.
appearance from both. This is the common sand Polynoid,
Sthenelais boa (see Fig. 32), which lives in sand or sandy
places. It resembles Polynoe and the sea-mouse in having
the dorsal surface covered with scales, but differs very
markedly from both in its elongated shape and numerous
segments. Specimens reaching a length of eight inches are
said to sometimes occur, but the usual length is from five to
six. The body is flat, narrow in proportion to its length,
and hardly tapers at either end, so that the worm looks as
if it had been abruptly truncated in front and behind.
Though the colours are unobtrusive — quiet sandy greys or
browns — yet the size and shape give the worm much greater
beauty of form than that displayed by the ordinary squat
Polynoids. It is common in most places where there is
H
98 LIFE BY THE SEASHORE.
sand, and may be obtained either by digging in the sand,
or, quite as frequently, under stones which are resting on a
bed of muddy sand. It does not throw off the elytra quite
as readily as the common Polynoe, but has almost a worse
fault in the tendency to break into pieces on very slight
provocation. It has, on the other hand, the great advantage
of preserving well, and making a beautiful preparation when
once it can be obtained intact.
Some interesting points of structure may be noticed.
The scales begin on the second segment, and up to the
twenty-sixth segment occur on alternate segments; after
this they are borne on every segment. In addition each
segment bears two small gills which are covered by the
scales. These gills are believed not to be homologous with
dorsal cirri, which are here represented only by the scales.
The last segment of the body bears two extremely fragile
cirri. The worm is sometimes called "brown cat" by
fishermen, who call another sand worm (Nephthys) " white
cat." There is some superficial resemblance between the
two, but the "white cat" has no scales, and is much more
rapid in its movements.
The next family we shall consider is that of the "leaf-
worms" (Phyllodocida?.). The family includes some of the
most beautiful of worms, remarkable alike for beauty of
form, of movement, and of colour. They owe their name
and much of their beauty to the fact that their cirri are
converted into leaf-like plates which are used in swimming.
These leafy plates are often brightly coloured, green tints
predominating in their colouring, and they stand out like
oars at the sides of the body. When the animals move a
wave of motion sweeps down the long rows of oars, while
at the same time the long lithe body sways from side to
side. If we add that some forms possess a lovely changing
p>ieen, in addition to the bright colour seen in repose, it is
easy to understand that the Phyllodocids are often beautiful
indeed.
It is interesting to note some of the differences between
their leafy plates and the scales of Polynoids. In the latter
the scales are attached by a small area usually near the
centre, so that the whole series forms an armature of
overlapping scales, the elements of which are capable of
THE BRISTLE-WORMS.
99
//t
relatively little movement. In the leaf-worms the plates
are attached by one end only, so as to be freely movable.
Both the dorsal and ventral cirri are modified to form these
plates, but the dorsal are the larger.
Besides serving as locomotor organs, the
cirri have another function. When the
worms are irritated or attacked, they
pour out an abundant jelly-like secretion,
which examination shows to be produced
by glands on the plates. It is probable
that this mucus protects them from some
enemies. It is poured out in special
abundance when one employs any of the
ordinary reagents to kill the worms, and
in consequence spoils them very much as
specimens. Inrsome species the plates fall
off almost as readily as do the scales of
Polynoids.
Of the type genus Phyllodoce we shall
consider two species only, which differ
from one another in appearance very
markedly. These are the small brown
Phyllodoce maculata, and the large green
P. lamelligera. The former, or spotted
leaf-worm, occurs freely among the shore
rocks, especially among sand. It reaches
a length of from three to four inches, but
is very slender in proportion to its length,
a worm of about three and a half inches
long being not more than about one-tenth
of an inch broad. It is an active little
creature, wriggling over the surface of the
sand, or swimming through the water
with all its plates in active movement.
The colour is not unlike that of sand,
being a pale brown with three very dis-
tinct dark brown spots on each ring. As in all species of
Phyllodoce^ the head (see Fig. 34) bears four small tentacles
near its anterior end, and a pair of distinct dark eyes near
its posterior margin. Behind the head proper are three
segments more or less fused, and bearing in all four pairs
or Phyllodoce lamel-
llgera.
100
LIFE BY THE SEASHORE.
FIG. 34. — Head and intro-
of tentacular cirri. The remaining segments bear parapodia
consisting of a single branch, with leaf-like ventral and
dorsal cirri. The bristles are relatively
few in number. In living specimens
you will notice the frequent eversion of
the capacious proboscis, or introvert,
which has no jaws, but bears small pa-
pillae. This is an extremely common
worm, and one almost certain to be en-
countered. Though the colouring is
sober, it is a pretty little creature, and
repays careful examination.
The other species mentioned, the
paddle -worm (P. lamelligera), is very
much larger, and is one of the hand-
somest of our British wDrrns (see Fig.
33). It has been known to reach a
vert (i) of Phyiiodoce length of two feet, but is more usually
lamelhgera. After Ehlers. °, . , ' . 1,1
twelve inches or under. It is a bulky
worm with a flattened body, usually about a quarter of an
inch wide, and is green in colour with iridescent metallic
tints. It lives beneath stones near low-tide mark, and in
many places is not uncommon. Like the preceding species,
it has a capacious introvert furnished with papillae, but with-
out jaws. The number of tentacles and cirri is the same as
in the preceding species, but it differs from this in the shape
and position of the dorsal plates. There can, however, be
no possibility of confusion between the two species, for their
general appearance is very different.
We shall not consider any other species of Phyllodoce,
although others do occur on our shores, but may just notice
some points as to the genus as a whole. It is a large genus,
and is, indeed, by some authorities split up into sub-genera
denned by the characters of the head, but the specific
characters are often very indistinctly marked. In Poly-
chsetes in general the characters relied on in discriminating
species are usually the numbers and characters of the
bristles, the characters of the parapodia, and the structure of
the head and introvert when this is present. But in the
genus Phyllodoce, while some of these points display great
constancy, others seem to display much individual varia-
THE BRISTLE-WORMS. 101
bility. Thus, to take one example only, it is believed by
some authorities that there are two "paddle-worms," one
called P. lamelligera and the other P. laminosa, while
others maintain that these two are one, or are mere varieties
of one species. The curious point is that those who regard
them as distinct are by no means agreed as to the dis-
tinguishing features of each, a fact which certainly suggests
the occurrence of variation. Other authorities believe that
very many of the so-called " species " of Phyllodoce are mere
varieties, and that one may, as it were, pick out a few
dominant types, round each of which a number of more or
less clearly defined varieties group themselves. The point
is a very interesting one.
The next genus — Eulalia — differs from Phyllodoce in the
presence of an additional tentacle, so that the head bears
five instead of four of these. Curiously enough, however,
apart from this prime difference, there is an extraordinary
parallelism between the " species " of Eulalia and the
"species" of Phyllodoce. Thus there is a species of Eulalia
which, except for its tentacle, resembles in almost every
respect Phyllodoce maculata, while our commonest Eulalia
(E. viridis) has a twin brother in a green Phyllodoce. As
the extra tentacle in Eulalia is often by no means easy to
see, there is no difficulty in understanding that this fact has
tended to add greatly to the confusion of nomenclature and
description, so that the Phyllodocids in general form a very
difficult family, and one in which there is still much to be
done.
We shall only describe one species of Eulalia, and that is
the common and beautiful E. riridis, the green leaf-worm.
It is a small wTorm, three inches or less in length, of a bright
green colour, which is peculiarly vivid in females filled with
eggs. It is common in rock crevices at many parts of the
coast, and is readily recognised at a glance as a Phyllodocid
from the green leafy plates which in life are in constant
movement. The fact that it is a conspicuous worm and
lives considerably above low-tide mark makes it the most
obvious of the Phyllodocids, for P. lamelligera is local and
P. maculata is so slender and inconspicuous as to be readily
passed over without notice. In spite of its beauty and
fragile appearance, Eulalia, like the other Phyllodocids, is a
102 LIFE BY THE SEASHORE.
carnivorous animal, living chiefly upon other bristle-worms.
It is also of interest because of the beauty of the egg masses
which are laid in spring. Everyone must have noticed the
little sacs of transparent jelly, filled with minute bright
green eggs, which are so common in spring on the shore
attached to stones, shells, and weed. In shape they are like
very large grapes with a soft jelly stalk. These are the eggs
of Eulalia viridis, and if you pierce the jelly and examine a
few of the freed green specks under the microscope in
water, you will probably see the little top-shaped larvae
creating miniature whirlpools by the active movements of
their long cilia. These peculiar larvae occur in the life-
history of most bristle-worms, and also of Molluscs. They
are active little creatures adapted for life near the surface of
the water, and thus are probably important in the distribu-
tion of sedentary forms like most of the bristle-worms. At
least the early stages of development can be followed in the
eggs of the Phyllodocids, and their egg packets are certainly
the most conspicuous and the most readily found of the eggs
of Polycheetes.
It is, perhaps, hardly necessary to describe Eulalia viridis
in further detail. The fifth tentacle arises far back on the
head, between the two eyes, and as in Phyllodoce there are
four pairs of tentacular cirri, or tactile processes, on the
head. The dorsal plates are pointed and elongated, and the
ventral similar but smaller. The bright green colour is
very characteristic, and makes the worm easy to recognise.
KEY TO WORMS DESCRIBED IN THIS CHAPTER.
Class. — CHJETOPODA (bristle-worms).
Order. — POLYCHJSTA. The bristle-worms of the sea.
Body short, flattened,
with parallel sides
— Polynoe.
Body oval and de-
Worms with flat scales,
or elytra, on their \ Fain. Aphroditidte.
backs.
pressed, covered dor-
sally with a felt of
bristles — Aphrodite.
Body elongated and
worm - like. Head
with three tentacles
— Sthenclais.
THE BRISTLE- WORMS. 103
Worms with leafy plates ^l ( Head with four ten'
taeles- I tacles— Eulalia.
CHARACTERS OF SPECIES.
Fam. Aphroditidse.
Polynoe. P. imbricata has fifteen pairs of scales, which fall off very
readily. The projecting bristles have a length equal to half
the width of the body.
Aphrodite. A. aculeata has fifteen pairs of scales beneath the felt
of bristles. There is a small median tentacle and two long
palps on the head. The body tapers posteriorly.
Sihenelais. In S. boa the head has three tentacles, a pair of long
palps, and four eyes. The first segment bears three pairs of
cirri.
Fam. Phyllodocidse.
Phyllodoce. In P. maculata the body is very slender, the dorsal
plates are rounded. In P. lamelligera the body is broad and
massive, and the dorsal plates are oval or heart-shaped.
Eulalia. In E. viridis the body is bright green, and the dorsal
plates are narrow and pointed.
All the worms mentioned in the chapter are widely distributed
throughout the British area.
CHAPTEE VI.
BEISTLE-WORMS— continued.
The Nereids — Formation of Heteronerete — Characters of Heteronereis
— The common species and their habits— Two sand-worms, Neph-
thys and Glycera — Their structure and habits — The rag- worms —
The worm Cirratulus — The Terebellids and the process of tube-
building — The tube of Pectinaria — Trophonia plumosa— The
Sabellids and Serpulids— The tube-building of Sabellaria— The
"living film " — Ribbon- worms— Polyzoa.
THE family with which this chapter opens is one contain-
ing a number of large and common forms. It is the
!N"ereida3, to which the genus Nereis, described in the pre-
ceding chapter, belongs. As intimated there, by far the
commonest species, on Northern coasts at least, is Nereis
pelagica, which occurs abundantly between tide -marks, vary-
ing in size from two to six or more inches. It is usually of
a fine bronze colour, and is an active and handsome form,
showing not a little colour variation.
As to the species marks, the easiest
way of recognising it is to examine
the little teeth, or paragnaths, on
the introvert £see Fig. 35), but it is
also characterised by the great size
of the palps, the elongated shape
of the head, the long dorsal cirri,
and the arched back. It may be
well to notice that in Nereis the
palps are readily distinguished from
tentacles by their shape and size.
This is not invariably the case,
but the two may always be dis-
tinguished by the fact that while
104
a 6
FIG. 35. — Upper (a) and
under (6) surface of the
introvert of Nereis pela-
gica; j, jaws. The dark
specks are the paragnaths,
which vary slightly in
different specimens. After
Ehlers.
THE BEISTLB-WOBMS. 105
the palps arise from the ventral surface, the tentacles are
dorsal. Perhaps one of the most interesting things about
this, as about most of the other species of Nereis, is the
changes which it undergoes at sexual maturity. When hunt-
ing under stones for specimens you may not infrequently
find one which is peculiar in that while the anterior part of
the body has all the usual characters, the posterior region is
strikingly different in appearance, so that the worm looks as
though it were compounded of two dissimilar worms. The
colour is also remarkable, for the body is bright green
anteriorly, and pure pink in the posterior region. If you
examine the posterior region more closely, you will find that
the difference in appearance is largely due to the modifica-
tion of the parapodia. These have greatly increased in size,
and their different regions have developed leafy outgrowths,
which convert the parapodia as a whole into swimming
organs. The resultant change in the external appearance of
the animal is so striking that the modified form was for long
supposed to belong to a distinct genus, and was called
Heteronereis. It is now known to be merely the mature
form, and owing to the fact that it is adapted for a free-
swimming existence no doubt assists in the distribution of
the species. It will be remembered that in the Coelentera
the sessile sea-firs bud off active swimming- bells, which
produce the ova, and by their power of swimming ensure
the distribution of the species. In certain small worms
belonging to the genus Syllis and to allied genera something
quite analogous occurs, for the worms bud off new indi-
viduals, which are modified for a free-swimming life, and
which contain the eggs and spermatozoa. In another very
curious worm, the "Palolo" of Samoa and Fiji, a portion of
the body becomes modified, much in the same way as in
Nereis, but the modified portion separates off, and swims
away, leaving, it would seem, the anterior region behind at
the bottom. The separated portions of the worm appear at
the surface of the water in extraordinary numbers at certain
seasons, and are caught and eaten by the natives. The
" swarming " only lasts for a short time, and it is probable
that the worms die after laying their eggs, while the
"heads," which have remained at the bottom among the
coral blocks, bud out new bodies, and eventually repeat the
106 LIFE BY THE SEASHORE.
whole process. In Nereis, though the genital products occur
only in the posterior region of the body, this part does not
separate off as in the Palolo.
In N. pelagica the modifications undergone by the mature
female are less marked than those in the male. The female
Heteronereids are very much larger than in the male, and
have fewer of the segments modified. The modification is
also less marked. It is not uncommon to find large speci-
mens with a few merely of the posterior segments under-
going incipient modification. One striking characteristic of
both sexes of Heteronereids is the presence of a sensitive
rosette on the last segment of the body. Further, in the
male the eye increases in size and becomes beautifully
coloured, and, as already noticed, the colours in both sexes
become brighter. These very interesting changes can be
followed very readily on the shore, especially in the
North.
Besides N. pelagica, two other species occur free on the
shore in most places, in addition to N. fucata, a handsome
species found in shells inhabited by hermit-crabs. The two
species are N. dumerilii, a rather small form with very long
cirri, which forms a tolerably firm tube, and N. cultrifera, a
large form in which the dorsal cirri are short, and the back
less well arched than in N. pelagica. Both species occur in
situations somewhat similar to those affected by N. pelagica,
and will be generally found among gatherings of the latter.
The distinguishing features are noted at the end of the
chapter. To get N. fucata, on the other hand, one must
collect a few large specimens of hermit-crabs, especially
those which occur in whelk shells, and are, therefore, nearly
full grown. Such specimens are sometimes flung on the
beach by storms, and though often dead or moribund, are at
times living and active. If still alive, put your specimens
in clean water, and after a time you will not improbably be
rewarded by seeing the hermit entirely recover his disturbed
equanimity, and sit, metaphorically speaking, at his ease on
his doorstep placidly twirling his long feelers. You may
further see protruded above the hermit's head the long
feelers and stout palps of a brick-red Nereis. The worm
does not completely quit the shell, but protrudes the ante-
rior part of the body, and no doubt shares in any food
THE BRISTLE-WORMS. 107
which may be going. When the hermit is alarmed and
retreats, the worm does the same, and then retires to the
topmost whorl of the shell, entirely out of sight. So far
does it retreat that it is by no means easy to extract it from
a shell quitted by the hermit, and a very vigorous shake is
required before the attic tenant will show himself. There
is usually only one worm present, but I have found two in
one shell. The percentage of cases in which the worm
occurs also varies greatly according to the locality ; off the
Isle of Man it is said to be present in 90 per cent, of the
whelk shells inhabited by the hermit-crab, while in other
places it is relatively rare. It is not entirely confined to
hermit-crab shells, but occurs occasionally free, and occa-
sionally in empty shells.
The living animal is very easily recognised by its colour
and markings. It is of a beautiful red tint, with two pure
white bands on the dorsal surface. After death, however,
the colouring soon fades, whatever the preservative em-
ployed. In structure the worm differs from the two
preceding in that the parapodia are not all similar, the
posterior differing from the anterior. In the posterior
segments especially the uppermost lobe of the parapodia is
elongated, arched, and swollen. It is highly vascular, and
no doubt functions as an efficient respiratory organ.
We shall describe only one other species of Nereis, and
that is the large and handsome Nereis virens. It is a green
worm, differing from the other species described in the
presence of large leafy plates in the dorsal region of the
parapodia. The plates are not expansions of the dorsal
cirrus, like the plates of Phyllodocids or the scales of
Polynoids, but are expansions of the dorsal lobe itself (cf.
N. fucata). The structure of the parapodium altogether
suggests to some extent the modified parapodia of the
"Heteronereis" of other species, and it is interesting to note
that though N". virens does become converted into a Hetero-
nereis, the changes are relatively slight. The worm reaches
a length of over a foot (up to eighteen inches), and when
the large black jaws are fully protruded has quite a formid-
able appearance. It is said to be called the " Creeper," and
to be used as bait on some parts of the coast. The leafy
plates, like those of Phyllodocids, secrete an abundant
108 LIFE BY THE SEASHORE.
supply of mucus which is here used to line the burrow.
The worm occurs between tide-marks, and is sometimes to
be found by digging near the rocks, while at other times it
may be found swimming freely. It is a somewhat local
form, but Granton and St. Andrews may be mentioned as
places where it is to be found.
It is hardly necessary to enter in detail into the characters
of the worm ; the size, the colour, and the structure of the
parapodia render it easily recognised.
The species of Nereis are very abundant on the shore
rocks, and are certain to be encountered in shore hunting.
With the Polynoids and the Phyllodocids they constitute
the commonest and most highly developed of the large free-
living worms of the shore. In all three sets the body is
very uniform in structure throughout its length, the head
is well furnished with various tactile processes, and the
parapodia are large and well developed. In studying the
bristle-worms, therefore, it is well to become familiar with
the common members of these three families before pro-
ceeding to the more difficult sedentary forms. Related
to these three families are two small families of sand-
inhabiting worms, which have much less conspicuous tactile
processes on the head, and considerably less brightness of
tint. These are the Nephthydidse, including Nephthys
hombergii, the " white cat," and the Glyceridoe, including
Glycera capitata, both interesting and curious worms.
Both are genuine burrowers, to be found along with many
other worms by digging in sand marked by worm -tracks
and burrows. When turned up by the spade both (Us-
play active movements, during the course of which the
enormous introvert is constantly protruded and retracted,
with a rapidity which is astonishing, and even alarming
to timid people. The performance suggests a juggler's
trick, in that the ejected proboscis seems bigger than the
worm. In both cases the introvert is an important instru-
ment in burrowing.
The " white cat " (Nephthys hombergii) is common in the
sand in most places, and is valued by fishermen as bait.
The colour is greyish and sandy, but the body displays fine
opalescent tints. Usually the worm does not reach a length
of more than three to four inches, and it is remarkable in
THE BRISTLE-WORMS.
109
Fio. 36. — Foot, or
parapodium, of
Nephthys hom-
bergii. d, dorsal,
and v, ventral lobes
of foot with bristles
and thin plates, p ;
g, gill ; c, ventral
cirrus, the dorsal
is absent. After
Ehlers.
being quadrangular in section. The dorsal surface is flat,
and so also is the ventral, save that it has
a very distinct median groove. The foot
is of remarkable structure (see Fig. 36).
When fully protruded the introvert is
seen to be furnished with numerous
papillae. There are also two jaws, but
these are small and are not protruded.
The worm is readily recognised by its
opalescent colours and its very active
movements, and is a common form which
ought to be found and studied.
While digging for Nephthys one may
occasionally turn up an elongated worm
with a body which narrows rapidly in
the posterior region to form a long tail.
The colour is pale yellowish, and the
animal has an eminently characteristic
habit of coiling itself into a spiral on
the slightest touch. The head is extra-
ordinarily long and pointed. An animal
displaying these characters is a species of Glycera, and the
commonest species between tide-marks is G. capitata. In
most species there may be seen on the dorsal region of the
feet in the living worm, small sac-like gills in which the
blood corpuscles circulate rapidly, but these are absent in
G. capitata. The long introvert is crowned by four dark
jaws, which in the large Glycera of deep water (G. giganted)
are strong enough to pierce the skin. The different species
are distinguished by the presence or absence of gills, and
the minute structure of the parapodia.
The most interesting point in regard to the habits of
Glycera is the strange way in which it throws the body
into a close spiral. Like most sand-inhabiting worms it is
not easy to keep alive in captivity.
In the reduction of their tentacles, palps, and cirri,
Nephthys and Glycera lead up to the next genus we shall
consider. This is the genus Nerine (rag-worms), which
includes worms without any trace of palps or tentacles.
The peristomium bears a single pair of long tentacular cirri,
the dorsal cirri are converted into gills, and the ventral cirri
110 LIFE BY THE SEASHORE.
are absent. As compared with any of the preceding worms
the parapodia are reduced, and only project slightly at the
sides of the body. Both the common species inhabit muddy
sand, and both are extraordinarily brittle, breaking into
pieces on the slightest provocation. Common as the worms
are it is in consequence very difficult to get a complete
specimen. The gills (dorsal cirri) are carried curved over
the back, and being filled with red blood are in life very
conspicuous objects. The tentacular cirri are broad and
long, and in life are in constant movement. Like other
parts of the body these are very apt to be thrown off by
captive specimens. There is little difficulty in distinguish-
ing between the two species. The larger, N. coniocephala,
is said to attain a length of eight inches, but on the
East Coast at least is usually much smaller; the smaller,
.ZV. vulgaris, is three to four inches long. The larger is the
handsomer species, for it is usually of a fine green colour,
which contrasts with the scarlet gills. In Nerine vulgaris
the body is usually yellowish red, but also exhibits a ten-
dency to become green. It will be noticed that the surface
of the gills is increased by a membrane (the podal mem-
brane) which extends up the gill, its size differing in the
two species. The other distinguishing characters are given
at the end of the chapter.
In Nerine the parapodia project slightly at the sides of
the body, but in the remaining worms they are at most
represented by small tubercles bearing the bristles. The
worms are almost either burrowers or tube-formers, and
very frequently the anterior end, which projects from the
tube or burrow, differs markedly from the posterior.
The first of these worms which we shall consider is
recommended by its great abundance on the shore rather
than by any beauty or great interest. In turning over
stones on the rocks, the beginner often tries stones firmly
bedded into mud or sand, and therefore without any under-
lying cavity. When such stones finally yield to a strong
pull, they reveal an odorous substratum of mud which is
usually traversed in all directions by slender scarlet threads
moving about like living worms. A little investigation will
show that these are the tentacular filaments and gills of a
reddish worm embedded in the mud. If molested the
THE BRISTLE-WORMS. Ill
worm not infrequently throws off these filaments, which
retain their activity for a long time, and often greatly
puzzle the beginner. This worm is Cirratulus cirratus, and
is often exceedingly common in black sand or mud under
stones. In the early part of the year the worms quit the
mud, and may be found freely exposed on the rocks in the
act of spawning. The eggs are of yellowish colour, and as
in most worms are surrounded by a jelly-like substance.
As in the case of not a few littoral animals, it is only at
the breeding season that one is able to get any adequate
idea of the extraordinary number of individuals which
occur between tide-marks. In the Firth of Forth in Feb-
ruary I have seen the rocks literally covered with the
worms, while at other seasons they can only be found by
careful search.
It is not necessary to say much of the characters of the
worm. The prostomium is long and pointed. Behind it is
a transverse row of tentacular filaments, which in life are
distinguished from the gills by their paler colour and their
"curled" appearance. After death it is not easy to dis-
tinguish between gills and filaments. The gills are of
course modified dorsal cirri. They are long, slender, and
filamentous, and the colour is bright red. They are- most
numerous and most regularly arranged on the anterior
segments; but scattered gills occur throughout the greater
part of its length. Apart from the gills, the parapodia are
merely represented by papillae at each side of the segments
bearing small bristles. On the East Coast at least the worm
does not usually exceed three to four inches in length.
Much more interesting than Cirratulus are the Terebellids,
or sand-masons, which build long tubes neatly plastered over
with particles of sand, shell, and stone. In walking over
the sand after the tide has ebbed, one very often finds
great masses of the sandy tubes of these worms. Some of
these tubes are fringed at the top with branched sandy
threads, so curious in appearance that the inexperienced
commonly regard the tube as some kind of an animal.
These are the empty tubes of TereMla conchilega, the sand-
mason, and sometimes occur on the shore in extraordinary
abundance. They are always empty, however, and usually
not more than a few inches in length. We need not,
112 LIFE BY THE SEASHORE.
therefore, mourn the untimely decease of innumerable
worms, for it is only a portion of the house which has
been sacrificed to the force of the breakers ; and the worms
are tireless " masons," and can soon repair the damage. To
find them living we must seek those sandy stretches which
sometimes occur among the shore rocks. Here we find the
tubes sticking up vertically from the sand, with their stiff
fringe and about an inch of tube above the level of the
sand. It is easy to imitate the action of the breakers and
pull up the tube ; but the prudent worm has learnt its
lesson well, promptly retreats to the bottom of its tube, and
leaves you with a few inches of empty tube in your hand.
The worms often measure as much as ten inches in length,
and the tubes are always longer, often much longer, than the
worm. It is in consequence a somewhat difficult process
to obtain a complete specimen, especially when we add to
the other difficulties the fact that the worms are exceedingly
fragile, and often rupture at a touch. One habit, however,
aids the process of extrication. The worms show a marked
preference for rock crevices, and in jointed rocks often
occupy the widest of the joints. Such jointed rocks are
often easily split into blocks, and in this way, with the help
of a geological hammer, it is sometimes possible to get very
fine specimens. There are a considerable number of Tere-
bellids to be found on the shore rocks, and many of these
do not burrow so deeply as Terebella conchilega, and may
be more easily obtained, but we shall confine our description
to this handsome species.
Let us suppose, then, that your excavations have been
crowned with success, and an intact specimen of the desired
worm lies before you (see Fig. 37). The colour varies, but
is often a beautiful rosy tint, the tufted gills being a bright
scarlet. The head bears numerous long tenta:ular filaments
like those of Cirratulus, which in life are protruded from
the opening of the tube. They collect the sand grains and
other particles which when mixed with secretion form the
tube, and are sheltered and perhaps protected by the stiff
fringe of the tube. The first segment (peristomium) forms
a bilobed lower lip which is used as a trowel to plaster
the tube. As might be expected from the tube-dwelling
habit the gills are confined to the anterior segments, where
THE BRISTLE-WORMS.
113
they can be freely exposed to the purifying action of the
water. They further differ from those of Cirratulus in
being branched and comparatively short. Some other
adaptations to life within a tube are almost equally obvious.
Thus the parapodia are greatly reduced, and the bristles
modified so as to suit the needs of a tube -inhabiting
worm.
On the anterior segments, from four to twenty-one, there
are in all seventeen
pairs of papillae
bearing fan -shaped
tufts of bristles.
The papillae repre-
sent the dorsal lobes
of the parapodia,
and are absent from
the narrow posterior
region of the body;
they no doubt assist
the animal in mov-
ing up and down
its tube. The ven-
tral lobes of the
parapodia are repre-
sented by elongated
vascular bands at
the sides of the
segments, each of
which bears from
eighty to one hun-
dred mirmtp Viookq FlG- $I.—Terebella removed from its tube. Note
area minute n >OKS. t^e long tentacleS) the tufted gills> and the
Ihese nooks are difference between the anterior and posterior
modified bristles regions of the body-
and are present in various forms in the majority of tube-
inhabiting worms. Very little observation on the rocks
will acquaint you with the fact that in most cases a
tube-inhabiting worm can withdraw into its tube on an
alarm with extraordinary rapidity. In a worm like Terebella
the process is assisted by many thousands of hooks, each
bearing secondary teeth. The hooks are very small, and
can just be made out in a good light with a strong lens.
114 LIFE BY THE SEASHORE.
Their presence may often be demonstrated even when they
cannot be seen, by drawing a needle over the hook-bearing
area, when a slight grating sound will be heard. Unlike
the dorsal bristles these ventral hooks occur throughout the
body, except on the extreme anterior segments. In the
anterior region in the living worm it will be found that
the ventral surface is very bright red in colour, and glandular
looking. This is due to the presence of fourteen to twenty
pairs of " gland-shields," which secrete the mucus which is
the basis of the tube.
A considerable number of Terebellids live on the shore,
differing from one another chiefly in the structure of the
gills, the number of dorsal lobes, of gland-shields, etc.
Small specimens of Terebella or of others will live for a
time in confinement, when the process of tube-building can
be watched. The worms may sometimes be induced to
build an incomplete tube along the side of the aquarium,
so that the worm may be watched through the glass within
its tube. Like other tube-inhabiting forms, Terebella con-
cliilega shows considerable power of adapting its "masonry"
to the special conditions in which it may be placed ; thus
specimens living in deep water construct tubes which in
several respects differ from those of shallow-water forms.
Another interesting tube-worm, smaller and less abundant
than Terebella, is Peciinaria belgica (see Fig. 38), which is
to be found in sandy pools. Its tube is short, usually about
one and a half inches, is without a fringe, but displays a
neatness of workmanship which makes the tubes of Terebella
seem coarse and clumsy. It is constructed of sand grains,
which are all of the same size, and are smoothly and evenly
worked into a plaster of mucus, so as to form a beautiful
mosaic. The tube is firm enough not to collapse when the
tenant is removed, and is open at both ends. The large end
corresponds to the head of the worm, but it is this end which
in life is buried in the sand, the narrower posterior end pro-
jecting from the surface of the sand. The worms live well
in captivity, and the habits may be readily observed in
specimens placed in a glass jar with clean water and a layer
of sand. In such specimens you should see a beautiful
crown of golden bristles (b in Fig. 38) protruded from
the large end of the tube, and used as a trowel to excavate
THE BEISTLE-WORMS.
115
a hole in the sand. If the burrowing occur near the glass,
the short tentacles (te) will be seen in addition to the
golden bristles. When removed from its
tube, the worm is seen to be short and
stout, with relatively few segments, and a
peculiar terminal plate (tp), which serves
to close the posterior end of the tube. The
prostomium bears tentacles like those of
Terelella, and is much less conspicuous
than the peristomium, which carries the
bristles, and projects in the form of a
collar. There are two pairs of gills (g).
As in TerebeUa, the parapodia (p) are
represented by dorsal clusters of bristles
and ventral hooks. The worms do not
quit their tubes except at the approach
of death, but are capable of some amount
,. , ' . r. ,, . , , .., FIG. 38. — Pectinarut
01 locomotion, carrying their tubes With belgica removed from
them. In Terebella, on the other hand, %**&*££%
the tubes are permanently fixed in one text. After Malm-
spot.
Very different from Terebella or Pectinaria is the fisher-
man's lob-worm (Arenicola piscatorum), whose appearance
and habits we have already described. It is abundant in
most suitable places, except where incessant persecution has
almost exterminated it, and as bait has, or had, considerable
importance to fishermen.
Though we have necessarily omitted many not uncommon
shore worms, there is one interesting if inconspicuous worm
which deserves special mention. This is Trophonia plumosa,
which is found not infrequently in muddy places on the
shore rocks. It varies in length from two to four inches,
and is a Northern form, which is both more abundant and
reaches a greater size in the Northern than in the Southern
waters of our islands. At first sight it may seem both an
uninteresting and a puzzling form, for there is almost nothing
in the external appearance to take hold of. The colour is a
dull drab, and the only striking character is the great pro-
jecting sheath of bristles at the anterior end. Nevertheless
the worm is interesting enough. The head is usually re-
tracted, but when protruded it is seen to bear two long
116 LIFE BY THE SEASHORE.
tentacles, pinkish or yellow in colour, and eight short gills
coloured by the green blood which they contain. The great
head sheath is formed by the dorsal bristles of the anterior
segments, but similar though shorter bristles occur on the
other segments. The ventral parts of the parapodia are
represented by projections bearing curious hooked bristles
of remarkable structure. The surface of the skin is
roughened by numerous papillae, which in an allied form
(Siphonostoma) secrete a jelly-like investment absent in
Trophonia. So far as my" experience goes, it is a sluggish
animal, not displaying much activity of any kind, but
nevertheless it is zoologically full of interest.
The next family to be considered is that of the Sabellidae,
which includes a large number of common and beautiful
worms. They usually construct tubes of sand or mud, and
are characterised .by the presence of a " crown " of beautiful
gill filaments. These are formed by the splitting up of the
palps, and are of a beautiful green colour owing to the
contained blood. The base of the crown is concealed by
the peristomium, which forms a projecting collar. As in
Terebellids the parapodia are represented by bristles and
booklets, but the booklets are ventral in the anterior nine
segments (thorax), and dorsal in the posterior segments
(abdomen). We cannot describe even the more common
Sabellids, but may take as an example Dasychone bombyx,
a worm which is easily recognised by the eyes on its gills.
It forms a soft mucoid tube impregnated with particles of
sand or mud, and attached to shells or stones. The worm
is short (1-1J inches), of a reddish brown colour, and
furnished with a beautiful crown of light -coloured gill
filaments. When examined with a lens these filaments are
seen to bear dark- coloured eyes, arranged in pairs along the
dorsal surface of each filament. Owing to the presence of
these eyes the worm is extraordinarily sensitive to varia-
tions in intensity of light, and disappears into its tube like
a flash if a shadow falls on it. Like other Sabellids the
worm, if it can be kept alive, is a most delightful inhabitant
of an aquarium, where it may be watched protruding its
lovely crown from the tube, so that all the filaments are
bathed with water.
Closely related to the Sabellids are the Serpulids, which
THE BRISTLE-WORMS.
117
differ from them in possessing a limy tube which can usually
be closed by an operculum, and in the presence of the so-
called " thoracic membrane," which is a delicate membrane
at either side of the thorax used in smoothing the inside of
the tube. There are a great number of Serpulids just as
there are of Sabellids. The conspicuous white limy tubes
are very common objects on shells and stones, both on the
rocks and among the wreckage flung on the beach, and are
familiar to most people, but the worms themselves are less
well known. In deep water Serpula itself is very common,
but on the shore
rocks a form called
Pomatoceros trique-
ter is the most fre-
quent. Notice the
distinct keel which
runs along the dorsal
surface of the tube,
and ends in a dis-
tinct spine over-
hanging its opening;
then select a few of
the largest speci-
mens you can find,
and place them,
with the shells or
stones to which they are attached, in a vessel with clean
water. After a period of patient waiting you will see a
crown of brilliant gills protruded, whose white ground colour
is relieved by splashes of crimson, orange, or blue. As the
filaments separate out in the water, notice that, as in
Sabellids, they arise in two clusters. Note further that in
one of the clusters the filament nearest the mid-dorsal
line is converted into a stopper, or operculum, borne
on a stalk. The corresponding filament at the other side is
aborted. If the worms be not alarmed, they will protrude
themselves far enough to show a collar like that of a Sabellid,
and the wavy thoracic membrane. In the thoracic region a
blue tint usually predominates. By carefully breaking the
tube it is possible to remove the worm without injury, so as
to display the whole body. Note then the general resem-
Fio. 39 —Serpula vermicularis within its tube.
o, operculum ; g, gills ; t, tube.
118 LIFE BY THE SEASHORE.
blance to a Sabellid, and also the character of the
operculum.
Two other common Serpulids may be named without
description. These are the tiny Spirorbis, which forms its
coiled white tubes on Fucus, and is often very abundant,
and Filigrana implexa, a social form whose narrow, inter-
lacing tubes are often very conspicuous on the shore rocks.
The last worm we shall describe is Sabellaria alveolata, a
curious and interesting form often very abundant on the
shore. It is not closely related to the preceding worms,
and forms a very firm but irregular sandy tube. These
hard tubes are sometimes found singly on shells and stones,
but in places where the worm really flourishes, numbers of
tubes occur together, so that the worms build up blocks of
what looks like coarse porous sandstone. These blocks are
hard, and the worms delicate and fragile, so that it is by no
means easy to obtain perfect specimens.
Before examining worms removed from the tubes, watch
some uninjured specimens within their tubes. They will be
seen to protrude from the tube a crown of bristles, similar to
those of Pedinaria but less brilliant, and also numerous
tentacles. The tubes differ, however, from those of Pectin-
aria in being quite immovable.
In the specimens removed from their tubes notice that
the body is sharply bent, so that the posterior region with
its terminal aperture lies at the opening of the tube close to
the mouth. The worms are not more than an inch long, and
the anterior thickened region is usually of a bright purplish
tint, while the narrow reflexed posterior region is paler in
colour. The peristomium has grown right forward over the
head and bears the prominent bristles. The prostoinium,
as in Sabellids, bears numerous gill filaments, but in addi-
tion there are dorsal cirri which act as gills (cf. Terebellids).
There are many other structural peculiarities too difficult to
be discussed here, but the hardened masses of tubes, the
purple colour, and the peculiar shape are so characteristic
that there is little difficulty in recognising the worm.
In concluding this survey of the bristle-worms it may be
well to point out that their great abundance makes it very
difficult to mention more than a few representative forms.
They occur everywhere on the rocks, and are adapted for all
THE BRISTLE-WORMS. 119
sorts of lives, but as most are relished as food by the larger
shore animals so most either form tubes or burrows, or seek
convenient lurking-places. Though some, like the Phyllo-
docids, can swim with ease, in the general case the bristle-
worms when they possess any power of locomotion are
creepers, using their parapodia as feet. The purely seden-
tary forms live on minute microscopic particles, found in
water or in sand, but the active jaw-bearing forms are
carnivorous. In the resting condition the jaws lie far back
in the buccal cavity, but when in use they, with the buccal
sac, are rapidly everted, and can be as rapidly withdrawn.
The beauty of colouring and of form we have already
frequently emphasised.
In view of the frequent difficulty of identification a few
notes on likely habits for the different species may be wel-
comed. In rock crevices, or under stones which roof in a
cavity, one may expect the paddle-worm (Phyllodoce lamel-
Ugera), the green leaf-worm (Eulalia viridis), the creeper
(Nereis virens), and other species of Nereis (N. pelagica,
N. cultrifera, etc.). But for these smaller species of Nereis
the most likely spots are roots of Laminaria, where many
other worms also occur. Under stones resting on sand one
finds species of Polynoe, Phyllodoce maculata, Sthenelais
boa, and TropTionia plumosa ; but Phyllodoce maculata and
Sthenelais are as common in sand itself. Stones resting on
mud form favourite lurking-places for Cirratulus. By
digging in sand one may obtain Arenicola, species of
Nephthys, Glycera, Nerine, as well as other forms. Of the
tube-dwellers, the numerous Terebellids, the curious Sabel-
laria, and the comb- worm (Pectinaria) all form their houses
of sand. The Sabellids have usually tubes made of mud,,
while the Serpulids make white limy tubes. The excep-
tional habitat of Nereis fucata — within the shell of the
hermit-crab — should also be noticed.
As already noticed, apart from the bristle-worms, other
"worms" occur on the shore rocks. A few only of these
can be mentioned. There are first some interesting leaf-like
flat worms known as Turbellaria, of which a common
example is Leptoplana tremellaris, the "living film." It is
a charming little creature barely an inch in length, of a
delicate brownish tint, and so thin that it is really a mere
120 LIFE BY THE SEASHORE.
film. It is not uncommon under stones on the shore, but
requires a trained eye to distinguish it. When turning over
stones in search of worms it may be that on the upturned
surface, among sponges, tunicates, and what not, you are
struck by a delicate film which glides over all obstructions
with the smooth movement of a drop of water over a
polished surface. Slip a blunt knife carefully beneath it,
and drop it into your collecting-bottle. You will notice that
it swims through the water by vigorous flaps of the body,
with a motion which has been compared to that of a skate.
As it settles again on the edge of the bottle, notice with a
lens that the mouth is on the mid-ventral surface, and that
the greatly branched alimentary canal is visible, ramifying
throughout the greater part of the body. There is no
distinction in appearance between anterior and posterior
end, except that the anterior is furnished with little black
specks — the eyes. The little creature will live for a time
in captivity, and the grace of its movements makes it a
charming inhabitant of the aquarium. The details of
structure are too difficult for our purpose, but the animal
is worth mention, if only on psychological grounds. It is
far from uncommon, and yet many diligent shore hunters
never find it at all. If, therefore, you find no difficulty in
obtaining specimens, you may flatter yourself that you have
acquired the first essential of a shore naturalist — quick
observation.
Sometimes associated with Turbellaria are another set of
flat worms, the Nemerteans, or ribbon-worms. Many of
these occur on the shore, but we shall limit ourselves to
two — the pink ribbon-worm (Amphiporus lactifloreus) and
the great sea-snake (Linens marinus). Under stones at all
parts of the shore one may find the pink ribbon-worm,
living in a slight tube made of sand cemented together by
mucus. It is one to two inches in length, but is extra-
ordinarily contractile. From a bristle-worm it differs
markedly in the absence of bristles or any sign of segmenta-
tion. In the head region the eyes will be noticed, and also
two slits at either side of the head. These are eminently
characteristic of the ribbon-worms in general. So also is
the so-called proboscis, a slender thread which the worm
may be seen to protrude from a pore above the mouth,
THE BRISTLE-WORMS. 121
when alarmed or injured. The worm is very common, and
though not particularly active in its movements, is an
interesting little creature.
The big sea-snake (Linens marinus) is usually only to be
found far out on the rocks near low-tide mark, but is there
common enough. It is a
splendid animal, varying in
length from about three feet
up to many yards, but not
much thicker than the boot-
lace to which fishermen
compare it. The colour is
usually said to be black,
but in reality in life is a
beautiful changing purple,
soft and velvety in tint.
The animal, like all its
allies, is somewhat slimy,
and has a habit of coiling
itself in strange knots, but FIG. 40.— Linens marinus, the sea-snake.
it is nevertheless exceed- fc, head with slits,
ingly beautiful. Readers of Kingsley's Glaucus will perhaps
protest at the adjective, remembering the pages of energetic
vituperation which the author hurls at the unfortunate
animal, but I cannot think that anyone who studies it
without prejudice can fail to be struck by the beauty of the
animal.
Like other ribbon-worms, Linens has head-slits at the
sides of the head, and a long proboscis. It lives well in
confinement, but usually conceals itself under stones, or in
sand agglutinated by its own secretion. Like all its allies,
it is extremely brittle, breaking into pieces on the slightest
provocation. It is in consequence very difficult to obtain
perfect specimens for preservation.
The last group of "worms" we shall mention is the
Polyzoa — curious, much modified forms, which live in colonies,
and are not unlike "zoophytes." The commonest is Flustra,
the sea-mat, which is very common in a dry state on the
beach, and is often called a seaweed. These dried specimens
are in reality merely the houses of the dead worms. A
close examination of a piece of sea-mat will show that it is
122
LIFE BY THE SEASHORE.
made up of very numerous whitish cells or chambers, each
of which once contained a worm. Living Polyzoa are quite
common on the shore rocks. Among those to be found
there in the active condition may be mentioned Flustrella,
which forms a soft brownish encrustation on the stalks of
Fucus, and has its surface covered by numerous spines;
Membranipora, which spreads like delicate lacework over
the broad fronds of Laminaria; and many others. None of
them can be properly studied without the aid of a micro-
scope, and are only mentioned here because they are sure to
be encountered, and may puzzle the student.
KEY FOR IDENTIFICATION OF COMMON BRISTLE-WORMS.
A. Anterior region with well- B. Anterior region with few
developed tactile organs. Para
podia well-developed locomotor
organs, usually with dorsal and
ventral cirri.
A.
ex:}
Dorsal cirri
panded
Dorsal cirri form
filamentous sen-
sory organs
tactile organs, often Avith nu-
merous respiratory organs.
Parapodia reduced, cirri absent,
or dorsal cirri represented by
gills.
f Aphroditidae \See previous
\Phyllodocidse / chapter.
Nereidse
Nereis.
Prostomium short.
Dorsal cirri absent
or indistinct . >
podia
Prostomium iuiig,-v
Gill when pre- VGlyceridee
sent dorsal J
B.
Glycera.
Head without ap-^
pendages. Pros- 1
tomium fused to |
peristomium . j
Prostomium with-\
out appendages,
peristomium
with two tenta- V
cular cirri. Gills
curved over I
back . J
Arenicolidse . Arenicola.
. Spionidae . Nerine.
THE BRISTLE-WORMS.
123
rGills filamentous, \
C' t lid
numerous . /
*
absent. (jUls
Gills branched, ^
segments nu- V
merous . . J
Terebellidse .
filamentous or
Gills branched, 1
branched
segments few, 1
anterior crown j
Amphictenidae
*• of bristles . J
Prostomium with\
palps and nu-
merous tentacles 1
(gills). Anterior f
Chlorhsemidse
bristles forming
a cage for head, j
Prostomium with"1
palps split up to
form a branchial
Tubes of sand or\
>. mud . . f
Sabellidae
crown. Peristo-
mium forming a
Tubes limy
Serpulidse
collar . . j
Prostomium with \
palps split up to
form rows of
.
filaments. Peri-
^ lubes sandy, ag- \
Hermellidce
stomium form-
gregated. . . J
ing a hood edged
with bristles
Cirratulus.
Tercbella.
Pedinaria.
Trophonia.
Dasyclione.
Pomatoceros.
Sabellaria.
CHARACTERS OF SPECIES.
Fam. Nereidse.
Nereis. In N. pelagica the back is strongly arched, the palps are
long, the peristomium or first segment is twice as long as the
second. In N. dumerilii the cirri are very long; the longest
of those borne on the peristomium reaches to the fifteenth
segment. In N. cultrifera the dorsal cirri are short and the
back flattened. In N. fucata, the posterior feet differ from
the anterior, and have a long, arched dorsal lobe. In
N. virens the dorsal lobes of all
plates.
Fam. Nephthydidse.
Nepldhys. In N. Jwmbergii the head is pentagonal, with four
minute tentacles; palps are absent. The peristomium has a
rudimentary foot and a cirrus, but otherwise there are no
dorsal cirri. Lobes of feet widely separated, with curved
gill between.
the feet bear large leafy
124 LIFE BY THE SEASHORE.
Fam. Glyceridse.
Glycera. Prostomium in G. capitata is very long, and bears four
minute tentacles at its tip, and a pair of minute palps at its
base. There are no gills. The dorsal cirrus is reduced to a
mere knob, and the. ventral is small.
Fam. Arenicolidse.
Arenicola. In A. piscatorum there are thirteen pairs of gills, and
a gill-less tail region behind these.
Fam. Spionidse.
Nerine. In N. coniocephala the prostomium is conical, in N.
vulgaris it is T-shaped.
Fam. Cirratulidae.
Cirratulus. In 0. cirratus a transverse row of tentacular filaments
occurs immediately behind the head. The gills are present
chiefly in the anterior region.
Fam. Terebellidse.
Terebella. In T. conchilega there are three pairs of gills placed on
segments two to four, and fourteen to seventeen pairs of red
gland-shields on the under surface.
Fam. Amphictenidse.
Pectinaria. In P. belgica the tube is straight. There are two
pairs of gills.
Fam. Chlorhsemidse.
Trophonia. In T. plumosa, there are two long tentacles and eight
short gills on the head, which is inclosed in a "cage"
of bristles.
Fam. Sabellidse.
Dasychone. In D. bombyx the back of the gill -filaments bears
distinct dark-coloured eyes.
Fam. Serpulidoe.
Pomatoceros. In P. triqueter the operculum is limy, and bears at
the sides two horny processes.
NOTE ON DISTRIBUTION.
Perhaps one of the most striking points in regard to the distribution
of the worms mentioned is the great size and abundance of Nereis
pelagica on the North-east, and its comparative rarity and small size
on the South and West. On the other hand, Nereis dumerilii is much
larger on the West Coast than on the East, and is apparently more
abundant on the former coast. The Sabellids are perhaps commoner
between tide-marks on the South and West. Generally, however,
the worms mentioned are widely distributed round our coasts, subject
to local variation dependent on food-supply, suitable localities, and
so on.
CHAPTER VII.
SEA-URCHINS, STARFISH, AND BRITTLE-STARS.
General characters of common starfish — The characters of Echino-
derms and the classes— The starfishes ami their colour varieties
— The brittle-stars and their peculiarities of structure — The sand-
stars — Methods of preserving starfish and brittle-stars — The sea-
urchins — Characters of regular urchins— Structure of the shell —
Internal anatomy— The heart-urchin, its habitat and structure —
Contrast with regular urchins — The Holothurians— Cucumaria and
Synapta — Development of Echinoderms.
IN the present chapter we shall be concerned with a very
interesting group of animals which are singularly well
defined, and not closely related to any others. Some of the
general characters of the Echinoderms have already been
noticed, others will appear during the course of a prelimi-
nary examination of the common starfish, or five-finger.
This is to be found in abundance on the shore, especially
in the vicinity of mussel beds. It feeds on bivalves of
various kinds, and does great damage to mussel and oyster
beds. In the neighbourhood of these it grows to a great
size, specimens measuring a foot from tip to tip of opposite
rays not being uncommon; but on the shore rocks, away
from such an extensive food-supply, the usual size is much
less. In collecting specimens for examination, you are
certain, sooner or later, to encounter individuals strikingly
different from the normal. They may have one large ray
and four small, or any combination of small and large rays.
These illustrate one of the striking peculiarities of the
Echinoderms — their capacity for regenerating lost parts.
In many cases, notably in the brittle-stars, the animals
throw off portions of their bodies when attacked ; in other
cases, though the animals do not practise self-mutilation to
125
126 LIFE BY THE SEASHORE.
any extent, they possess an extraordinary power of repair-
ing accidental injuries.
Having collected some specimens of the common starfish
and placed them in sea-water, the external characteristics
can be readily made out. The fact that there are five rays
is very obvious, as is also the prickly skin, the ventral
mouth, and the five grooves which radiate from the mouth
and contain the transparent tube-feet. When the starfish
is lifted up from the surface to which it is adhering, it will
be noticed that it is attached to this surface by the tube-
feet, which end in suckers. So firmly do the suckers cling
that it often happens that when the animal is removed from
the rock, some of the tube-feet break through rather than
let go. When the animal is held in the hand it is easy to
feel the limy plates in the skin, and a dried skeletonised
specimen picked from the beach will show you the beautiful
arrangement of ossicles, or limy plates, which bound the
ventral groove along which the tube-feet lie. On the dorsal
surface notice between two of the rays a white plate, called
the madreporite, or rose-plate, which is perforated by numer-
ous holes through which the sea-water enters the system of
canals which supplies the tube-feet. These become tense
or flaccid according to the amount of fluid they contain, and
being alternately fixed and loosened, serve not only for
attachment to rock surfaces, but also for leisurely pro-
gression. This may occur in any direction, for the starfish
being radially symmetrical like a flower, or a sea-anemone,
has no head — no specialised region which always moves
foremost. The radial symmetry (usually based on the num-
ber five), the limy skin, the peculiar tube-feet, which are
part of the "water-vascular" system, the power of re-
generation and frequently of self-mutilation, comprise the
most obvious of the external characters of the Echinoderms.
There are five living classes : —
1. Starfishes (Asteroids).
2. Brittle-stars (Ophiuroids).
3. Sea-urchins (Echinoids).
4. Sea-lilies (Crinoids).
5. Sea-cucumbers (Holothurians).
But of these the sea-lilies only occur in deep water, mostly
SEA-URCHINS, STARFISH, AND BRITTLE-STARS 127
only in the great depths, and the sea-cucumbers are rare
between tide-marks, at least on the East Coast; so that
practically our studies of the group must be confined to the
starfishes, brittle-stars, and sea-urchins. Even of these we
have very few littoral species, so there should be no diffi-
culty in learning to recognise all the common forms. We
may conveniently begin with the starfishes, in which the
body is distinctly star-shaped, but has often more than five
arms, has an open ambulacral groove (or groove containing
the tube-feet) on the ventral surface of each arm, or ray,
and has both the digestive and the reproductive organs pro-
longed into the stout arms.
The common starfish, Asterias rubens, is perhaps the most
abundant form, and we may describe its peculiarities first.
As in most shore Echinoderms the colour is very variable — •
red, orange, purple being the commonest tints. The limy
plates in the skin are netted, or reticulate, and bear numerous
small spines. A row of these spines runs down the middle
of each arm, but in very large specimens this regularity of
arrangement is not obvious near the ends of the rays.
Scattered among the spines are pedicellarice, or little stalked
forceps. The tube-feet are arranged in four rows, and the
sides of the ambulacral groove are furnished with two rows
of spines. To the outer sides of these spines there are
three rows of closely crowded spines. We have already
noticed the frequent occurrence of specimens showing re-
generation of lost or injured parts. In some places this
starfish is extraordinarily common, and occurs in numbers
in every rocky crevice. St. Andrews and Joppa may be
specially mentioned as spots where I have found it very
abundant. On the West Coast there occurs, in addition,
the larger and handsomer Asterias gladalis, which has
larger and more numerous spines, arranged in several regular
rows down the arms ; but this does not occur on the East.
Almost equally common with Asterias rubens is another
smaller five-rayed starfish which occurs in many colour
varieties — purple, purplish red, pure red, orange, all being
common. It is more compact in shape than the common
starfish, and contains so much lime that it is exceedingly stiff
and does not droop flaccidly when lifted up as that animal
does. This is Henricia sanguinolenta, and it has also a
128
LIFE BY THE SEASHOKE.
distinctly reticulate or netted skeleton, with minute spines
on the meshes of the net. Between the meshes there are
in some places pores through which little sacs, or skin-gills,
can be protruded. The rays taper very gradually, and have
a very narrow ventral groove with two rows of tube-feet.
At the sides of the groove there are dense rows of small
spines. The species is interesting because it extends over a
very wide area, not only horizontally but also vertically; for
it lives from the shore down to great depths. About two to
four inches from ray to ray may be given as a common size
for shore specimens, though the animal does grow to a much
larger size. It is very variable, varying greatly not only as
to colour, but also as to the degree of development of the
spines, and even the number of rays. It is not uncommon
to find four- or six-rayed specimens, though normally the
number is five.
Our list of littoral starfishes is so short that when we
have named the sun-star (Solaster papposus, see Fig. 41),
we have named all
that are likely to
occur in the living
state between tide-
marks on the East
Coast. Our common
sun-star reaches a
large size, and may
be recognised by the
fact that it has twelve
or more rays. Like
so many starfishes,
it varies greatly in
colour — usually pur-
plish red blotched
with white, it is
sometimes pure red,
and sometimes
orange. The dorsal
surface is covered with peculiar spines of large size, which
are separated by spaces through which the little skin-gills
emerge in life. Each of these dorsal spines consists of a
pillar, bearing at its top a cluster of crowded spines, pro-
Fio. 41. — Solaster papposus, or sun-star. Note the
round madreporite to the left of the central disc.
SEA-URCHINS, STARFISH, AND BRITTLE-STARS.
129
ducing the appearance of a little brush. At the sides of
the short rays there are prominent lateral spines of simple
structure. There can be no difficulty in recognising the
sun-star, but it is interesting to notice how it differs from
another species, Solaster endeca, which is sometimes flung
on the beach by storms. This has nine to eleven arms, is
usually purple, not purplish red, has more numerous dorsal
spines more closely packed together, and less distinct lateral
spines.
After the starfishes we come to the Ophiuroids, or brittle-
stars, which from their shape and habits are perhaps less
conspicuous than
the starfishes, but
are quite as abund-
ant. They are to
be found under
stones or among
weed, twining
their, long snaky
arms about the
surrounding ob-
jects, and snap-
ping them off at
a touch. At least
three species are
common in the
living condition
between tide-
marks, and others
occur at times after storms. Instead of giving a formal
definition of the group, let us look at the general charac-
ters of our common brittle-star (Ophiothrix fragilis, see
Fig. 42). It is especially abundant among the roots of
oar- weed, and a few specimens should be extricated with
care and put into clean water. Notice first the much
greater activity than that displayed by starfish ; it is often
difficult to say whether a specimen of the latter is alive or
dead, so limp and flaccid does it appear even when taken
fresh from its pool. The brittle-star, on the other hand, is
continually wriggling its arms, and can progress rapidly by
their means at a rate which has been estimated at about
FIG. 42.— Common brittle-star (OphiotJirix fragilis).
r, radial shield ; sp, spines.
130
LIFE BY THE SEASHORE.
twenty times that attained by the common starfish. The
arms, or rays, are very long and slender, so slender that
there is no difficulty in realising that they do not, like
those of the starfish, contain prolongations of the digestive
organs, which here, like the reproductive organs, are con-
fined to the disc. The tube-feet are also reduced, are no
longer placed in an open ambulacral groove, are not used
in locomotion, and are small and tentacle-like in appearance.
Between the rays there are peculiar bursse (b in Fig. 43), or
pockets, which open to
the exterior by deep
slits placed at the sides
jof the rays. These are
breathing organs, and
are very characteristic
of brittle -stars.
This general survey
of a brittle-star should
make the main points of
contrast with starfish
clear, but the details of
structure are difficult ;
we can only indicate the
more important points.
FIG. 43.— Diagrammatic view of the under First, as to the ravs :
surface of the disc in the sand-star , , -i • i •
(Ophiura). Of the five rays three are cut among the dried Wreck-
short close to the disc, the other two just OCTP npnr Vn'rrh rirlp •mirL-
beyond its limits. In the centre is the star- a§6 near HlgH-tlde mark,
like mouth; the tiiangular plates which yOU Will always find
project into it are fringed by mouth- olrolafnTn'onrl V.™ffl« of^-r,
papillae. The presence of teeth is also Skeletonised brittle-stars
indicated. ft, one of the bursal slits ; ms, which will show that
one of the mouth-shields; s. arm-spines. ,1 ,
the arms are made up
of a series of segments or vertebrae, jointed together. Out-
side these segments there are a series of plates, one of
which is placed on the dorsal surface of each segment, one
on the ventral, and two at the sides. These last, the lateral,
plates bear spines. The delicate tube-feet emerge at the
side of the rays, and there are one or two little plates,
called the tentacle scales, at the point of exit. In regard
to the disc the dorsal surface is variously marked in the
different species, but there are usually two distinct plates,
called radial shields, at the origin of each ray. On the
SEA-URCHINS, STARFISH, AND BRITTLE-STARS. 131
ventral surface we have the mouth, which has a complicated
structure. The main points are indicated in Fig. 43, which
is a diagram of the parts in the sand-star (Ophiurd). The
actual mouth -opening is small, for from its margin five
triangular projections jut inwards, the apex of the triangles
being towards the centre. These projections arise be-
tween the arms, and as they do not touch one another,
the mouth-cavity consists of a small central space con-
tinued into five slits, the slits corresponding to the rays.
Into these slit-like spaces the first tube-feet of each ray
project, and function as tentacles. The minute structure
of the triangular projections is of some importance in
identifying species. Each consists of a basal plate, or
mouth-shield, and two lateral plates in contact through-
out the whole or part of their length. In some cases these
lateral plates bear small spines at their edges, so that the
mouth-clefts are fringed by spines. Such spines are called
mouth-papillae. Again, spines may be present at the apex
of the triangle, such spines being called tooth -papillae.
Finally, beneath the tooth-papillae, and within the mouth-
cavity, there may be smaller spines called teeth. The
madreporite in brittle-stars is on the ventral surface, and
not the dorsal as in starfish, and replaces one of the mouth-
shields.
The common brittle-star (Opliiothrix fragilis), which in
most places is very common, is to be found under stones
and among tangles between tide-marks. Fair-sized speci-
mens measure three to four inches from tip to tip, but the
arms are very brittle, and break off at very slight provo-
cation. The colours are bright and variable, the rays being
usually banded, and the disc of a contrasting colour. Keds,
browns, and yellows are common tints, but the rays are
frequently violet or grey. The arms are flattened, and the
most characteristic point is the presence of long notched
glassy spines borne at the sides of the arms in bunches of
seven. Some other more minute points of structure may
be given as follows. There are no mouth-papillae, so that
the sides of mouth-clefts are unnotched, but there are
numerous tooth-papillae and teeth. On the dorsal surface
of the disc the radial shields are very conspicuous, but the
rest of the disc shows much variation in the presence or
132 LIFE BY THE SEASHORE.
absence of spines. The whole animal, indeed, shows much
variation, and it is so common that it is interesting to study
the variation in detail for any locality.
Almost as abundant as the common brittle-star is the
daisy brittle-star, which occurs in similar localities. The
differences between the two are not very easily described,
though an examination of actual specimens should make
them obvious enough. Perhaps the most obvious difference
is in the spines, which in the "daisy" are short and stout.
The arms themselves are wide and flat, less fragile, and not
so long as in Ophiotlirixfragilis. They are usually beautifully
banded with alternate bars of red and white. There is no
difficulty in learning to distinguish these two common
brittle-stars by what may be described as mere "rule of
thumb," but those who care to make their knowledge exact
may welcome a brief account of the more minute peculiarities
of the " daisy." Its scientific name is Opliiopholis aculeata,
and among its notable characteristics are the fact that the
upper arm plates are surrounded by small additional plates,
that the disc is so covered by granules that the radial
plates are rendered obscure, and that while teeth-papillse
are absgnt, three mouth-papillae are present at each side of
the mouth-clefts. The spines borne by the lateral arm
plates are seven in number, and, as already stated, are short
and stout.
Both the common and the daisy brittle-stars live fairly
well in confinement, especially in the case of small specimens,
and they are well worth the careful study which can be
most readily bestowed on captive specimens. Like other
brittle-stars, they are somewhat difficult to study and to
name, both on account of the complexity of their hard
parts, and of the great colour variability. As regards the
question of naming your specimens, one hint may be given,
though it is one the beginner is apt to resent — it is, do not
forget to look at your specimens before you try to name
them. Very many people who are interested in natural
objects begin systematic work with British flowering plants,
and are then apt to acquire the pernicious habit of naming
specimens by what one may describe as a mere trick — the
shape of the petals, or of the fruit, or some other single
point. The educative value of species work, however,
SEA-URCHINS, STARFISH, AND BRITTLE-STARS. 133
certainly in the case of animals at least, is its training in
the perception of form, and one should strive to learn not
merely to count or measure spines, but to perceive those
real differences of form which are often so difficult to
explain in words, but which constitute the true distinctions
between species. The brittle-stars are especially adapted
for exercises of this kind, and before you begin to study
the minute details of structure, you should strive to acquire
an exact knowledge of the general form. It is an interesting
if somewhat humiliating experience to look at a brittle-star
for a few minutes, then to cover it up and endeavour either
to draw or to even merely visualise the specimen, and then
compare your mental image or your sketch with the real
object. Both generally leave much to be desired in the way
of precision.
There are a considerable number of other brittle-stars, or
sand-stars, which may occur between tide-marks, especially
after storms. One which occurs there freely in the living
condition, but is liable to be overlooked on account of its
small size, is Amphiura elegans. It should be looked for
under stones, and does not usually exceed one inch to one
and a half inches in length. The colours are sober and
inconspicuous, and the creature may be recognised by its
round disc with well-marked radial shields, and the slender
arms whose side plates bear three to four inconspicuous
spines. There are three mouth-papillae on either side of
the mouth-clefts. After storms, or among the wreckage at
most seasons of the year, the common sand-stars Ophiura
lacertosa and 0. alUda are to be found. They can be
recognised by the fact that the disc is cleft at the origin of
the arms, the clefts being fringed by papillae. In the larger,
0. lacertosa, these papillae are ten to twelve in number,
while in the smaller, 0. albida, they number about thirty.
The arms bear only minute spines, which are so closely
adpressed to the sides of the arms that they are not seen on
casual view. The disc is completely covered with scales.
The sand-stars occur perhaps most frequently in the
skeletonised condition, high up on the shore, and are then
admirable subjects for the study of the Ophiuroid skeleton
(see Fig. 43).
The Ophiuroids in general offer many interesting points
134 LIFE BY THE SEASHOEE.
of contrast with the starfishes. While in the latter it is
common to find that the arms exceed five in number, in the
Ophiuroids this is not the case. As the name brittle-star
indicates, the Ophiuroids are generally very fragile, but the
somewhat rare starfish Luidia shows that the same fragility
may occur in the Asteroids. Indeed, though our British
Asteroids and Ophiuroids are sharply marked off from one
another, when the groups are considered as a whole their
close relation becomes obvious.
On account of the large amount of lime in the tissues,
the starfishes and some of the Ophiuroids make good dry
preparations, and are often most easily preserved in this
way. In the case of the larger starfish it is desirable to
remove some of the water from the tissues before allowing
the specimens to dry. This is best accomplished by placing
the animal in spirit for twenty-four hours, changing the
spirit once during that time. This "dehydrating" process
may be conveniently carried out in a pie-dish covered by a
plate. Afterwards the starfish should be lifted out and
allowed to dry slowly in air ; a well-ventilated outhouse, or,
in default of it, a shady window-ledge, is a good situation
for the process. The dried specimens should be kept in a
cabinet with camphor or some other preservative against the
attacks of insects; if they become damp, or show signs of
" going wrong " in any way, a repetition of the dehydrating
and drying process is often effective. In the case of the
brittle-stars, the prime difficulty is usually to obtain a
perfect specimen either to dry or to preserve, for the animals
usually break up in dying. In some cases at least specimens
may be instantly killed without rupture by dropping them
suddenly into boiling water, and as death is practically
instantaneous, the objection of the apparent cruelty need
hardly be entertained— apart from the other debated
question how much a brainless animal like an Ophiuroid
can really "feel." Specimens killed in this way become
abnormally brittle after death, and must be handled with
extreme caution.
The next set of Echinoderms is constituted by the sea-
urchins, which have this advantage over the brittle-stars
that they are more or less familiar to everyone. To study
the general characters you should provide yourself with a
SEA-URCHINS, STARFISH, AND BRITTLE-STARS. 135
good number of the empty shells, or tests, which usually
ornament cottage windows near the sea, and are to be found
on the beach at most seasons of the year. In addition, an
attempt should be made to obtain one or two living
specimens. It is not always easy to obtain the common
urchin (Echinus esculentus) in the living condition, but the
small purple-tipped urchin (E. miliaris) may generally be
found in the Laminarian zone, and has the advantage that
one may keep it alive in confinement longer than its relative,
which needs a great bulk of water.
Let us examine the living specimens first. The common
urchin is really an inhabitant of fairly deep water, but I
have often taken single 'specimens at low spring tides, and
where the shore slopes steeply the urchins may sometimes
be seen in numbers by looking over the edge of the rocks.
The colour is usually purplish pink, but I have found
specimens entirely straw coloured, with beautiful purple
tube-feet. The test is rounded, and in life covered by
numerous long spines. In E. miliaris, which is very much
smaller, the diameter often not exceeding that of a penny,
the test is flattened, and the numerous spines are short and
not of uniform size. The general tint is green, but the
spines are tipped with purple. In either urchin you will
notice the mouth in the middle of the under surface. It is
surrounded by a membrane which is very extensile, so that
the mouth can be protruded to a considerable extent, and
then withdrawn. The object of this, as a living active
urchin will show, is to allow of the free movement of a
complicated tooth-bearing structure called Aristotle's lantern.
This contains a circle of five chisel-edged teeth (see Fig. 44)
which may be seen and felt in the mouth of the urchin, and
are borne by an arrangement of ossicles, which permit the
teeth to open and close so that the urchin can crop seaweed
as effectually as a rabbit crops dandelions. Their action is
greatly aided by the elastic mouth membrane, which is
covered by small tube-feet which act as tentacles, and by
little stalked forceps called pedicellarias, curious structures
common among the Echinoderms, and probably serving to
keep the test clean.
The presence of this mouth-membrane and of Aristotle's
lantern has a rather interesting effect in the case of dried
136 LIFE BY THE SEASHORE.
specimens. If you have a fair collection of these, you will
probably find among them some which present much the same
appearance as the living specimens, spines, mouth-membrane,
and teeth all being present as usual. In not a few cases, how-
ever, you will notice that the soft membrane shows signs of
decay — either it cracks in dying, or it is attacked by sand-
hoppers or some of the shore insects. The result is to set
free the bulky and heavy lantern. This may then simply
fall out of the empty test, and be found lying intact on the
sand, or more probably its ligaments speedily decay and one
finds merely the scattered ossicles and teeth among the
wreckage. By the decay of the membrane the cavity of
the urchin is fully exposed, and the soft parts are speedily
FIG. 44. —Portions of Aristotle's lantern from a sea-urchin,
a, external view of the lantern, showing two of the five main
pieces (alveoli) of which it is composed ; b, internal view of
single piece ; c, side view ; t, in each figure, one of the five
chisel-edged teeth, which run through the alveoli and are
carried by them.
eaten up, or dried up by the sun. The test then becomes
very light, is rolled over and over by the waves, so that the
spines are removed, and there is left the familiar empty
shell with a gaping orifice beneath, and a surface covered by
white knobs which show the places where the spines were
formerly attached. In other cases the disintegration of the
membrane is only partial, and the lantern merely falls into
the cavity of the urchin. Specimens of this kind often
occur with the lantern loose inside, and rattling at every
movement. As the lantern is heavy, the result in this case
is often to break the test in pieces, when the separated
waterworn pieces appear on the shore as what children call
"sailor's cheese."
After this digression we may return to our living urchin.
SEA-URCHINS, STARFISH, AND BRITTLE-STARS. 137
More obvious than mouth and teeth are usually the long
slender tube-feet, which form five double bands over the
test, and can be stretched out to a great length. They,
indeed, give the sea-urchin a great part of its beauty, and in
life are in constant movement, now extended, now con-
tracted. By this means the sea-urchin is enabled to crawl
up a perpendicular surface. The only other point which
can be readily observed in the living urchin is the posterior
opening of the food canal at the point opposite to the mouth.
It is surrounded by small plates of lime, and, as these are
readily removed, is in consequence often represented by a
large hole in dried specimens.
To study the composition of the urchin's test in detail we
must return to the dried specimens from which the spines
have been rubbed off. As already noticed, the mouth is
usually now represented only by a gaping hole, by which
the lantern has been shaken out. The anus may or may
not have lost its small plates, but around it will be seen ten
distinct plates, which mark out as many radii on the shell.
Five of these plates bear each a distinct round hole, which
is the opening of the reproductive duct, but one of the five
is in addition perforated by minute holes, and so constitutes
the madreporite. The other five plates are smaller, and
bear each an eye-spot. In a line with these five plates
are the five ambulacral areas of the test, which each
consist of two rows of plates perforated by the minute
pores through which the tube-feet emerge. In addition
these plates, which are relatively narrow, bear a few spines.
Corresponding to the larger plates, and thus alternating
with the ambulacral areas, are five interambulacral areas,
each consisting of a double row of wide plates, bearing
numerous spines. The net result is to produce in the living
urchin five double rows of tube-feet, separated from each
other by a somewhat wide interval thickly covered with
spines. The spines have a curious ball-and-socket joint at
the base, and are very freely movable. They assist in
locomotion, and must also protect the test from mechani-
cal injury. The large urchin lives freely exposed, and
probably from its strong armour has little to fear from
the attacks of enemies ; but the little purple-tipped urchin
covers itself with weed and fragments of stone and shell as
138
LIFE BY THE SEASHORE.
though to seek protection. It is in consequence not very
easily seen except by careful search, but is common enough
in the Laminarian zone. The depressed shape and green
and purple colour make it easily recognised. As already
indicated, the common urchin only occurs somewhat sporadi-
cally between tide-marks, but it is at times thrown on shore
in great numbers after gales, and is generally to be found
in the dry condition on the beach. The diet of both
urchins seems to vary, probably in part according to the
locality; in many places both live largely on seaweed, but
are not averse to mingling this with animal matter.
In both cases
the internal anat-
omy is very in-
teresting, and a
general notion of
its main outlines
is easily obtained.
With a strong
pair of scissors
make a circular
incision midway
between mouth
and anus, and then
lift off the upper
segment. In it
FIG. 45. — Echinus esculentus. common sea-urchin. The nr>p «PPQ flip fiva
r' ies have been removed from half the test, to u /& .MM
w the structure of the latter. The reference reproductive or-
lines (a) inclose an ambulacral area; i is an inter- vowin^
ambulacral area. &clllb> Vclljlli5
greatly in size ac-
cording to the season of the year; in the lower we see
Aristotle's lantern, which is very large relatively to the
size of the animal, and is perforated by the brown ali-
mentary canal, which, after leaving the lantern, coils about
the shell, and ultimately passes upwards to end at the
anus. Notice also the stone canal, a tube hanging verti-
cally from the madreporite, which opens into a ring canal
placed on the lantern, which again opens into five radial
canals running along the inner side of the ambulacral
areas. Each radial canal communicates by lateral branches
with the tube -feet, and with the leaf -like ampullw
SEA-URCHINS, STARFISH, AND BRITTLE-STARS. 139
which lie on the inner side of the shell, and form very
conspicuous objects. Perhaps, however, in the common
urchin at least, you will be most struck by the apparent
emptiness of the shell. It contains a large amount of
watery perivisceral fluid, but even when the urchin is fully
ripe seems disproportionately large relatively to the con-
tained organs. It should be noticed that the shell is not
an external structure like the coat of a crab, for its outer
surface is covered by a thin layer of skin, and in develop-
ment it arises as an internal skeleton. The separate plates
of which it is composed go on growing during life, and in
this way the whole test increases in size as the urchin
grows older.
These two urchins are the commonest of our regular
urchins, which are characterised by their more or less
spherical shape and the regular arrangement of their tube-
feet in five double rows. The majority of the internal
organs, reproductive organs, nerves, ambulacral canals, etc.,
occur in fives; or, in other words, the symmetry is penta-
merous throughout. It is otherwise with the next urchin
to be considered, which has a less well developed ambulacral
system, and shows a tendency to lose this five-rayed symmetry
in favour of a bilateral arrangement. There are a number
of such irregular urchins, but the commonest is perhaps
Ecliinocardium cordatum, which shares with some of its
allies the popular name of heart-urchin. The heart-urchins
are most interesting animals, interesting both in themselves
and in their contrast with the common urchins. To get
Echinocardium in the living state one must be prepared to
risk a good deal in the way of wet feet. If the enthusiasm
of the naturalist rises above this objection, the next desi-
deratum is a strong spade — not a toy, but the genuine
article borrowed from the gardener — and a good low spring
tide. The last is in most cases essential. Then choose a
spot where the tide ebbs a long distance over sand which is
shown, by abundant worm-castings and mollusc shells, to be
suited to animal life, and begin work at the margin of the
water. It may be well to repeat warnings already given as
to the force of spring tides and the possible element of
danger in shore hunting at that period. In most cases the
tide rushes in over those long level flats, beloved of sand-
140 . LIFE BY THE SEASHOEE.
dwellers, with great rapidity, and the enthusiastic naturalist
is often wise to take with him a cautious and unenthusiastic
companion and a flat-bottomed boat. He will soon learn by
experience whether the element of safety imparted by the
presence of the boat compensates for the trouble of wading
for perhaps half a mile through water too shallow for it to
move or laboriously pushing it over the sandy flats. All
these are mere trifles to the genuine enthusiast, and if the
ground be rich, sand digging becomes a delightful and profit-
able amusement. You may get many curious creatures, but
there is at least this satisfaction in regard to the heart-
urchins, that if you find any at all you are pretty sure to
find as many as you can possibly want. They occur at no
great depth below the surface, in burrows of their own
making, and many are at times turned up in each spadeful
of sand. In life they are of a beautiful golden colour,
which unfortunately speedily fades after death, and the tests
are so fragile that they are often broken to pieces in the
mere handling and separating from the sand.
As regards structure, notice first the silky spines, which
vary much in size, and are not uniformly distributed over
the surface. The test is somewhat heart-shaped, and flattened
beneath, and the mouth will be found on this lower flattened
surface, overhung by a lip-like process, but without any
trace of a lantern. Round the mouth, and sending two
diverging horns backwards, is a bare space, perforated,
especially near the mouth, by pores through which a few
tube-feet emerge. These are somewhat complicated in
structure, having curious brush-shaped tips, and function as
tentacles. Between the posterior diverging horns just men-
tioned is a group of interesting spines. They are stout and
flattened at the ends, or spatulate. It is these which are
used in excavating the burrow, their action being assisted
by the other spines, which have an interesting and somewhat
complicated arrangement, well worth careful study, and by
the mouth process. Next turn over your specimen and
study the dorsal surface. In a living specimen it is possible
to make out, though less clearly than in the dry shell, that
the ambulacral areas in this region show what is called a
petaloid arrangement, that is, they are arranged roughly
speaking in the form of a five-rayed star, and are thus
SEA-URCHINS, STARFISH, AND BRITTLE-STARS. 141
something like a flower. The odd ray is to the front, and is
more conspicuous than the others because it is placed in a
deep groove. On the sides of this groove there are rows of
spines bent inwards until they nearly meet. Place a living
specimen before you with the grooved region towards you,
and you will notice that the slope of the test, the position
of the groove, and the arrangement of the spines, are all so
adjusted as to form a definite canal, which leads from the
crest of the shell straight towards the mouth with its spout-
like process. Notice also that the tube-feet of the petaloid
area are extensile and well developed, and so arranged as to
serve to catch hold of food-particles and sweep them down-
wards into the groove and so to the mouth. Notice the
anus near the middle of the vertical posterior region of the
shell, and the peculiar rounded sub-anal area beneath it,
which is liable to be mistaken for it. You will also notice,
what is even more obvious in dissection, that the apertures
of mouth and anus are very small indeed, showing that the
animal cannot live upon particles of considerable size, as do
the regular urchins.
Having made these observations on the external aspect
of the living animal, you may proceed to study some of the
details of anatomy. To do this you should provide yourself
both with fresh specimens and with a considerable number
of dried tests, in the condition in which they are to be
found on every sandy beach. Dissection in the strict sense
is of course impossible; but a good idea of the anatomy
may be obtained by cutting open the shells with a strong
pair of scissors in different directions, so as to get different
views of the interior.
Let us consider first the function of nutrition. What
does the heart-urchin feed upon? The first one you open
will show, even if you had not previously come to con-
clusions on the subject from the habitat. It feeds on the
minute particles contained in sand, and the alimentary canal
is always filled with sand, which is swept into the mouth
down the groove in the way of which we have already
spoken. As sand is abundant, the urchin does not need
to go and seek its food, but remains more or less passively
within its burrow, and uses its tube -feet and spines in
directing the food-supplies to the mouth. The food requires
142 LIFE BY THE SEASHORE.
no mastication, and so we find that the lantern and its
supports have disappeared. The position of the anus at
the posterior end, instead of at the top of the shell as in
EC) Linus } is probably an adaptation to life in a burrow ; for
as the urchin's food to a large extent must come from
above, it is desirable that waste material should not be
deposited where it might mingle again with the food.
What effect has this more or less sedentary life had upon
the ambulacral system ? In the first place it is obvious that
this has at least very largely lost its locomotor functions.
The feet have now no suckers; they are not, as in the
common urchin, arranged so as to make locomotion in every
direction possible, and indeed the shape of the test would
render this impossible in any case. The tube-feet now act
largely as tentacles, and also possess, as in the regular
urchins, some respiratory function. We have noticed that
they seem not to be continuous over the whole test, but
form a petaloid area on the dorsal surface, and a similar
but less well developed area about the mouth on the ventral
surface. Careful examination of the interior will, however,
show you that the radial canals are continuous internally,
and that the upper and lower petaloid areas are connected
by regions in which a few small scattered tube-feet occur.
In the dry shell on the dorsal surface, to the posterior side
of four pores which you will find near the upper end of
the groove, you will be able with the aid of a lens to
discover the madreporite, or rose-plate, which has remained
in its primitive position, while the anus has moved back-
wards. Thus we see that the ambulacral system is con-
structed on the same plan in Echinocardium as in Echinus ;
but in the former certain of the tube-feet have, as it were,
been accentuated, at the expense of others which are now
only very slightly developed. It is interesting to note
that the irregularity which manifests itself in the external
appearance of the urchin is also apparent internally in the
reproductive organs, of which there are now four only
instead of five. The four pores spoken of above are the
four genital pores (cf. the five of Echinus).
This description of Echinocardium will not be found very
readily intelligible unless it is studied with the help of
actual specimens, but dried specimens at least are so extra-
!
SEA-URCHINS, STARFISH, AND BRITTLE-STARS. 143
ordinarily plentiful that there is no reason why this should
not be done. The contrast between the regular urchins
with their strong shells, uniform coating of spines, and
well-developed tube-feet, and the heart-urchins with their
fragile shells, on which both spines and tube-feet are dis-
tributed in so complex a fashion, and which have lost the
primitive radiate symmetry, is so striking, and so intimately
related to the different modes of life, that it is worth
careful study. A great part of the interest attached to
the Echinoderma is due to the fact that the members of
the group show adaptations to many different kinds of life,
while retaining those well-defined characters which make
the group such a compact one. In many cases the structural
adaptations to particular habitats are difficult to study, but
in the heart-urchins they are fairly obvious, and intensely
interesting. Between tide-marks EcTiinocardium cordatum
is the only heart-urchin likely to be found in the living
condition ; but on the beach after storms one at times finds
the purple heart-urchin (Spatangus purpureus). The differ-
ences between it and Echinocardinm are not very striking
apart from colour. The most noticeable difference is perhaps
the fact that in Spatangus certain of the spines are very
long, strong, and curved — a difference probably associated
with the fact that the animal lives in coarser material
(coarse sand or gravel) than Ediinocardium.
The next group of Echinoderms — the Holothurians, or
sea-cucumbers — is very poorly represented on the East
Tloast, at any rate in shallow water, though, indeed, in any
case the majority occur beyond tide-marks. For the sake
of completeness we may describe a typical form, such as
Cucumaria ladea, which does occur between tide-marks
occasionally. It is a little creature, about an inch long,
with a cylindrical body, and a tough skin of white or brown
colour. The form is strikingly different from that of other
Echinoderms, for it is characteristic of the Holothurians
that their radial symmetry is not obvious, most of them
being of worm-like form, and showing more or less distinct
bilateral symmetry. If you obtain Cucumaria in the living
active condition, you will see it protrude at one end of the
body a beautiful crown of ten branched tentacles (te in
Fig. 46). At the other end of the body is the anus, and
144 LIFE BY THE SEASHORE.
between these two extremities there occur five zigzag rows
of tube-feet (tf in Fig. 46). These are very different from
the long, delicate tubes of a sea-urchin, for they are short,
stiff, and can only be very imperfectly retracted. The
skeleton, as in all Holothurians, is represented only by
deposits of lime in the skin, which are not continuous, and
are not at all conspicuous. The internal anatomy we need
not consider, but may only remark in passing that most
Holothurians have a distressing habit of throwing out
portions of their internal organs when attacked or alarmed.
In consequence one only rarely gets an intact specimen for
dissection; even those which seem uninjured will often be
found when opened to have lost some of the viscera.
tf
FIG. 46.— Sea-cucumber (Cucumaria planci). After Bell, tf, one of the five
rows of tube-feet ; te, tentacles surrounding the mouth.
There is one other Holothurian which occurs not un-
commonly all round our coasts, though it is not often seen.
If, however, you make that low-tide excursion to a sandy
beach which has been recommended as the only way of
getting Echinocardium in the living condition, you will
probably find among your spoil pink worm-like creatures,
which you are not unlikely to describe either as " worms,"
or as burrowing sea-anemones. They are slender, trans-
lucent creatures with an anterior crown of tentacles, and
are usually about three inches in length. If you examine
the surface of the body with a lens, and also pass your
finger over it, you will notice one of the most curious
characters of Synapta, as the little creature is called. This
is the presence in the skin of little anchors of lime, whose
SEA-URCHINS, STARFISH, AND BRITTLE -STARS. 145
flukes project from the surface and cling to the hand, as
under natural conditions they do to the sand. This Holo-
thurian, then, is literally and not metaphorically anchored to
the sand, the anchors being numerous and scattered all
over the body. If you examine a fragment of the skin
under a strong lens or a low power of the microscope, you
will see that each anchor is connected with a little plate
perforated by seven or nine holes, and that it can move
on this plate as on an axis. Plates and anchors together
represent the limy deposits of Cucumaria, and so the limy
skeleton of other Echinoderms, and are exceedingly character-
istic of Synapta. After having once been seen they can
hardly be mistaken for anything else. I once knew a
learned professor who was a great admirer of these anchors,
and used to bring them out with the utmost regularity
whenever he presided over a zoology examination. Both
they and their owner are a little out of the way of ordinary
zoology students' observations, so the candidates came to
grief time after time through their wild shots on the
subject, until the professor was ill-advised enough to remark
in a public address on the ignorance of Synapta which
prevailed among zoological students. After that all institu-
tions which sent up candidates to the public examinations
purchased a slide displaying the anchors, and so succeeded
in passing their students without the trouble of going to
dig for Synapta, or studying its structure.
Associated probably with the burrowing habit of Synapta,
we have the interesting fact that the tube-feet are absent
from the body, and are represented only by the crown of
tentacles at the anterior end. In Cucumaria the tentacles
are also modified tube-feet, and these are the only ones
which can be described as well developed. In Synapta the
tentacles are the only representatives of tube-feet present at
all. The statement that in Cucumaria and Synapta, as in
Holothurians in general, the tentacles are modified tube-feet
is not a mere assertion, but is justified by the relation of
these tentacles to the ambulacral system, a relation easily
studied in the larger Holothuria by dissection.
The only species of Synapta usually to be found between
tide-marks is S. inhcerens, recognised by its twelve tentacles,
each with six or seven finger-like processes at either side,
146 LIFE BY THE SEASHORE.
and by the fact that the edges of the holes of the anchor
plates are serrated. As is to be expected from the habitat,
it lives on the organic particles contained in sand, and the
alimentary canal with its contained sand can be seen shining
through the transparent body-wall. As in Cucumaria, the
tentacles can be completely retracted, and the animal is
then very worm-like in appearance.
This concludes the consideration of our common littoral
Echinoderms. The forms mentioned should give the student
a general idea of the main points of structure, and should
serve to indicate the general interest of the group. Our
common littoral forms are adapted to very various conditions
of life, and while retaining certain common peculiarities of
structure, present in a most interesting way what are known
as adaptive characters. One very interesting point in regard
to the group is, that the development is usually very
indirect, the larvae being quite unlike the adult, and adapted
for very different conditions. The larvae of our common
shore species are to be sought in the tow-net near the
surface of the sea, and are often very quaint in form. The
study of the development is beyond our scope, but this
chapter would be incomplete if it did not mention the fact
that not only are larvae and adults very unlike one another,
but that the former are converted into the latter by a
remarkable process of metamorphosis. Further, on account
of their marine habit, and the abundance of lime contained
in the tissues, the Echinoderms are abundantly represented
as fossils, and their geological history is in consequence
better known than that of most animals.
SEA-URCHINS, STARFISH, AND BRITTLE-STARS.
147
KEY FOR THE IDENTIFICATION OF THE SPECIES
DESCRIBED IN THIS CHAPTER.
Asterias
ECHINODERMA.
(1) The Asteroids, or Starfishes. Body star-shaped, with stout
arms containing prolongations of the digestive and reproductive organs,
and open anibulacral grooves.
'Spines small, nu-
merous, with
one row down
centre of arms
— A. nibens.
Spines large, not
very numerous,
arranged in
three to five
rows — A. gla-
cialis.
Anibulacral
groove narrow,
fringedbydense
rows of spines
— H. sanguino-
lenta.
Rays five, rarely
six
Tube-feet in four v
rows, skeleton
reticulate, its
small plates
bearing sim-
ple spines.
Pedicellarise
present
Tube-feet in two
rows, skeleton
reticulate,
meshes bear-
ing clusters of
small spines.
No pedicel-
larice
Henricia .
Rays more thanj
grooves fring-
ed by com
like spines
rRays 11 - 14,
colour red or
/Dorsal spines purplish red,
brush - like, dorsal spines in
tufts— S. pap-
Solaster . .1 posus.
Rays 9-11, colour
usually purple,
dorsal spines
much crowded
— S. endeca.
(2) The Ophiuroids, or Brittle-Stars. Body star-shaped, arms long
and slender without prolongations of the digestive or reproductive
organs ; no distinct anibulacral groove.
Nomouth-papil-\
1», arm spines f Arms fragile and
notched, ^G\.0nhiothrix \ long' sPines
with spines f •* 'j long and glassy
and distinct [ — 0. fragilis.
radials . ./
Tooth - papillae
(see p. 131)
present .
148
LIFE BY THE SEASHORE.
The Ophiuroidsj or Brittle-Stars.— continued.
rArms inserted
on ventral sur-
face; few-
^Spines on arms
stout, not long,
extra plates on
arms, which
are wide and
flat — Ophio-
pJwlis .
Three mouth -pa-
pillae, seven
spines at sides
of arms, radials
indistinct — 0.
aculeata.
No tooth-papil-
Ise, mouth-pa-,
pillae .present,
spines smooth
mouth - papil-
la}
Spines short and^
small, arms
long,discsmall
with distinct
radials — Am-
. phiura .
Three mouth-pa-
pillae, three or
- four fine spines
at sides of arms
— A. elegans.
Arm notches with
more than 25
Arms inserted 1 i i
_ . i spinose Dursai
spines — 0. cili-
aris.
rous mouth- 1 S extend to •
Arm notches with
rjamllse edge of disc
less than 20
\. uprtiura.
spines— 0. al-
bida.
(3) The Echinoids, or Sea-Urchins. Body more or less rounded,
covered by spines, test composed of plates arranged in regular rows.
/Test well rounded,
Body spherical, anus spines pinkish or
opposite mouth, five
regular double rows
of ambulacral plates,
Aristotle's lantern
present .
Body heart - shaped,
anus posterior, am-^
bulacral areas peta-
loid, no lantern
Echinus
white — E. escu-
lentus.
Test depressed, spines
purple-tipped — E.
miliaris.
c, . , ,, f [ Colour golden when
Spines and therefore fresh *nteriortube_
tubercles,nearlyequalj f |n ft ye._
-Echmocardium
Some spines, and there-
K Colour purple — S.
purpureus.
fore some tubercles,
larger than rest —
Spatangus . . -
(4) The Holothurians, or Sea-Cucumbers. Body more or less
elongated, without well-developed skeleton. Mouth with a fringe of
tentacles.
Tube - feetfTentacles ton,
present . ^ ed—Cucumana . .
JTentacleswithsimplelateranT d t d
Tube - feet! branchesordigits, anchors '
absent .| and^hor-plates present
,
SEA-URCHINS, STARFISH, AND BRITTLE-STARS. 149
NOTE ON DISTRIBUTION.
Generally speaking, the North Sea is poor in Echinoderms as
compared with other parts of our area, bub this is to some extent
compensated for by the great abundance of certain common species
on its shores. Thus, the common sun-star, Henricia sanguinolenta,
and the common starfish (Asterias rubens) are probably commoner
between tide-marks on the North-east Coast than on the South and
West. On parts of the South and West Coasts the spiny starfish
(Asterias glacialis) is to be found not uncommonly between tide-marks.
The brittle-stars mentioned are common everywhere, but on the South
the handsome yellow Ophiocoma nigra may also be expected between
tide-marks. In regard to the sea-urchins, those mentioned in the
text are widely distributed, but so far as my experience goes, Echinus
miliaris reaches a much larger size between tide-marks on the West
Coast than on the East. On the South and West sea-cucumbers are
much more likely to be found between tide-marks than on the East.
In addition to Cucumaria ladea, other species, such as G. pentades,
occur there.
CHAPTEE VIII.
THE DECAPOD CRUSTACEA.
General characters of Crustacea— Structure of prawn, lobster, and
crab— Classification of Decapod Crustacea— Swimming and creeping
forms — Common British shrimps and prawns.
IJS" this chapter we have to consider one of the most inter-
esting classes in the animal kingdom, interesting alike on
account of the beauty of form and colour, of the structure
and the habits. The class Crustacea is a very large one,
and embraces a great variety of animals adapted for many
different habitats and modes of life. Like the insects on
land, the Crustacea seem to display every possible modifica-
tion of parts; if they are less popular than insects it is
certainly not because they display fewer points of interest
or less beauty.
They resemble insects in being clothed in an envelope of
chitin, which invests the whole body, and is inturned to
line part of the alimentary canal and to form the tendons of
the muscles. This chitinous coat gives great definiteness
of form — the Crustacea never exhibit the variability of
shape which often makes the study of soft-skinned animals
so difficult; it has also such an intimate connection with
the internal organs that the external appearance may be
used as a test of affinity. In this respect the Crustacea,
or indeed the Arthropoda in general, differ markedly from
Molluscs. The shell of the latter has no very intimate
connection with the internal organs, it in itself yields little
information as to the anatomy of the contained animal.
In consequence, the structure and affinities of Molluscs can
be made out by dissection alone, and dissection, moreover,
which is often tedious and difficult even for trained fingers.
150
THE DECAPOD CRUSTACEA.
151
On the other hand, the structure of the external parts of a
Crustacean in the general case determines the systematic
position of the animal, and the examination of such external
parts requires more care than anatomical skill in the strict
sense. The Crustacea are therefore par excellence the class
for the novice, the one above all others in which he can
hope to walk by sight and not by faith.
In studying the Crustacea it is convenient to begin with
the higher forms, which are usually of such size as to make
observation easy. To acquire a general knowledge of the
structure, we may compare three common forms — a prawn,
a lobster, and a crab. The common prawn (Palcemon serratus),
a beautiful little creature about four inches long, is not likely
to be found on the East Coast, but a smaller species (P.
squilla) is not uncommon in rock pools, and is large enough
for our purpose. The hump-backed Esop prawn (Pandalus
annulicornis) may
also be found far
out on the rocks;
while, failing all
three, the common
shrimp may be sub-
stituted. As to the
second specimen,
the lobsters really
lie somewhat out-
side our province,
but the Norway
lobster (Nephrops
norvegicus) can be
purchased very cheaply at a fishmonger's, and is admirably
adapted for the study of many Crustacean characters. Those
who do not find it available will probably be able to obtain
the fresh-water crayfish, or that somewhat costly luxury
the true lobster. Add to your specimens the common shore
crab or the edible crab, and you are prepared for the study
of the characters of the Crustacea.
Place your three specimens — prawn or shrimp, lobster or
crayfish, and crab — side by side, and note first their common
characters. All three can be divided into two similar parts
by a line down the middle of the body — that is, all are
FIG. 47. — A common prawn (Palcemon squilla).
152 LIFE BY THE SEASHORE.
bilaterally symmetrical. All are invested with a firm
cuticle of chitin, are furnished with jointed hollow limbs,
and in each case the body consists of a series of similar
parts or segments, least obvious in the crab. Because of
these characters all are Arthropods. Further, we include
them in the class Crustacea because all have two pairs of
feelers (antennae), a shell containing carbonate of lime, and
all breathe by gills. The last-named structures may be
readily seen in prawn and lobster by gently raising the
FIG. 48.— Common lobster (Homarus vulgaris).
large flaps at the sides of the body in the anterior region.
Beneath these lie delicate structures, shaped like bottle-
brushes, and closely connected with the limbs. In the crab
the gills are so well protected by the shell as not to be seen
without dissection.
Looking now at our specimens in somewhat greater detail
we see that the prawn and lobster or crayfish resemble one
another in that in both the body consists of an anterior, not
THE DECAPOD CRUSTACEA. 153
obviously segmented region, covered by a shield, and a tail
made up of a succession of similar parts. The anterior
region we call the cephalothorax — for it is made of head and
thorax united — the posterior, the abdomen or tail. The
cephalothorax, or united head and body, contains the greater
part of the organs of the body ; the tail is mainly filled up
by powerful muscles (flesh), and in both prawn and lobster
serves as an organ of locomotion. The crab, on the other
hand, differs markedly from the other two in that it appears
to have no tail. Turn your crab over on its back, however,
and you will have no difficulty in seeing that it has really a
FIG. 49. — Shore crab (Carcinus mcenas).
true tail, reduced in size, useless for locomotion, without
muscles, and habitually carried reflexed on the body, but a
tail none the less. The body of the crab, no less than that
of prawn or lobster, consists of cephalothorax and abdomen,
but the proportions of the two parts differ markedly. In
consequence of this marked difference the order of Crustacea
to which the three forms belong (Decapoda, or forms with
ten legs) is often divided into long-tailed forms, such as
shrimp, prawn, and lobster, and short- tailed forms, such as
crabs.
Although there is considerable resemblance between
prawn and lobster as contrasted with crab, a little more
154 LIFE BY THE SEASHORE.
detailed observation will convince you that in some respects
the crab and lobster resemble one another closely and differ
from the prawn. Thus the body of the latter is laterally
compressed; its dorsal shield is prolonged forward into a
great beak, or rostrum, which is narrow from side to side ;
its ten legs are placed very near the mid-ventral line, and
are very slender as compared with the weight of the
body ; its powerful tail is furnished not only with tail fins,
but bears also five other pairs of well-developed oar-like
swimmerets. clearly shown in the figure. In brief, it is
essentially a swimming animal, capable of supporting itself
in mid-water by gentle rowing movements, or darting back-
wards by powerful tail strokes. On the other hand, in crab
and tobster the body is more or less compressed from above
downwards; the rostrum, when present, is broad from side
to side ; the legs are very well developed, and are divided
into an anterior pair of forceps, which are weapons of
offence and defence, and four pairs of walking legs, which
are not attached at the middle of the body, but at such a
position as to most readily support the weight of the
body. In the lobster the tail is a powerful organ, but the
swimmerets, except the last one, are not well developed.
In the crab, as already seen, the tail is greatly reduced.
In other words, crab and lobster are typically creeping
animals, adapted for life on the bottom. The lobster re-
tains, in addition, the power of swiftly darting backwards
by the flexing of the tail, and therefore retains also the
long feelers, movable exposed eyes, and some other charac-
ters in common with the prawn; but the crab can only
crawl, and is adapted throughout for life among stones and
weed.
If you have observed these points in your intact speci-
mens, then the next thing to be done is to take them to
pieces. Living specimens are best killed by dropping them
into very hot water for a few minutes. Of the three, the
Norway lobster, or crayfish, is the easiest to dissect. For
full details as to method, reference should be made to one
of the ordinary biological text-books, such as Marshall and
Hurst's Practical Zoology, or Thomson's Outlines of Zoology;
here we can only consider those points which are of im-
portance in our systematic survey.
THE DECAPOD CRUSTACEA. 155
Notice, first, that the shield, or carapace, is prolonged
forward between the eyes into the strong spiny beak, that
in its anterior region it has a strongly marked groove which
runs forwards to end near the outer side of the second pair
of antennae, or feelers, and that it is prolonged at either
side into the large gill-covers which protect the lateral gills.
Besides the distinct groove, other dorsal markings divide
the carapace more or less distinctly into regions. Of these,
the most distinct are the gastric region immediately behind
the rostrum, with a hepatic region at either side. Behind it
is the cardiac region, which has at either side the large
branchial regions. The regions are named after the organs
which lie beneath them, and are indicated in the figure of
the crab. The tail differs considerably from the anterior
part of the body, for it consists of six similar rings, each
carrying a pair of appendages, and an end piece, or telson,
without appendages. Each ring consists of an arched
dorsal portion, two projecting side flaps, a socket for the
limb, and a ventral bar with a spine in the middle.
Typically in the Crustacea the whole body should consist
of such rings, but in the three specimens chosen the
anterior thirteen rings are fused together, and are over-
lapped by the great shield, which has grown backwards
from the anterior segments. The function of this shield,
as already seen, is to protect the viscera and gills.
Perhaps at this point it may be well to interpolate a note
on terminology. To the beginner it may seem that the
greatest drawback to the study of Natural History is the
number of technical terms used to describe even the simplest
animal, and that the number of these terms has been need-
lessly multiplied. This last is perhaps a point which might
be debated, but we may notice that the use of technical
terms is justified on two grounds. First, they have perfectly
definite meanings, which cannot be said of the majority of
their Anglo-Saxon equivalents; and, second, they express
concisely, and in a word, a meaning which it would require
an English phrase to make clear. The term Decapod
Crustacea, for example, gives a naturalist a perfectly clear
idea of a group of animals which would in English be
inadequately described as "hard-coated animals with ten
legs." Although, therefore, an effort has been made to
156 LIFE BY THE SEASHORE.
keep down the number of technical terms in this book so
far as possible, they have been used whenever clearness and
conciseness would be sacrificed by their absence. Among
the Crustacea especially, a certain number of such terms
seem absolutely necessary, if the relation between the
different forms is to be made clear.
Returning to the study of the crayfish, it is obvious that
if the cephalothorax contains thirteen united segments, and
the tail six free ones, and each of these segments bears a
pair of appendages, then there must be nineteen pairs of
appendages, apart from the tail-piece, or telson. These
nineteen pairs of appendages are most easily studied by
beginning at the posterior end, removing the appendages of
one side successively, and laying them out in order.
In the following list they are for convenience described
from before backwards : —
(1) First antennae, or antennules, consisting each of a
stalk, or peduncle, and two short whips, or flagella.
(2) Second antennae, or antennae proper, consisting each
of a peduncle, bearing an outer broad flat scale, or squame,
and a long inner flagellum.
(3) The mandibles, hard, toothed plates, close to the
mouth.
(4) First pair of maxittce, or jaws, small, delicate, and
probably functionless.
(5) Second pair of maxillae, also very delicate, but
furnished with a plate — the baler — of much importance
in respiration.
(6, 7, 8) Three pairs of foot-jaws, or maxillipedes, con-
sisting of a basal piece and an inner and an outer branch.
The inner branch, especially in the third maxillipede, is
more or less leg-like (see b in Fig. 50).
(9) The great forceps, or chelipedes.
(10, 11, 12, 13) The four pairs of walking legs, all with
seven joints. (It is because of the presence of these five
pairs of "legs" (appendages 9-13) that the three types are
included in the order Decapoda.)
(14, 15, 16, 17, 18) The small swimmerets, typically
consisting of a basal piece and an outer and an inner
branch, but the first two pairs are more or less modified in
the male.
THE DECAPOD CRUSTACEA. 157
(19) The last pair of swimmerets, or uropods, large and
powerful, with the telson constituting the tail-fan.
Besides these nineteen pairs of appendages, we have the
large, compound, stalked eyes, which consist of a number of
eye-elements compacted together.
As the thoracic appendages are removed, it will be found
that some of the gills come away with them. Break away
the gill-cover at the other side of the specimen you are
dissecting, and you will see that the gills lie in a chamber
opening freely to the surrounding water in front and behind.
In order that the lobster may breathe, it is necessary that
these gills be continually washed with fresh water. When
the lobster is swimming, or in a typical swimming Crustacean
like the prawn, this is accomplished by the movement of
the whole animal through the water ; but in a state of rest
the lobster would asphyxiate were it not that its second
maxillae are in constant movement, and by baling the water
out in front cause a constant current to pass in at the
posterior end of the gill-cover. This is readily seen in a
living Crustacean by suspending fine particles in the water
in which it is living, and is a point of great importance.
It is an advantage to the Crustacean to have its delicate
breathing organs protected by a gill-cover, but this advantage
brings with it the necessity for a mechanical means for
constantly renewing the water beneath the cover. In crabs
the protection of the gills is more efficiently provided for
than even in prawn and lobster, and they are less actively
motile animals than either. The result is that the renewal
of the water under the gill-cover of the crab has to be
provided for by active means, and many of the striking
peculiarities of the crab are associated with this fact.
If you can obtain more than one specimen of Nephrops,
it is a good plan to dissect one, and then use the experience
gained to make a permanent preparation of another, laying
out the parts in order on a sheet of card or glass. The
flesh should be removed from the larger appendages, the
rings of the abdomen separated and cleaned, and the great
shield removed entire. During the process of preparation
you will find two skeletal parts which we have not yet
noticed — the so-called internal skeleton of the thorax, and
the gizzard. The former is a very complex structure, formed
158 LIFE BY THE SEASHORE.
in part by the fusion of the ventral and lateral elements of
the thoracic segments, and in part by additional structures.
It will be recollected that the cephalothorax or anterior
region is as truly formed of segments as the abdomen, but
that it is overlapped by the great shield which has developed
from the anterior segments. In consequence, the skeleton
of the overlapped segments has in part disappeared, in part
developed into the apparently internal skeleton which pro-
tects and covers the nerve cord.
The gizzard is that part called by cooks " the lady in the
lobster," and it contains firm limy bars bearing teeth which
clash against one another and grind the food. It should be
washed out and split open to see the teeth and bars.
When all the parts of the crayfish are cleaned and laid
out in this way, they can be left to dry, and the whole will
be found exceedingly useful for reference afterwards.
The next point is to compare the crayfish in detail with
the prawn. We have already noticed the similarity in
broad outline, but there are some interesting differences
in detail. Notice in the prawn the laterally compressed
beak, as compared with the flattened one of Nephrops;
this is of course associated with that difference in the shape
of the body which we have already noticed. The most
striking differences are, however, to be found in the nature
of the appendages. The filaments of the antennules are
long, and, if the prawn be a Palcemon, each antennule will
bear three instead of the two of Nephrops. This is a
point of minor importance, however, as compared with the
structure of the antenna. They will be found to have a
relatively enormous squame, or scale, as contrasted with the
small one of Nephrops; while the crab, again, has no trace of
antennal scale at all. The scale is a heritage from far-off
swimming ancestors, and diminishes in size as the swimming
power diminishes.
The maxillipedes of the prawn (Palcemon) resemble
generally those of the crayfish, but the walking legs differ
markedly, as already noticed. They are very long and
slender, the first pair especially being so slender as to
resemble feelers rather than legs ; they are habitually carried
folded upon themselves, and end in minute forceps. The
next pair are larger and stronger and also end in forceps,
THE DECAPOD CKUSTACEA. 159
and the last three pairs are simple, ending in sharp claws.
The legs will be found to differ a little in the different
kinds of prawns, but are always very different from those of
lobster or crayfish.
The tail is remarkable for the great development of the
five anterior pairs of swimmerets, as compared with those of
Nephrops. Most of the above points should be readily
made out from the accompanying figure.
If from the prawn we turn to the crab, we find well-
marked differences from both prawn and lobster. It is only
possible to point out some of these differences. The carapace
has been, as it were, strongly flattened out, and in the
process the rostrum has disappeared, and the relative posi-
tion of eyes, antennae, and antennules altered enormously.
Prawn and lobster swim rapidly, and as they swim their
long feelers, their freely movable eyes, make them fully
aware of their surroundings, while their vigorous tail strokes
remove them instantly from the dangers of which those
keen sense-organs give them notice. But the crab only
moves slowly ; it only requires to be made aware of its
immediate surroundings ; it is often content to offer a
passive resistance to foes. Therefore its antennae are
shorter, less prominent, and capable of more or less com-
plete retraction ; the eyes are sunk in orbits which protect
them from harm even if they also limit the field of vision.
The gills are more efficiently protected, and the parts about
the mouth are much modified. Again, while in prawn and
lobster more than one pair of legs bears terminal forceps, in
the crab it is only the first pair which is thus modified ; the
others are simply pointed, and used for locomotion only.
Let us look now at these points in a little more detail.
The carapace, or shield, of the crab is in essence similar to
that of prawn and lobster, and shows a similar division into
regions, but, besides being flattened and expanded laterally,
it is inturned at the anterior and lateral margins. This is
readily seen, and the change may be expressed in a rough
metaphor by saying that a crab's shield is like that of a
lobster which has been crushed flat. As a result in part of
this crushing, we find that the lateral area which in the
lobster or crayfish forms the vertical gill-cover has here
become horizontal, and is separated from the remainder of
160 LIFE BY THE SEASHORE.
the shield by a distinct movable suture The inturning of
the carapace in the frontal region has, as it were, carried in
with it the insertion of the antennules, so that we no longer
find these on the dorsal surface, but placed in little pits
beneath the margin of the shield. They are very short,
consist of one filament only, and are carried doubled up
when not in use. The eyes, instead of lying above the
antennules, are shifted outwards, and lie in somewhat elon-
gated sockets, or orbits, into which they can be completely
retracted. The very short antennae, without trace of scale,
are squeezed in between orbits and antennules. Their
peduncles are very short, the basal joints being lost in a
triangular plate which lies in front of the mouth.
FIG. 50.— Maxillipedes, or foot-jaws, of edible crab (A) and lobster (B). In
each figure, g is the gill, s the gill separator, ex the outer branch, en the
inner branch.
On the minor peculiarities of the mouth parts we need not
dwell. It is sufficient to note that they are more crowded
and overlap one another more completely than the similar
parts in the lobster. The point which is especially worth
notice, however, is the character of the third maxillipede-s.
As is seen in the figure, in the lobster these are distinctly
leg-like, but differ from the walking legs proper in that they
have a slender outer branch in addition to and arising from
the same base as the leg-like inner branch. The third
maxillipede of the crab has in essence the same structure,
THE DECAPOD CRUSTACEA. 161
but its inner branch, instead of being leg-like, is converted
into a flattened plate, covering over all the anterior ap-
pendages, and closing the anterior opening of the gill-
chamber. In Mysis, a simpler Crustacean than any of those
yet considered, all the eight thoracic appendages are similar,
all consist of a basal piece with a leg-like inner branch and
a slender outer branch. In prawn and lobster the anterior
three only retain this " biramose," or two-branched structure,
but they otherwise generally resemble the walking legs
proper, this being especially true of the third. In the crab
these three maxillipedes are fundamentally modified to sub-
serve functions connected with respiration and mastication,
and the structural gap between them and the true legs
attains its maximum. It is facts of this kind which induce
morphologists to regard the crab as more specialised than
the lobster, though it has lost some of the powers which
the latter possesses.
The legs of the crab will be found to display many in-
teresting peculiarities. The first pair are always the largest,
and constitute the main weapons of offence and defence.
Their shape and markings are often characteristic of the
species, and in many cases they fit in repose very closely to
the margin of the carapace, a point we shall consider later.
Near their base is the slit through which water enters the
gill-chamber ; a carapace which has been removed • with
sufficient care not to damage the movable gill-cover will
show a notch at this point. The remaining four pairs of
legs never bear forceps, and differ markedly in the shore
crab and the edible crab. They always form the organs of
locomotion, and are inserted laterally so as to form an
efficient support for the body. The last pair arises some-
what dorsally. An interesting point about them is that all
are made of six pieces only. In the lobster the chelipeds,
or great claws, have six joints, the other. legs seven. A
careful comparison will show that this is due to the fact
that in the great claws segments two and three, counting
from the base, are fused together, the line of junction being
clearly marked. When a lobster throws off its great claws,
as it often does when frightened or molested, separation
takes place at this junction line. A lobster only possesses
the power of throwing off its great claws, and not the other
M
162 LIFE BY THE SEASHORE.
legs ; but in a crab where all the legs display this peculiar
modification, any one of them may be thrown off. Separa-
tion always takes place at the one point, and the fusion
of segments is to be regarded as a special adaptation to^
facilitate this autotomy or self-mutilation. In this respect
also, therefore, the crab shows an increase of specialisation
as compared with the lobster.
Turning now to the ventral surface of our crab we find
that, as already noticed, the rudimentary abdomen is flexed,
and lies along the ventral surface of the thorax. But it is
much narrower than the thorax, and the lateral insertion of
the legs exposes the ventral surface of the latter much more
fully than in prawn or lobster ;. so we find in the first place
that this ventral surface is in the crab very firm and hard —
completely calcified. Bend the abdomen gently backwards,
and you will see that the thorax has a deep ventral groove
in which the abdomen habitually lies. The abdomen itself
bears rudiments of appendages, but these are much reduced.
Let us recall for a moment the abdominal appendages of
prawn and lobster or crayfish. In the prawn there are six
pairs of functional swimmerets, the last pair being much
the largest. In the lobster the first pair is rudimentary in
the female, and curiously modified in the male ; the next
four pairs are small and of little use in swimming, though
in the'female they carry the eggs ; the last pair is large, and
forms with the telson the powerful tail fan. In the crab,
with the reduction of the abdomen, we have the total
suppression of this tail fan, and the development of the
others varies in the two sexes. In the male the two
anterior pairs only are present, and are much modified ; in
the female four pairs are present; they are long and
delicate, and furnished with numerous hairs. As in the
lobster they are used for carrying the eggs. The number
of segments in the abdomen of crabs tends to be reduced,
more especially in the males.
We have thus briefly revised the main points of external
structure in three types of Decapods, and may look for a
little at the order in general. We have already noticed the
striking resemblances between prawn and lobster which
have led naturalists to classify them together as Macrura,
or long-tails, in contradistinction to the short-tailed crabs,
THE DECAPOD CRUSTACEA. 163
and have also mentioned that other possible division which
places the prawn as a typically swimming animal, in oppo-
sition to the creeping crab and lobster. Accepting this last
division, we find that the swimming Decapods, or Natantia,
have the following characteristics in common : The body is
always more or less compressed, as is also the rostrum. The
abdomen is well developed, its first segment is not markedly
smaller than the rest, but the second is usually very well
developed. The antennae have a five-jointed peduncle and
a large scale. The thoracic limbs are slender, are all seven-
jointed, and only in rare cases is the first better developed
than the others. Usually more than one pair are furnished
with chelae, and the penultimate segment is attached to the
antepenultimate by one fixed point or fulcrum only, so that
it swings less easily than in the Eeptant Decapods where
there are two fixed points. The abdominal appendages are
used for swimming. When the female carries the eggs
about with her, which does not invariably happen, the
second pair of swimmerets have a brood-lamella attached
to them ; this is seen in the common prawn (Palcemonji
Examples of Natant Decapods are shrimps and prawns, of
which there are many kinds. Our British forms are all
relatively small, but some tropical prawns attain a length of
nearly a foot. Most are more or less social, and are found
swimming in shoals.
With these swimming Crustacea are contrasted the
Reptantia, which have the following characters : The body
is depressed, with a flattened rostrum, or without a rostrum.
The abdomen is sometimes well developed and sometimes
reduced, but its first segment is always distinctly smaller
than the others. The peduncle of the antennae is reduced,
and the scale is sometimes absent. The thoracic limbs are
strongly developed, are usually six-jointed, and the first is
the largest. The penultimate joint is attached to the ante-
penultimate by two fulcra, or fixed points. The swimmerets
are always more or less reduced, and in the female always
carry the eggs.
It might be supposed that the Reptant Crustacea could be
sharply divided into two sets — the crabs and lobsters — but
we shall find that there are many transitional forms. Our
British forms are typically larger than shrimps and prawns,
164 . LIFE BY THE SEASHORE.
do not usually occur in shoals, and are often littoral. They
show much greater diversity of structure and habit than
the prawns, and have apparently been subjected to a much
keener process of selection. There are in consequence few
groups of marine animals which illustrate the problems of
evolution more clearly, or afford more fascinating objects
for study. One may read many books on the Doctrine of
Descent, and yet remain untouched by the charm of the
theory, but few persons can, I imagine, toil over the
structure and affinities of these Crustacea without suddenly
becoming conscious of the grandeur of the generalisation,
of its power of unifying what previously seemed insignificant
details.
We shall now proceed to consider successively typical
British representatives of the Decapoda.
The members of the sub-order Natantia all fall into the
family Caridida3 which has the characters of the sub-order.
A large number of genera are included in this family,
but it is only possible for us to consider a few of them.
We may repeat, however, that the great interest of these
forms is that on the one hand they show close relationship
to the next lower order of Crustacea, the Schizopoda, and
on the other they markedly resemble the Eeptant Decapods.
This is especially true of the lowest forms, notably the
curious shrimp Peneus, which seems to stand half-way
between the Schizopods and the crayfish and lobster. This
shrimp is, however, a Mediterranean form, and only occurs
very rarely in the South-west of Britain.
It is worth while to notice here that there are a number
of interesting Crustacea which are rare in Britain, and are
confined to the South and West. Such forms are almost
always Mediterranean species, and we may say generally
that our littoral fauna is of two types, the Mediterranean
type, which predominates on the South and West, and the
Northern, or Scandinavian type, which predominates on the
North and East. In addition, on the West we find certain
peculiar animals which are not truly members of our fauna,
but are brought, more or less passively, by the Gulf Stream.
Animals which occur all round our coasts may generally be
assumed to be common to the Scandinavian and Mediter-
ranean faunas, while our East Coast rarities are Scandinavian
THE DECAPOD CRUSTACEA. 165
types. The differences between East and West are often
exceedingly striking, and cannot fail, for example, to
astonish anyone passing from the Firth of Forth to the
Firth of Clyde. One must suppose that in many cases it
is the warm currents which wash our western shores which
have carried the Mediterranean animals northwards, but the
fact that the shore on the West Coast is generally more
rocky than the East, and is often fringed by deeper water,
has no doubt also much influence.
As Peneus is too rare to be described here, the first of
the Carididaa which we shall describe is the common prawn
(Palcemon serratus). This is the largest of our prawns, and
on certain parts of the coast, together with the much smaller
P. squilla, is the object of an important fishery. Both turn
bright red when boiled, and are so popularly distinguished
from the common shrimp, which merely turns a brownish
pink. A species of Palcemon may be instantly recognised
by the fact that each antennule bears three feelers, of which
two at least are very long, and by the fact that both the
first two pairs of feet are furnished with distinct forceps,
the second being much larger than the first. As other
characters we may note the large rostrum, which is strongly
toothed, and projects far forward between the eyes; the
position of the antennae, which are inserted beneath, and
only slightly to the outer side of the antennules ; and the
other characters incidentally noticed in the description of
the prawn.
As to the species, on the East Coast P. serratus is not
very likely to be seen except in a fishmonger's, but on
certain parts of the coast young forms are not infrequent
between tide-marks. The colour is greyish, with spots and
markings of brown and red. The rostrum is very long,
longer than the large scale of the antennae, and turns up at
the point, forming a cruel-looking weapon. It has eight or
nine teeth above, placed near the base, and five or six
beneath. The filaments of the antenna?, and two of those
of the antennules, are very long, so that the trailing threads
are very conspicuous objects. The strong abdomen, with
its well-developed appendages, has already been noticed.
The other common species of prawn (P. squilla, Fig. 47)
is also typically an inhabitant of deep water, but it occurs
166 LIFE BY THE SEASHORE.
not infrequently in rock pools, especially at low tides. Such
specimens are usually females carrying eggs. The colour is
greyish white with touches of brighter colour. The differ-
ences from the preceding species are not very well marked,
especially if only small specimens of P. serratus are avail-
able ; but it will be noticed that in the present form the
rostrum is nearly straight, and has seven or eight teeth
above, and only three beneath. The rostrum is also rela-
tively shorter, and it does not usually exceed the length of
the antennal scale. The whole prawn does not exceed two
inches in length. Either of these prawns will repay careful
study, for which their relatively large size peculiarly fits
them. There are some other British species of Palcemon,
but these are rare, and need not be considered here.
The next form to be considered is the Esop prawn, or
shrimp (Panddlus annulicornis), which, like the true prawns,
is typically an inhabitant of deep water, but is occasionally
met with in rock pools. It is of much the same size as
Palcemon squilla, which it resembles not a little, but is of
a somewhat brighter colour, the long antenna in particular
being in life beautifully ringed with scarlet. Like most of
the smaller Crustacea, it loses most of its beauty at death,
owing to the disappearance of the delicate transparency of
tint. In general shape and appearance the Esop prawn
resembles the true prawns, but can be distinguished from
them by the humped back, and by the different character of
the legs and antennules. In these respects it resembles the
next genus, Hippolyte, much more closely than Palcemon,
and the student should not fail to notice how closely the
three genera resemble one another, and how the Esop prawn
stands midway between the other two.
As to the detailed characters of Pandalus, notice that the
hump-backed appearance is due to the fact that the third
abdominal segment is pouch-like, being much longer on
the upper than the lower surface, so that the tail cannot be
completely straightened. Further, the antennules bear two
filaments only instead of three as in Palcemon, and one of
these is thickened and curiously curved. Again, the first
pair of legs end in exceedingly minute chela?, and the
second are slender, thread-like, and of unequal size. The
filiform appearance is in part produced by the fact that the
THE DECAPOD CRUSTACEA. 167
antepenultimate segment, which morphologists call the wrist,
or carpopodite, is broken up into a number of joints, so that
it resembles a whip in appearance.
The Esop prawn may be found not infrequently among
the " prawns " brought to market as food.
Much smaller than Pandalus or Palcemon are the various
species of Hippolyte, which are common on our shores, but
not being large enough for use as food are not well known,
and have no common name. The commonest form is
H. varians, a beautiful little creature, about three-quarters
of an inch in length, and showing much variation in colour.
It is typically green, but among dark weed brown varieties
are common, and in pools lined with Red Algse the tint
may be distinctly reddish. In common with the other
members of its genus it has the following characters : Like
Pandalus, it has a hump-back, which is due to the same
cause ; the antennules generally resemble those of Pandalus,
but the thicker filament is much curved, and furnished with
numerous bristles ; both filaments are short. It differs from
Pandalus in the nature of the first pair of legs, for these
are short, equal, and distinctly chelate ; the second and re-
maining pairs closely resemble the corresponding appendages
in Pandalus. There is usually a well-developed rostrum,
and it is the condition of this structure which is chiefly
relied on in the distinction of species. In //. varians it is
straight, furnished above with one spine near the base, and
one near the apex, beneath it is sharply keeled, and bears
two spines. The inner filament of the antennules is only
very slightly curved. These characters should be sufficient
to distinguish this species, which is the only one which can
justly be described as common in the littoral zone of the
East Coast. On the West, however, and especially the
South-west, another species is sometimes extraordinarily
abundant. This is H. cranchii, which in certain parts of
the Devonshire coast seems to occur in every rock pool.
In life it is of a delicate green colour, with the appendages
ringed with pale blue ; but the green colour is very fugitive
after death. It reaches about the same length as the pre-
ceding species, but the greater breadth of the thorax gives
it a much more robust appearance. The rostrum is short,
furnished with three teeth above, besides the two in which
168 LIFE BY THE SEASHORE.
it ends. Beneath there are no teeth. The two species show
very, little resemblance to one another. The other species
of Hippolyte being mostly rare or inhabitants of deep water
are beyond our scope.
Very little observation will convince the student that the
three genera just described resemble one another very
closely, and no difficulty will be found. in drawing up a list
of their common characters. All differ somewhat markedly
from the next genus we have to consider — that which
includes the common shrimp (Crangon vulgaris). Of this
abundant and familiar form it is always easy to obtain
specimens. In the tidal streams flowing between the rocks,
near the mouths of rivers, in sandy pools, wherever there is
abundant sand one may be almost sure of finding this
ubiquitous form, darting rapidly hither and thither, or
burying itself deep in the sand. In life, as everyone knows,
shrimps are sand-coloured, but examination with a lens will
show you that although the general tint be dull, the shrimp
is minutely speckled with brilliant red-brown spots of singu-
larly beautiful shape. When boiled, the true shrimp does
not become bright red, as do many of its allies, but merely
pinkish brown, and on this account is often called the
brown shrimp as a distinction from the prawns. The
common shrimp is the only species of its genus which can
be justly described as common on our shores, but as other
species do occur, especially on the West, we may take the
characters of the genus first, before mentioning those
peculiar to C. vulgaris. All the true shrimps differ from
the prawns in the following characters : — the carapace is
somewhat depressed instead of being flattened from side to
side, and the rostrum is rudimentary ; the abdomen is long
and very strong; the antennae are placed at the outer side of
the antennules, and not beneath them ; the antennal scale is
large, and the filaments of the antennules similar. The
legs are peculiar, especially the first pair, which are short
and stout, and exhibit the condition described as sub-
chelate. It will have been noticed that when hitherto
appendages have been described as ending in chelae, or
forceps, the chela3 have all been of the same structure.
That is to say, in each case the last joint ("movable
finger") has worked against an immovable prolongation of
THE DECAPOD CRUSTACEA. 169
tKe preceding joint, which formed the other half of the
forceps. In the shrimp the prolongation of the penultimate
joint is very minute, and the last joint is bent down sharply
upon the preceding joint ; this condition is described as sub-
chelate. The next pair of legs in the shrimp are very
slender and end in chelae ; the remaining legs end in simple
claws.
The common shrimp can be recognised by the following
special characters. The carapace has three spines only, a
median and two lateral; the abdomen is perfectly smooth,
and regularly marked with brown spots. It is the largest
British member of its genus, and reaches a length of two
and a half inches.
The great size of the antennal scales is a very obvious
feature of the shrimp, and it is interesting to note that in
burying itself it first makes an excavation by rapid move-
ments of the legs, and then completes the process by
shovelling sand over the body by means of the antennal
scales. It is a matter of common observation how complete
the burying process is.
This completes the description of the common types of
Natant Decapods. It should be clearly understood that
there are other British genera besides those described, but
specimens of them are rare in Britain, and have been
omitted. The descriptions given above will be sufficient to
make plain the general characters of these Crustacea as con-
trasted with the creeping forms next to be described.
170
LIFE BY THE SEASHORE.
KEY FOR IDENTIFICATION OF CRUSTACEA DESCRIBED
IN THIS CHAPTER.
DECAPODA (Crustacea with\ I. NATANTIA (swimming forms).
ten pairs of legs) . . f II. REPTANTIA (creeping forms).
I. NATANTIA. Family Carididne (shrimps and prawns).
Body depressed, rostrum"
rudimentary .
Body compressed,
well developed
\Crangon (common shrimp).
Antennules with
filaments .
Antennules with two fi\B.-\Pandaltis.
ments . . .) Hip^olyte.
Filaments of antenmiles^
long and sub-equal, \Pandaiu<*
first pair of legs very K '
long and slender . J
Filamentsofantennules
short, one thick and
curved, the other
slender and straight,
first pair of legs short
and distinctly che-
late
Hippolyte
f Rostrum curved, with eight
or nine teeth above, and
five or six beneath — P.
serratus.
Rostrum straight, with
seven or eight teeth
above, and three beneath
— P. squilla.
Rostrum very long, curved
upwards, anterior half
without spines, except for
a very small one near the
apex — P. annulicornis.
Rostrum with two spines
above and two below —
//. varians.
Rostrum with three spines
above, and a terminal
notch, none below — H.
cranchii.
NOTE ON DISTRIBUTION.
Little need be said on this point in addition to what is noted in the
text. Prawns, generally speaking, are commoner on the South and
West than on the North and East, and Palcemon serratus, at least, is
not likely to be found on the East Coast. But as the prawns are better
adapted for life in the open than between tide-marks, the occurrence
of large specimens in the latter situation is somewhat exceptional at
any part of the coast. The species of Hippolyte, which are small, are
common in rock pools, H. varians in most places round the coast,
//. cranchii on the South and West. I found it especially abundant
in the shore pools at Lynmouth, on the coast of Devonshire. Other
species of Hippolyte also occur. The common shrimp is found, where
the conditions are favourable, at all parts of the coast.
CHAPTEE IX.
THE DECAPOD CRUSTACEA : LOBSTERS, CRAYFISH,
AND THEIR ALLIES.
The common lobster and the Norway lobster — Their distribution and
characters — Structure and habits of the spiny lobster — Habits of
Galathea — Its structure and relation to the porcelain crabs — The
two common porcelain crabs — Their structure and habits — The
hermit-crabs — The northern stone crab and its relation to the true
crabs — The masked crab.
Reptant Crustacea form a much larger division than
_ the Natantia, for they include the greater number of
the long-tailed forms together with the crabs and their
allies. Their classification is a matter of some difficulty,
for, as already indicated, although crabs and lobsters seem
to be widely separated from one another, yet there are
transitional forms which connect them together, and make a
sharp division impossible. For our purpose it is, therefore,
sufficient if we consider the Reptantia as divided into a
number of families, without concerning ourselves with the
grouping of these families into larger divisions. Following
the same order as with the Natantia, we shall begin with
simpler or less specialised forms — those most nearly related
to prawns and shrimps.
The first family (As-tacidre) is that to which the cray-
fishes proper belong. The most important members of it
are the fresh-water crayfish (Astacus fluviatilis), a beautiful
little creature quite outside our sphere ; the true lobster
(Homarus vulgaris), and the Norway lobster (Neplirops
norveyicus). The last is never found between tide-marks,
but is at certain seasons brought to market in large numbers,
and is included here because it is readily obtainable, and is
171
172 LIFE BY THE SEASHORE.
so admirably suited for the study of the characters of Crus-
tacea." It is commonly called a crayfish, but this name is
applied indiscriminately by fishermen to all the larger long-
tailed Crustacea except the true lobster, just as shrimp is
applied to the smaller forms. The true lobster does occur
between tide-marks, but only at low spring tides, when it
may be found under overhanging rocks in the deeper pools,
threatening the too eager naturalist with the fate which so
nearly overtook the Mayor of Plymouth.
The characters of the family of Astacidae may be briefly
summarised as follows. The body is arched and slightly
compressed from side to side. The carapace has a distinct
cervical or neck furrow, absent in Carididae, and bears a
well-developed rostrum. The antennal scale is relatively
smaller than in the Carididae, and the antennae themselves
are placed beneath the antennules, not side by side with
them as in the higher Carididae. As in the latter, the third
maxillipede is elongated and leg-like. Each of the first three
legs ends in forceps, a condition paralleled in the Carididae
in the shrimp Peneus, but the first pair are much stronger
than the others, forming powerful weapons of offence and
defence. The tail is long and strong, and ends in a powerful
tail fan; the other abdominal appendages are more or less
rudimentary, but the first pair in the male are converted
into hardened styles. As already indicated, the Astacidae
stand much nearer Peneus and its allies than any of the
Natant genera which we have described in detail. We
must suppose that the higher Natantia (true shrimps and
prawns) and the Astacidae have both been derived, along
different lines, from ancestral forms which resembled
Peneus.
As we have seen, the three commonest forms included
under Astacidae are the fresh-water crayfish, the true lobster,
and the Norway lobster, and it is interesting to note that
although they can be distinguished with perfect ease by the
untrained eye, yet minute scrutiny does not bring to light a
great number of marked differences : there is much general
resemblance in structure. It is also interesting to note that
while there are a great number of fresh-water crayfishes,
widely distributed over the world, there are only relatively
few species of Homarus arid Nephrops.
THE DECAPOD CRUSTACEA. 173
The true lobster (Homarus vulgaris) is especially character-
ised by its relatively short rostrum, which only slightly
exceeds the peduncle of the antennae in length, and by the
fact that this rostrum bears three teeth on each side, and
none beneath. The very large chelipeds have the wrist
(carpopodite) furnished with four or five large conical teeth
on the upper border. Lobsters, as is well known, are usually
brownish blue in colour, marbled with white ; but there is
considerable variation in colour, full- red varieties not being
unknown. They do not inhabit very deep water, and are
usually caught off rocky coasts. According to the fishermen
they are very sedentary animals, rarely venturing far from
their particular haunts. This observation depends upon the
fact that they have a peculiar tendency to exhibit local
variations in colour, which is said to enable experts to name
the locality from which particular specimens have come.
Thick-shelled forms like the lobster cannot, of course, change
colour according to their surroundings, as delicate forms like
Hippolyte can ; so that if, as is generally supposed, the
colour of the lobster has a direct relation to that of its
environment, the adaptation must have taken place when
the lobster was very young, or must be the result of a
process of selection in each locality.
Lobsters are very widely distributed around the coasts of
Europe, and it is said that five or six millions are annually
taken in Northern Europe alone. Whatever be the exact
figures, there is no doubt that in most localities the in-
cessant persecution has greatly diminished their numbers,
and that in spite of the fact that the female lays 12,000
eggs at a time, and carries them about with her till they
hatch. Recently efforts have been made to protect what
is grotesquely called the "hen-lobster in berry" — that is to
say, the female with eggs, during at least a part of the year.
The Norway lobster, with its delicate colouring and thin,
elaborately sculptured shell, is a much more graceful animal
than the true lobster, and from its shape one would expect
it to be capable of much more rapid locomotion. It never
occurs near the shore, but lives in deep water, whence it is
obtained by trawlers. Though typically a Norwegian species,
it extends also in diminished numbers to the Mediterranean,
and is the object of an extensive fishery on the east coast
174 LIFE BY THE SEASHOEE.
of Scotland. It is curious to note that although at certain
seas >ns many hundreds are daily brought to market in
Edinburgh, almost all these are males, and an egg-bearing
female is very rarely seen ; one would therefore expect that
a rapid diminution of numbers is less likely to occur than
in the case of the lobster.
In the Norway lobster the rostrum is long, slightly
exceeding in length the peduncle or stalk of the antenna ;
it is furnished with three teeth at either side, and is hairy
beneath. The anterior part of the carapace (gastric region)
is furnished with seven longitudinal rows of spines. The
abdomen is beautifully marked, the markings being ac-
centuated by the distribution of the fine hairs. The great
claws differ much in shape from those of either lobster or
crayfish, for the propodite or hand is four-sided, the margins
being emphasised by the development of rows of spines.
The whole limb is elongated and slender, very different
from the broad and heavy chelipeds of Homarus. In colour
Nephrops is a delicate orange-red with brown hairs. It is
much smaller than the lobster, being usually seven to eight
inches in length. Young specimens may sometimes be ob-
tained from the trawlers, and make most charming pets.
They live well in confinement, but have most voracious
appetites, quite out of harmony with the fairy-like form and
delicate colouring. In such specimens the eyes are ex-
ceedingly conspicuous, and their peculiar "kidney" shape
should be noticed. It is this peculiarity which gives the
animal its scientific name (Nephrops = kidney-eyed).
It may, perhaps, be well to note here, for the sake of
future reference, the names given by systematists to the
typical segments of the legs of Crustacea. Beginning at the
outer end these are : dactylopodite, or finger ; propodite, or
hand ; carpopodite, or wrist ; meropodite, or arm ; and less
important, ischiopodite, basipodite, and basal coxopodite,
seven pieces in all.
The next family is that of the Palinuridce, including only
one British form, the splendid rock lobster or spiny lobster
(Palinurus vulgaris), a Mediterranean species found on the
South and West of England and off the coasts of Ireland.
Like many of its allies it is sometimes called a crayfish, and
is esteemed as an article of food in those districts in which
THE DECAPOD CKUSTACEA. 175
it occurs. It is a handsome creature, of reddish brown
colour mottled with white, with a strong superficial resem-
blance to the true lobster, from which it differs in certain
very marked respects. As indicated by its common name, it
frequents rocky coasts, the neighbourhood of Lundy being
an especially favoured spot. It does not occur on the East
Coast.
The point which will first strike the observer in Palinurus
is the total absence of the great forceps so characteristic of
lobster and crayfish. All the legs tire similar, and terminate
in simply pointed claws, though the first pair show in rudi-
ment the condition described as sub-chelate for the shrimp
(p. 169). Again, the antennules are half as long as the
body, but the length is given by the great elongation of
the peduncles, the flagella being exceedingly short. The
antennae are very long, longer than the body, and are borne
on very stout and spinose peduncles ; the scale is entirely
absent. The carapace is very densely coated with spines,
of which two are very large and project forward over the
eyes, but the rostrum is very small. In both sexes the first
pair of abdominal appendages is absent, the others are
simple in the male and two-branched in the female. These
are only a few of the peculiar characters of Palinurus,
which separate it so markedly from the Astacidae; the
absence of the great chelae is a point of special interest.
It lives chiefly upon the little Molluscs which cluster about
the rocks, and is one of the few Crustacea capable of
making distinct sounds, produced by rubbing movements
of a specially spiny part of the stalks of the antennae.
The Reptant Crustacea with which we have been hitherto
concerned have been large forms showing many points of
interest, but which at most can only be hoped for very
occasionally on the tidal rocks, and are therefore somewhat
beyond our proper sphere. On the other hand, the forms
to which we have now to turn are abundant everywhere on
the rocks, can sometimes be kept for a considerable period
in confinement, and are therefore objects of greater interest
to us. These forms are the species of Galathea, and the
porcelain crabs (Porcellana). We shall consider these two
genera together as forming one family, for though sometimes
widely separated, they show in many points great structural
176 LIFE BY THE SEASHORE.
resemblance. They are often separated, because the por-
celain crabs are in popular view crabs, while the Galathea
would popularly be described as a kind of lobster. We
shall see how nearly the two resemble one another, so that
this family, like not a few others, may be described as
linking crabs to lobsters.
First as to Galathea — when stooping over a rock pool
paved with promising stones, you will not unlikely see
darting through the water an animal whose movements are
so swift that it seems to be gone before you are well aware
of its presence. Momentary as the impression is, however,
it will probably have convinced you that the motion is
unlike that of a fish. If you employ all the artifices at
your disposal, and by draining the pool, removing its stones,
and searching its furthest recesses, compel the object of
your search to reveal himself, you will probably find a
Galathea. Even so, however, seeing is not catching, and
there is many a slip between the Galathea and the collecting
bottle. I well remember the first specimen I had the
fortune to catch. The chase had been long, and the pool
was deep, but at last the wary Crustacean had been got
into a corner, and heedless of her footing the would-be
captor made a sudden dart. It was successful, and for one
joyful instant I held the prize in my grasp. But it was
just an instant; there was a sudden jerk and a splash, and
I was left in the pool with one great claw in my hand,
while the Galathea twiddled his whiskers in insolent con-
tempt from an inaccessible crevice. I then learnt that the
"power of autotomy is possessed by the higher Crustacea
to a very marked degree," but that information, though
valuable, did not bring back the Galathea. Nor was I
much consoled on learning further that "the autotomy is
reflex and due to the stimulation of the sensory nerve,"
or in plain English that if I hadn't pinched the claw the
Galathea wouldn't have thrown it off, for I defy anyone
to catch a Galathea by one leg while floundering in the
water, and not pinch that leg. It is therefore better, on
the whole, not to catch your specimens by the legs, but
to try and gently persuade them to enter a net or collecting
bottle.
When caught, you will find that Galathea at first sight
THE DECAPOD CRUSTACEA.
177
somewhat resembles a very short and broad spiny lobster.
The colour is variable, but in the commonest species,
G. squamifera, which attains a length of about three inches,
the prevailing tint is usually brownish blue. Very young
specimens are, however, not infrequently brilliantly marked
with bright blue and red.
In marked contrast to
Palinurus, we find that
Galathea is furnished with
a pair of long chelipeds,
forming the first pair of
legs. In so far it resembles
the true lobster and cray-
fish, but it will be noticed
that only the first pair of
legs bear forceps, not
several pairs, as in cray-
fish and lobster. With
the gradual increase in
the creeping habit, and
the diminution of the
power of swimming, the
next two pairs of legs
take on as their primary
function that of support-
ino- thp hnrlv inrl ln«?p FlG- 51«— Scaly squat-lobster (GaZaMea squami-
oay, ana lose /gra) The ^^ is figurevd in a som^ewhat
their power 01 prehension, unnatural position, in order to show the
TVin ehirlpnf «V»rmlH nl«r> structure of the tail, and afford a basis of
me Student snouia alSO comparison with the lobster, Fig. 48.
not fail to notice that
with the broadening of the body, first obvious in Galathea,
the insertion of legs also moves outwards, so that the body
becomes more definitely adapted to the creeping habit. It
may, however, be objected that it is not obvious in what
respects Galathea shows a diminished power of swimming,
in view of the frequent difficulty in effecting its capture.
That it is not so good a swimmer as the true lobster can yet
be proved both from structure and habit. As to habit,
Galathea habitually creeps on its walking legs, and only
darts backwards on the sudden advent of danger. In
repose it keeps the tail bent — a trifling point, but one
fruitful in consequences. Then as to structure, compared
N
178 LIFE BY THE SEASHOEE.
with the lobster the tail is much shortened, relatively to
the cephalothorax, its muscles are greatly reduced, and in
short it is mechanically unfitted to function as an organ of
locomotion for more than a limited period.
Among the other interesting points of structure shown
by Galathea are the following. The antenna are not
beneath the antennules, but at the outer side of them.
The peduncle of the antennules is long, and the flagella
extremely short. This it will be remembered occurs also in
Palinurus, and it is also found in all the forms above
Galathea. The antennal scale is absent, as in Palinurus.
As in Palinurus, further, the first abdominal segment bears
no appendages in the female, and very rudimentary ones in
the male, in Galathea this segment is indeed considerably
reduced, owing to the sharp flexion of the body at the
junction of thorax and abdomen. This flexion and
reduction is, of course, universal among the crabs, and is
of some interest because some naturalists would regard the
reduction as directly the result of the pressure exerted
during the bending process. But it is important to notice
that the first abdominal appendages have disappeared in
Palinurus before the bending of the abdomen has begun.
Most of the above are characters indicating the approach
of Galathea to the crabs, in which these structural peculiar-
ities are further emphasised; but in addition Galathea shows
certain special peculiarities. Note especially the condition
of the last pair of legs. These are reduced to mere rods
with a terminal brush of hairs and rudimentary chelae, and
are habitually carried tucked underneath the gill-cover.
In the figure they are shown spread out. The gill-cover, it
will be noted, is no longer vertical, as in the crayfish, but is
now oblique in position, and separated from the shield by a
suture. The well-developed rostrum with spines character-
istic of the species should also be noticed, and the reduction
of the abdominal appendages, whose only function seems
now to be to carry the eggs in the female.
Two species of Galathea are common on our shores. The
commoner is G. squamifera, while the larger, G. strigosa, is
more usually found in deeper water.
The first-named species has a short rostrum ending in a
spine, and bearing four spines on each side, the last being
THE DECAPOD CRUSTACEA. 179
the smallest. The chelae bear spines, but only on the inner
margin of the meropodite and carpopodite (arm and wrist),
and the outer margin of the propodite (hand).
In the spinous Gdlathea (G-. strigosa) the rostrum has
only three teeth on each side, and the great claws bear
numerous spines on both margins. The two species are
very neatly distinguished by the structure of the maxilli-
pedes, as will be seen on reference to the table at the end of
the chapter.
The next forms to be considered after Galathea are the
little porcelain -crabs, very different in appearance from
G-alathea, less active and less beautiful, but no less interest-
ing. As already indicated, the porcelain-crabs are sometimes
widely separated from Galathea,
but we shall consider both here as
belonging to the same family
(Porcellanidse), for they seem to
be closely related.
We have two British species of
Porcellana, both very abundant,
and occurring on the shore rocks.
The larger, P. platycheles, is to be
SOUght under Stones in muddy FIG 52. — Hairy porcelain-crab
nnnlcj TliP rra'h r!r,P« nnf UVP in (Porcellana platycheles). The tail
pools. me crab does not live in isinthe naturai position, that
mud, SO that the Stones must be is< completely bent beneath
those which from their position
have a cavity beneath them, and the likeliest pools are
those traversed by a little stream of water. Turn over
such stones, and you will see on the upturned surface small
muddy crabs with large flattened chelipeds, whose one
method of defence seems to be the passive one of crouching
down, with the curious great claws, which are densely
fringed with hair, arranged at such an angle that they re-
semble nothing so much as a flattened pebble adhering to
the stone by means of a layer of mud. It is curious that
although very common, and found considerably above low-
tide mark, these crabs are familiar to very few people.
This is partly because the localities which they haunt are
not those in which the collector usually lingers, partly no
doubt because the habit of crouching down and the coating
of inud make them very inconspicuous.
180 LIFE BY THE SEASHORE.
The other species, P. longicornis, though smaller, is much
more conspicuous and brighter in tint. It is found under
stones also, but not where there is mud, and usually in-
habits deeper water than its hairy congener. My best
specimens have been obtained from the roots of Laminaria,
either pulled out of the deeper pools, or cast on shore after
storms. The last constitutes a very important source of
supply for the smaller and rarer Crustacea. After many
an easterly gale the shore is strewn with giants from the
marine forests, and every plant has brought away with it
countless forms of animal life which once lodged in its
roots, stems, and fronds.
Presuming, then, that you have obtained specimens of
both crabs, and that by a dexterous use of a camel's-hair
pencil you have removed a portion of the mud from the
hairs of P. platycheles, and so succeeded in revealing its
shape to some extent, we will consider the characters of
the genus.
Both differ very markedly from Galathea in the shape
of the carapace, for it is almost circular and much depressed
— in other words, truly crab-like. The abdomen is com-
pletely flexed, as in crabs in general, but it is large, retains
its seven distinct parts, and ends in a distinct, though
small and delicate, tail fin. You should not fail to notice
that, as in Galathea, the telson, or tail-piece, is curiously
marked, being composed of several pieces. As to the
appendages, the small antennules and the very long antennae
in essentials resemble those of Galathea. The third maxilli-
pedes are very interesting, because they present some general
resemblance to those of Galathea and the lobster; but yet
in the expansion of their basal joints they show an approach
to the shutter-like structure seen in the true crabs. As a
special peculiarity they exhibit a dense fringe of long hair
on the inner margin of their terminal joints. The structure
of the great claws differs in the two species, but in both
cases they are so modified by the hollowing out of the wrist
(carpopodite), that they can be held in a retracted position
(see Fig. 52). This is characteristic of the crabs as com-
pared with the long-tailed forms, which carry their chelipeds
outstretched. The next three pairs of appendages are walk-
ing legs, used for the support of the body. As in Galathea,
THE DECAPOD CRUSTACEA. 181
the last pair of legs is modified to form two slender rod-like
structures, habitually kept folded beneath the lateral margin
of the carapace, and terminating in minute chelae with a
brush of hairs. In the figure they are represented in the
unfolded condition. Besides the terminal swimmerets, the
abdomen in the female bears four pairs of slender hairy
appendages used for carrying the eggs, -while in the male
there is only a single pair of slender rods. The reduction
of the abdominal appendages in the male should be noticed,
as it is very characteristic of crabs compared with long-
tailed forms. The appendages of the male belong to the
second abdominal segment, and the appendages of the first
segment are also absent in the female, as in crabs. The
porcelain-crabs are passive little creatures as a general rule,
showing marked preference for secluded situations, and
clinging tightly- to stones or weed when disturbed. In
spite, however, of the crab-like appearance, they still retain
the power of swimming, as may be often seen in captivity
in the minute porcelain-crab. Occasionally this species
gives up its sedentary habits and takes to active swimming
through the water. The motion is, of course, backwards,
and it is very curious to notice that although it begins its
journey in the normal position, the weight of the heavy
claws seems to invert the body, and it very speedily falls
over on its back. It is a very interesting sight to see the
little creatures lying on their backs in the water and
propelling themselves backwards by vigorous jerks. It is
obvious that under such circumstances the long antennae
are of much use in helping to direct the movements and
avoid collisions. I have never seen the hairy porcelair-
crab swim, and if it does so the heavier claws must hand'-
cap it considerably, and make tbe movement exceedingly
fatiguing. The whole shape of the claws is considerably
more crab-like than in the other species, and from the
nature of its habitat one would not expect that swimming
would be frequently indulged in. Both it and the smaller
species, when turned on their backs, flap their tails to assist
their efforts to regain the natural position. In specimens
kept in confinement the dense fringe of hairs on the third
maxillipedes should also be noticed. In the hairy porcelain-
crab the hairs are used as a comb to clean the antennae and
182 LIFE BY THE SEASHORE.
antennules from any adhering particles of mud — a very
necessary matter in animals living ' in muddy situations.
Both species have also a habit of holding the fringes out
at arm's length, and then sweeping them inwards ; it is
probable that in doing this food -particles are entangled
among the hairs, which thus serve as fishing-nets.
There is no difficulty in distinguishing between the two
species of porcelain - crabs, for they are very unlike one
another in appearance.
In P. platycheles the carapace is usually about half an
inch broad, and the length of the great claws is somewhat
over an inch. The upper surface in life is so densely
covered with fine mud that no colour is visible ; but the
under surface is whitish, and when carefully cleaned the
upper has a reddish tint. The hairy porcelain-crab, as it is
called, is a very interesting species on account of its adapta-
tions to a life in turbid water. It has been proved by
experiment that, hardy as the common shore crab is, water
containing mud is extraordinarily fatal to it. This is due to
the fact that the gills, as in all Crustacea, are external
structures, though they lie within a protecting gill-chamber.
In consequence they are exposed to the action of the mud
in the water of respiration. The particles settle on their
surface, and produce an effect which is, in a rough way,
analogous to the effect produced by deposits of dust in our
lungs, and this speedily asphyxiates the crab. If, therefore,
a crab is to live in sand or mud, it must have a special
mechanism to prevent the particles gaining access to the
gills. This is generally effected by the development of
hairs, placed on the general surface of the body, but
especially on the path of the respiratory current. The chief
point of entrance of the water to the gill-chamber is in most
crabs at the base of the great claws. If' you examine For-
cellana platycheles when at rest on a stone, you will see that
the legs in general, but the great claws in particular, are
densely fringed with hairs. These hairs, as is easily seen,
act as sieves, entangling the fine particles, and allowing pure
water only to pass through them. The sifting action of the
hairs is greatly increased by the fact that they are branched
and serrated, a point easily demonstrated by microscopic
examination. The third segment of the rudimentary legs is
THE DECAPOD CRUSTACEA. 183
also hairy, and in life lies at the sides of the carapace, pre-
venting the access of mud to the posterior part of the gill-
chamber. These legs are also periodically unfolded, and
their terminal brush of hairs used to clean out the groove
and remove any adhering particles. This curious manoeuvre
may often be seen in forms kept in confinement. We have
already noticed the similar cleansing process practised on the
sensitive feelers.
The special characteristics of P. platycheles are its general
hairiness, and the large size and flattened shape of the cheli-
peds. The front of the carapace is furnished with three
triangular teeth, the middle one being the largest.
The minute porcelain - crab (P. longicornis) usually
measures in large specimens under a quarter of an inch
across the carapace. In the males the colour is bright red,
but is somewhat less brilliant in the females. The great
claws are of unequal size, and are more or less prismatic in
shape. Like the rest of the body, they are quite smooth
and devoid of hairs — a marked contrast to the preceding
species. In the male, however, the " fingers " (chelae) of the
left great clawr are curiously twisted, and covered internally
with a dense pubescence of brown colour. The "fingers" of
the female are less markedly twisted, and the pubescence is
absent. In both sexes the antennae are about twice as long
as the carapace, and the front of the carapace is furnished
with three teeth, of which the middle one is deeply
grooved.
Both the porcelain-crabs are abundant at most parts of the
shore, and live well in confinement.
The next family is the PaguridaB, including our own very
curious hermit-crabs and the cocoanut-crabs of the tropics.
All these have long abdomens, like true Macrura, but the
abdomen is more or less soft, unsegmented, and usually un-
symmetrical. Most of the forms have in consequence
acquired the curious habit of availing themselves of the
shells of other animals, usually Gasteropods, and carrying
these about with them as a house. The appendages of the
abdomen are correspondingly reduced, the chelipeds are very
large and usually of unequal size, and the two last pairs of
walking legs are reduced.
The true hermit- or soldier-crabs belong to the very large
184 LIFE BY THE SEASHORE.
genus Pagurus, often divided into a number of sub-genera ;
it will be sufficient for us to consider the British species as
belonging to Pagurus itself, although they strictly fall into
the sub-genus Eupagurus.
On the East Coast there is only one common species near
the shore, and that is P. bernhardus, or Bernard the Hermit,
as it is commonly called abroad. Of this form small
specimens are abundant, often extraordinarily abundant, in
all shore pools. In the Firth of Forth after storms the
beach is sometimes literally paved with hermits, and every
FIG. 53.— Common hermit-crab (Pagurus bernhardus) in the shell of the whelk,
rock pool has its representatives. These inshore forms
inhabit the shells of the different species of periwinkle,
Trochm, Purpura, and of the smaller whelks, often much
damaged specimens — the broken top of a very large
"buckie" seems indeed to arouse specially keen competi-
tion. The size of the hermits depends upon that of their
habitation, for the hermit changes its shell as it grows, so
that all these specimens are necessarily small ; the fact that
many of them will be found to be carrying eggs shows,
however, that maturity does not depend on size alone.
When removed from their shells it will be seen that all
these forms have an abdomen of blue colour. With these
THE DECAPOD CRUSTACEA. 185
the hermit-crabs dredged from deep water, or cast ashore
after storms, seem at first sight to be markedly contrasted.
They inhabit the large shells of full-grown specimens of
Fusus or Bticcinum, shells often nearly six inches in length
and heavy in proportion, and the hermits reach a size
commensurate with that of their dwellings. The abdomen
is a deep brick-red, and the rest of the body deeper in
tint than in the shallow-water forms. It requires some
study to convince one's self that such hermits are not specifi-
cally distinct from the more familiar forms found on the
tidal rocks, and the fact that the latter become mature in
shallow water, almost justifies one in speaking of them
as a variety.
One other point of interest about the hermits is their
habit of living in symbiosis or partnership with other
animals. In certain localities the hermits very commonly
inhabit shells covered externally by the beautiful zoophyte
Hydractinia. This seems, however, to depend very largely
upon the locality. Most hermits from deep water have, as
companions within their shells, one or more specimens of a
very beautiful worm, Nereis fucata (see p. 106). So common
is this association, that in some places fishermen catch the
hermits, and turn them out of their shells for the sake of
the partner worms, which are used as bait. It is not easy
to see what the hermit gains by the presence of the worm,
but at least it is not injured by it, as it is by another
common associate, the parasitic Peltogaster, which hangs
like a sac from the under surface of the abdomen in very
many hermit-crabs.
As everyone who has tried to keep hermits in confinement
knows, they are exceedingly sensitive to unfavourable con-
ditions, especially to a diminished oxidation of the water.
The first sign of discomfort displayed is the tendency to
quit the shell, or to change rapidly from one shell to another,
and this restlessness is usually quickly followed by death.
It is difficult to say whether this delicacy of constitution
is due to a difficulty in respiration produced by the shell,
or to that racial decadence which has made the appropriation
of the shell necessary. If, however, you wish to keep the
hermits alive, they must be allowed a large bulk of water,
as frequently renewed as possible. Under such conditions
186 LIFE BY THE SEASHOEE.
they form very interesting pets; the explorations in all
directions carried on by the long antennas, the flickering
movements of the antennules, the sudden recoil within the
shell at the approach of danger, and the peculiar gait, should
all be noticed. Also the fact that just as the original owner
of the shell was an unsymmetrical, twisted animal, so also
the body of its present possessor is distinctly lopsided and
coiled. The want of symmetry is indicated externally in
the inequality of the great claws, but is more obvious when
the dying hermit drags its soft body out of the stolen shell,
and shows all its twisted length.
In the dead specimens the following points can be made
out. Though the great claws and walking legs are strongly
calcified, the rest of the body is soft and thin-skinned. The
carapace is delicate, and does not cover the last thoracic ring,
which is free, as it is in the last family. The abdomen is
much longer than the cephalothorax, and is twisted to the
right side. The antennae are very long, are placed beneath
the antennules, and have a rudimentary scale. In their
general structure the antennules resemble those of the last
family, that is to say, their filaments are short as contrasted
with the long ones of lobster and crayfish, and the upper
is thickened and fringed with hair. The eyes have very
long stalks and are very mobile. We have already spoken
of the inequality of the great claws ; the next two pairs of
legs are simple, very long, and strongly calcified ; they are
used for locomotion. The last two pairs, on the other hand,
are shortened and greatly reduced. They do not project
from the shell, and as in the case of the last pair of legs
in the preceding family, terminate in very rudimentary
chelaa. The abdomen has mere traces of calcification on its
upper surface, but terminates in a distinctly calcified telson,
which shows some signs of being, as in the preceding family,
calcified in several pieces. In both sexes the last pair of
abdominal appendages is present; the left is much better
developed than the right, and forms a sickle-shaped structure
which attaches the hermit to its stolen shell. The right
appendage is smaller, but is also hard and of somewhat
similar shape. Besides these paired appendages the left
side of the abdomen in the female bears four unpaired
appendages, of which three are anterior, very hairy, and
THE DECAPOD CRUSTACEA. 187
used for carrying the eggs. The fourth, separated by a long
interval, is very much smaller. In the male there are three
unpaired appendages of small size. The unsymmetrical
condition of the abdominal appendages in Pagurus is a
point of much importance.
We shall only mention here two species of Pagurus, the
common hermit, P. bernhardus, and the closely related P.
prideauxii of the West. "Bernard the Hermit" is recog-
nised by the fact that the great claws have their surface
covered with spinous tubercles and granules, and that the
terminal segment of the walking legs is twisted and
expanded. It is abundant everywhere.
The P. prideauxii of the West Coast is very similar to
the common hermit, but the chelae are less tuberculated,
and the last joint of the walking legs is scarcely twisted,
not flattened, and grooved at each side. This form does not
occur on the East Coast, but is included here on account of
the interesting fact that it almost always bears the sea-
anemone Adamsia palliata on the back of its shell — another
interesting case of commensalism in these hermits. In the
Clyde, and on other parts of the West and South, P.
prideauxii and its messmate are abundant.
The other numerous British species of Pagurus mostly
live in deep water, or are confined to the South and West.
The hermit-crabs possess so many obvious peculiarities
that they are quite unmistakable, but the next crab we shall
consider, though probably nearly related to the hermits, is
not infrequently erroneously described as a spider-crab.
This is Lithodes mala, the northern stone-crab, an animal
interesting alike in its distribution, its structure, and its
superficial resemblance to the true spider-crab Mala. As
the common name indicates, it is a northern species, one of
the few forms whose presence on the East Coast compensates
for the absence of the rich Mediterranean fauna of the
West and South. It attains a large size — a span of twenty
inches, with a breadth of carapace of four inches, and
inhabits deep water. Though not a littoral form, it is,
however, included here because of its interest, and because
it may be not infrequently obtained from friendly fishermen,
and occasionally finds its way as a curiosity into fishmongers'
shops. Anyone accustomed to the Crustacea of the West
188 LIFE BY THE SEASHORE.
seeing a specimen for the first time, and noting the length
of leg, the triangular carapace, and the dense coating of
spines, is likely at once to pronounce it to be a spiny spider-
crab. Not infrequently he writes to the newspapers to
proclaim the fact; the spiny spider-crab as an inhabitant
of the North-east may indeed be relied upon to appear as
regularly as the nightingale, the humming-bird, the sea-
serpent, and the other phenomena of the dead season.
If you are fortunate enough to obtain a specimen, you
may easily enough demonstrate to yourself the reasons why
Lithodes is not a spider-crab, but is relegated to a family of
its own, the Lithodidae, which is placed at a considerable
distance from the true crabs.
The stone-crab has a triangular spiny carapace prolonged
into a long rostrum, which bears eight spines. There are
no orbits, or eye-sockets, and the eyes are placed at the
inner side of the antennae (contrast crabs). The antennules
lie beneath the eyes, and have a very long stalk, and very
short flagella (cf. hermit-crabs). The antenna? are long, and
placed not in a complete socket, but in a gap between a
spine on the carapace and one on the anterior end of the
gill-cover (cf. Porcellana, and contrast crabs). The gill-
cover itself is nearly vertical (cf. Pagurus and Galathea),
and divided into several pieces. As in Pagurus, the last
ring of the thorax is movable, and is not covered by the
carapace, and its appendages are greatly reduced, and
concealed in life beneath the carapace. As in Pagurus and
Galathea, the third maxillipede is completely leg-like, and
does not form an operculum, as in the true crabs. The first
pair of legs only are truly chelate, the others are very long.
Both carapace and legs are spiny, and are of the same dull
red colour.
So far Lithodes has only been seen to resemble Pagurus
in those points in which Pagurus itself resembles Galathea,
or even more distant forms, but in the structure of the
abdomen, Lithodes, on the other hand, shows a striking
affinity to Pagurus, and to Pagurus alone. In Lithodes, as
in Pagurus, the abdomen is incompletely calcified, the first
two segments are large and visible on the dorsal surface, the
remaining segments are permanently flexed beneath the
thorax. In the female these segments are markedly un-
THE DECAPOD CRUSTACEA.
189
symmetrical, the left side being better developed than the
right, and bearing four unpaired appendages used for
carrying the eggs (cf. Pagurus). In the male the abdomen
is symmetrical, but uncalcified, except for small lateral plates.
The student should not fail to notice that the four genera
just discussed — Galathea, Porcellana, Pagurus, Lithodes —
show in several respects close interrelationship. The point
of special interest, however, is that they fall into two sets
— Galathea and Porcellana on the one side, and Pagurus
and Lithodes on the other — and that in each set we have
a long-tailed (macrurous) form (Galathea in the one and
Pagurus in the other) and a short-tailed form (Porcellana
arid Lithodes), the brachyurous characters having been
acquired independently
in the two cases. The
fact will serve to illus-
trate what is meant by
saying that the Deca-
pods cannot be logically
classified into Brachyura
and Macrura, for not
only are forms like
Galathea and Porcellana
transitional between the
two, but the brachyurous
habit seems to have been
acquired independently
in several groups, and
the rigorous application
of the classification must
result in the separation
of closely allied forms.
Thus if we put porce-
lain-crabs and the stone-
crab together among
other crabs, as is often done, we necessarily ignore the fact
that they are more closely allied to Galathea and the
hermit-crab respectively than to one another.
The next form to be considered is the pretty little
masked crab (see Fig. 54), Corystes cassivelaunus, be-
longing to the family Corystidse, which includes only one
FIG. 54. — Masked crab (Corystes cassivelaunus).
In part after Herbst.
190 LIFE BY THE SEASHORE.
other British genus. The masked crab is not very often
found between tide-marks, as it usually lives in sand in
fairly deep water, but it is a species very commonly cast
upon the shore after storms, and may often be found even
in summer among the dried masses of wreckage at high-
tide mark. The not very appropriate English name was
given to it by Bell because of the fact that the regions of
the carapace are very distinctly marked, and their grooves
are so arranged as to form a somewhat indistinct outline
of a man's face. This is only apparent in fresh specimens,
and at times is considerably more like a lion than a man.
Fresh specimens are pale red in colour, but the colour soon
fades to bluish white. In length the carapace usually
measures rather over an inch, and it is one-third longer than
broad. The sexes are easily distinguished, for while in the
male the chelipeds are twice as long as the body, in the
female they are of the same length. Further, as in the true
crabs, there is a fusion of abdominal segments in the male,
so that while the abdomen of the female has several pieces,
that of the male only appears to have five. As in all the
remaining Decapods, the abdomen is kept permanently
flexed beneath the carapace, is very small, and without
trace of tail fin; it is broader in the female than in the
male, and it bears four pairs of egg-carrying appendages,
as compared with the two pairs of small rods in the male.
The eyes are placed in orbits into which they can be
retracted. In all these respects Conjstes resembles the true
crabs; in the following it resembles the long-tailed or
anomalous forms which we have just been considering, or
is peculiar.
The antennae are long, and are supported on long, flexible
stalks, whose three joints are all freely movable and inserted
at such angles as to bring the two antennae very close to
one another. They are placed beneath the eyes, the orbits
of which would be widely open below were it not for the
basal joint of the antennal peduncle. The third maxilli-
pedes are long and narrow, but in the reduced size and
method of insertion of the three terminal joints they recall
those of true crabs. The first two segments of the abdomen
are visible on the dorsal surface, and the first is much better
developed than in crabs, in which it is more or less reduced.
THE DECAPOD CRUSTACEA. 191
The masked crab is very easily recognised owing to the
peculiarly elongated shape of the carapace, which terminates
anteriorly in a deeply notched rostrum, and is furnished
with three distinct spines. These points are readily made
out in the figure. The elongated antenme are also peculiar
and characteristic. As already indicated, the nature of
their insertion is such that the inner surfaces of their flagella
are, or can be, closely apposed. These apposed surfaces are
densely fringed with hair, and, according to Mr. Garstang,
the respiratory current is at least at times downward through
the tube formed by the antennae. It will be recollected
that in Crustacea in general the gills are washed by a
constant stream of water which enters the gill-chamber at or
near its posterior end, and leaves it anteriorly near the
mouth. We have already noticed in the mud-loving Por-
cellana platycheles that the numerous hairs covering the
body sift the mud from the incoming water, and so protect
the delicate gills from injury. The masked crab usually
lives buried in sand, with only its long feelers protruding.
It is obvious that in this position it is almost impossible
that the respiratory current should be of the usual postero-
anterior type, and we therefore find that it is at least at
times reversed, entering at the anterior end of the gill-
chamber after passing down the antennal tube, and leaving
at its posterior end. The dense hairy fringe of the antenna
sifts out the particles of sand just as the mud is sifted out
in Porcellana. The great flexibility of the antennal stalks
also permits of the periodic cleaning of the antennas by the
drawing of one over the hairy surface of the other.
It is interesting to note that another member of the
family Corystidee, Atelecyclus heterodon, also occurring on
British coasts, approaches both in appearance and in struc-
ture the crabs much more nearly than does Corystes itself
It is exclusively an inhabitant of deep water.
192
LIFE BY THE SEASHORE.
KEY FOR IDENTIFICATION OF ABOVE CRUSTACEA.
II. REPTANTIA, creeping forms including lobsters, hermit-crabs and
their allies, and true crabs (see next chapter). For full definition of
Reptantia, see p. 163.
Of the five pairs ^
1. Fa,, AstacM,.
2. Fara.
ridse.
Pal inn -
3. Fam. Porcel-
lanidae.
(chelae)
None of the legs \
bear forceps . J
One pair of legs , Tail fan present, -\
only with for- abdomen sym- V
ceps. Last pair I metrical .J
of legs or 1 No tail fan, ab- /-Tail long and . v -n • i
last two pairs domenunsym-{ soft . . 4. Fam. Paguridae.
aborted . * metrical . ^Tail intumed 5. Fam. Lithodidre.
, Fam. Corystidae
(distinguished
from true crabs by
long antennae and
leg-like maxilli-
pedes).
Common lobster, Homarus
vulgaris. For specific char-
acters see text.
Norway lobster, Nephrops nor-
kidney-shaped . / vegicus. See text.
One pair of legs^
only with for- I
ceps. All legs |
normal . J
1. Fam. Astacidae. T Rostrum short,
Long - tailed J eyes rounded .
forms with largel R ^ ,
antennal scale . I
2. Fam.
ridae
[
-
Spiny forms witrn
Palinu- long antennules !
.j and no antennal |
I scale . .J
3. Fam. Porcel-
lanidae. Last
pair of legs re-
duced to rods .
^Carapace ovate,
with distinct,
rostrum — Gala-
thea
Carapace nearly
circular, with-
out distinct ros-
trum — Porcel-
lana .
Rock lobster, Palinurus vul-
garis, the only British
species.
In G. squamifera the meropo-
dite (p. 174) is longer than
the ischiopodite, and bears
one large terminal spine and
five little ones.
In G. strigosa the ischiopodite
is longer than the meropo-
dite, which bears two
spines.
'In P. platycheles the body, and
especially the chelipeds, are
covered with hair.
In P. longicornis the body and
chelipeds are smooth.
THE DECAPOD CRUSTACEA.
193
4. Fam. Paguridne.^ n, ,. -, - fin Eupagurus bernhardus the
Abdomer! long Chelipeds of un- ohelipeda bear Spinous tu-
,„,] __r>i. _I-~T ii equal size, tne i i »*_
and soft, shel-
tered within
Mollusc shell .
-Eupagurus
bercles.
i E. prideauxii they are less
tuberculated.
^m;^odit;| Rostrum long, last^
turned but in- 1 pair of le°s ™^~ l°nly British species, LithocUs
completely cal-
cified
mentary — Li- j
thodes , . J
Fam.Corystid*. fCarapace ovate- C
Antenna/ longJ Corystcs ' *\
ritish
' Cory.stss_
masked
and hairy
. I Carapace circular /Only British species, A.
v — Atelecydus .\ heterodon.
NOTE ON DISTRIBUTION.
There is much that is interesting in regard to the distribution of
the Crustacea mentioned in this chapter. While the common lobster
occurs everywhere in suitable localities, the rock lobster (Palinurus)
only occurs on the South and West, and is most abundant in the
South. On the other hand, the Norway lobster, so abundant off the
East Coast of Scotland, is rare in the South and South-west of England.
On the East Coast, e.g. at St. Andrews, the scaly Galathea (#.
squamifera) is the only species of Galathea found between tide-marks ;
at places like Ilfracombe and Torquay G. strigosa and other species are
to be found there. The porcelain-crabs seem to occur wherever the
conditions are favourable. Of the hermit-crabs the common one
occurs everywhere, while E. prideauxii is confined to the South and
West, where, however, it does not occur between tide-marks. The
northern stone-crab (Lithodes) is confined to the Northern parts of
our area, and is especially abundant off Aberdeen, where it reaches a
great size. The masked crab and its ally Atelecydus occur at most
parts of the coast where the conditions are favourable.
CHAPTEE X.
THE DECAPOD CRUSTACEA— THE TRUE CRABS.
Common spider-crabs — Their coating of weed — The general characters
— The edible crab — Its distribution and habits — The shore crab —
Different kinds of swimming crabs — The pea-crab — Movements of
the Decapod Crustacea — Process of moulting — Development of
Crustacea.
IN this chapter we have to consider the true crabs, one of
the most interesting groups of the Crustacea, including
forms which are essentially littoral in habit. We have
already seen that the porcelain-crabs, the stone-crab, and
the masked crab, show striking external resemblances to the
true crabs, such as the spider-crabs, the shore crab, and the
edible crab, so that a little care is necessary in defining the
Brachyura, or short-tailed true crabs, in the narrow sense.
That the carapace is usually broad in proportion to its
length, and the tail small without tail fan, and reflexed
beneath the body in all crabs, it is hardly necessary to
repeat. More subtle points are the fact that eyes, an-
tennules, and antennae, are placed in complete sockets, that
the third pair of maxillipedes form flattened plates (opercula)
instead of being leg-like, and that the whip (flagellum) of
the antennae is always short. Lest it should seem, however,
that this distinction has been made too sharp, it should be
carefully noted that in the curious rounded crab Atelecydus,
mentioned in the last chapter, the maxillipedes are com-
pletely flattened, and meet in the middle as they do in the
true crabs. Such facts make the classification of the
crabs as difficult as it is interesting, but as we are con-
cerned only with British forms, it is sufficient to regard
194
THE DECAPOD CRUSTACEA. 195
as true crabs the forms showing the characters mentioned
above, Atelecydus being excluded because of the long
antennae.
Of the true crabs we shall consider here only three
families, into two of which most of our British forms
fall.
The first family is that of the spider-crabs, or triangular
crabs, as the Germans call them. There is generally no
difficulty in recognising at once the British members of this
family. Its scientific name (Oxyrhyncha) refers to the
pointed rostrum which forms the anterior angle of the
three-cornered carapace. The popular name of "spider"
refers to the way in which the small body is suspended on
the long spidery legs. Spider-crabs differ, however, very
markedly from their terrestrial namesakes in regard to
their movements; far from being agile, they rival the
historic tortoise in the slowness and deliberation of their
methods of progression. Whether the sea-grass grows
beneath their feet or not, it is impossible to say; but it
certainly does grow freely on their backs, most of them
carrying about with them a perfect forest of weeds and
sea-firs.
Our largest spider-crab is Maia squinado, the great " sea-
spider," spiny spider-crab, or devil's crab of the South and
West. It is collected in large quantities as an article of
food in the South-west, and is also abundant in the Medi-
terranean, where it was well known to the ancients. The
colour is reddish brown, but in life, as in other spider-crabs,
the body is usually densely clothed with seaweed and zoo-
phytes, attached by means of numerous bristles. The
carapace is ovoid in shape, and prolonged anteriorly into a
bifid rostrum with diverging horns. Besides the covering
of bristles, its surface is furnished with numerous tubercles,
and is strongly spinous at the margins. As in crabs in
general, the lowest joint of the stalk of the antenna is
firmly fused to the carapace. The abdomen is seven-jointed
in both sexes. The carapace may attain a length of eight
inches, and then would be about six inches broad, the legs
having a span of fifteen inches. If specimens both of this
crab and of the stone-crab (Lithodes maia, p. 187) can be
obtained, it will be found a very useful exercise to contrast
196 LIFE BY THE SEASHORE.
the two, noting the superficial points of resemblance, and
the real points of contrast. Unfortunately the two are not
likely to be both found in the same locality.
The next form is one which is not edible and has therefore
no common name. This is unfortunate, because it is in
some places extraordinarily common, almost as common as
that ubiquitous form which has appropriated the name of
"shore crab" par excellence. This is Hyas araneus (see
Fig. 55), the common spider-crab of the East Coast.
Abundant as it is, it is not a form often seen except when
searched for, and to very many people is known, if known
at all, only by the dead specimens flung on the beach after
storms. Nevertheless, in the right places one may find a
dozen large living specimens in the course of half an hour.
What are the right places ? is the question naturally asked.
Two localities I have always found specially productive.
First, deep rocky pools, preferably with overhanging edges
densely overgrown with the finer kinds of weed and with
zoophytes, whose waters never completely drain away, even
at the lowest tide. Secondly, those beds of rounded boulders
overgrown with Irish moss and red seaweeds, which are
sometimes exposed for a short time at low spring tides.
In such places the common spider-crab is generally abundant,
but I have never found it so in places where there was not
abundant moisture, and a dense growth of red seaweeds,
zoophytes, and sponges. Similar growths also cover the
back of the crab, and often conceal most of the peculiarities
of structure. Your specimens are not likely to live very
long in captivity, and while they live are often of more
interest on account of the delicate zoophytes they bear on
their backs, than because of their own habits, which are
chiefly interesting because of their profound leisureliness.
When they succumb to the injurious effects of their new
surroundings, they may be carefully cleaned and the structure
made out.
The process of cleaning is best accomplished by picking
off the encrusting weeds bit by bit with forceps. As you
do so you will find that they are attached by hook :d hairs
of remarkable appearance, which cover the surface of the
body, and are often very conspicuous in the dried specimens
found upon the beach. The hairs are of very considerable
THE DECAPOD CRUSTACEA.
197
interest to those who care about the problems of evolution.
Not only are they well adapted for their function of bearing
the spider-crab's "forest of Dunsinane," but the crab itself
actually attaches weeds and zoophytes to them. When the
hairs are removed the carapace will be seen to be covered
with the numerous tubercles so characteristic of the spider-
crabs in general. It is dull in tint, inclining towards red
on the upper surface, young and small specimens being
often very distinctly red in colour.
The general points named above having been made out,
we may proceed to consider the special characteristics of
structure.
Fio. 55.—Hyas araneus, the common spider-crab. The coating of
hairs is only indicated.
The carapace is broad, elongated, and triangular, only
slightly arched, and prolonged anteriorly into a bifid
rostrum, whose converging halves are flattened above and
deeply hollowed beneath. Immediately behind the orbit
there is a very characteristic spear-shaped process. The
abdomen is seven-jointed in both sexes. In large speci-
mens the carapace may have a length of over three inches,
and a breadth of over two. In such a specimen the legs
would be over five inches long. The specimens ordinarily
found on the rocks are, however, likely to be smaller than
this.
198 LIFE BY THE SEASHORE.
Besides Hyas araneus we have another British species —
H. coardatus — which is also very abundant, but occurs in
deeper water. It is very much smaller, and is easily
recognised by the shape of the carapace. This is suddenly
contracted behind the post-orbital processes, so that the
regularly triangular shape of H. araneus is lost. Young
specimens of this species are sometimes to be found far out
on the rocks, or among the weed flung ashore after gales,
but are difficult to distinguish from the young of H. araneus.
Indeed, some authorities deny that the two species are
distinct.
Belated to Hyas is the genus Pisa, including small, hairy
FIG. 56. — Stenorhynchus phalangium, the long-legged spider-crab.
crabs, not very dissimilar to Hyas in appearance. The two
species are too rare in Britain to merit description.
The last two genera of spider-crabs are even more spidery
than the preceding, and differ from them in the great length
of the walking legs, as contrasted with the short and thick
great claws. The great claws are especially thickened in the
male.
Under stones at low water there may be occasionally
found Stenorhynchus phalangium (see Fig 56), a representa-
tive of the first genus. The carapace forms an elongated
triangle, and is prolonged into a long tapering bifid rostrum.
The protruding eyes cannot be retracted into the circular
orbits, and are peculiar in bearing on their surface a tuft of
THE DECAPOD CRUSTACEA. 199
bristles. The rostrum is shorter than the stalk of the outer
antennae. The abdomen has six joints in both sexes, the
legs are about four times the length of the carapace, are
very slender, hairy, and usually covered with weed.
Another species occurs in deeper water.
The other genus — Inaclms — is represented in shallow
water by /. dorhynchus, found occasionally beneath stones.
The carapace differs from that of StenorhyncJius in being
sub-triangular, nearly as broad as it is long, with short, bifid
rostrum. The eyes are retractile, and the orbits elongated,
instead of circular. The species is characterised by three
spines on the gastric region of the carapace ; of these two
are anterior and one posterior, the three forming a triangle.
There is another species of larger size, but it occurs in
deeper water.
The next family of crabs is that of the Cyclometopa, or
crabs with rounded forehead. In them the carapace is
broad and arched in front and narrows posteriorly; in its
whole shape it contrasts markedly with that of the spider-
crabs. The common shore crab is an admirable and easily
obtainable example of this family, and in it the general
characters may be readily observed. Notice how very
different is the shape of the carapace from that of the
spider-crabs. The rostrum has disappeared, and in its place
we have a rounded region between the eyes known as the
forehead. From the eyes the margin of the carapace slopes
outwards and backwards, and is strongly toothed; this is
the antero-lateral margin. Next, the margin slopes inwards
and backwards, this region being known as postero-lateral ;
it is untoothed. Finally, the two postero-lateral borders are
united by a line, the posterior margin. It will be noticed
that the carapace is here broad in front, where in the
spider-crabs it is narrowest, and narrows behind where that
of the spider-crab broadens out. Most of our commonest
crabs belong to this family, and as these are largely dis-
tinguished by the shape and teeth of the carapace, it is
worth while being clear as to terminology before beginning
the study of the individual crabs.
The Cyclometopa are distinguished from spider-crabs not
only in general shape, but by the swiftness of their move-
ment s and their high intelligence. Quick at offence and
200 LIFE BY THE SEASHORE.
defence, bold in attack, swift in flight, and ingenious in
artifice, not many of the arts of war remain unknown to
them. Together with the next family, which has but few
representatives on our shores, they represent the highest
point to which the Crustacea have attained. The high
specialisation is seen in many of their structural peculiarities,
some of which we have already discussed.
The first member of the family to be considered is the
edible crab, the crab of the fisher-folk, Cancer pagurus of
science (see Fig. 8, p. 26). This familiar crab is abundant
in all the European seas, inhabiting all depths of water up
to about twenty-five fathoms. It is the object of an im-
portant fishery, especially in England, where it is more
relished than on the Continent. Though always caught on
a large scale in crab-pots in the deep water off rocks,
specimens of considerable size are nevertheless to be found
on the rocks themselves, and are there caught by the fisher
children. When exposed by the turning over of the
stones under which they lurk, they have a peculiar
habit of tucking in the legs under the broad and flattened
carapace, so as to offer only its strong surface to the
intruder.
The special characters are as follows. The carapace is very
broad and only slightly arched, the forehead narrow with
three short similar teeth, the long antero-lateral margin is
nine-lobed, while the shorter postero-lateral margin is entire
and marked by a marginal line. In the great forceps the
movable part is black, and furnished on its inner side with
blunt rounded projections. The walking legs are all similar,
the last ending like the others in a thin pointed claw. Eor
these points see the figure.
The next form is the shore crab (Carcinus mcenas), to
which allusion has already frequently been made. It is
abundant everywhere in shallow water, occurs in many
colour varieties, and is extraordinarily hardy and successful.
A charming pet, it will live long in captivity, even under
unfavourable conditions, so long as it is allowed an oppor-
tunity of occasionally quitting the water in which it is
living, and is well fed.
As to structure, the following points are worth notice.
The carapace is broader than it is long, well arched, with
THE DECAPOD CRUSTACEA. 201
three teeth in the projecting forehead, and five in the
antero-lateral margin, which is much shorter than the
postero-lateral margin. The great forceps are short, the
hand has a double keel. The terminal joint of the last
pair of walking legs is slightly expanded and flattened.
As in the Cyclometopa in general, the abdomen is five-
jointed in the male, and seven-jointed in the female.
The females will be found not infrequently carrying the
bright orange eggs attached to the hairy abdominal
appendages.
The next crab is one which is much more likely to be
found on the shore after storms than living under natural
conditions. This is Portumnus variegatus, a peculiar little
swimming crab, common off sandy shores, and easily recog-
nised at a glance by the shape of its carapace. This is
peculiar in being as broad as it is long, the antero-lateral
and postero-lateral margins being rounded instead of meet-
ing at a sharp angle. The last walking leg is, as in the
next genus, but to a less extent, converted into a swimming
paddle, the terminal joint being broad and flattened, and
the penultimate broad, rounded, and compressed. This
crab, which has no English name, is a beautiful little
creature, of mottled purplish white tint.
Finally, we come to the large genus Portunus, including
the true swimming crabs, popularly called "fiddlers" from
the peculiar motion of the last pair of legs. These ap-
pendages are completely converted into swimming paddles,
and enable the crabs to dart rapidly through the water,
thus taking on the function exercised in ancestral forms by
the tail. In general shape the fiddlers resemble the shore
crab, the carapace bearing similar teeth on its margin, but
it is much flatter and slightly different in its details. The
legs, and especially the great claws, are beautifully marked
and sculptured, the swimming crabs being alike in colour
and form singularly beautiful creatures.
The largest species is the velvet-crab (Portunus puber\
which owes its name to the dense coat of fine hair which
covers the body. It is very rare on the East Coast, but is
abundant on the South-west, where it occurs among weeds
between tide-marks.
There are numerous other species of swimming crabs,
202 LIFE BY THE SEASHORE.
among which may be specially mentioned P. depurator, the
wrinkled swimming crab, and P. marmoreus, a form with
beautifully marbled
carapace. The
species are so nu-
merous that it seems
unnecessary here to
give their distin-
guishing features,
especially as many
of them are very
local in their distri-
bution. Swimming
crabs are most fre-
quently found on
the shore thrown up
Fm. 57.— Portunus depurator, the wrinkled swimming V>v thp wavp<3 hnfc
crab. Note the shape of the last pair of legs. .Dy *8 . waves> Put
in certain localities,
especially at the edge of rocks running out into the clear
sand, it is not uncommon to find them in the living active
condition. In the sandy pools the peculiar method of loco-
motion may then be readily observed. A careful anatomical
comparison with Carcinus should also be made.
Of the last family of crabs, the Catometopa, or quadri-
lateral crabs, one example only need be described. This is
the very curious Pinnotheres pisum, the pea-crab, a very
small crab found inside the shells of many bivalves,
especially the horse-mussel (Mytilus modiolus), the oyster
(Ostrea), the cockle (Cardium), and others. The peculiar
habit has given rise to many curious superstitions, the
present being one of the first cases known of what we
now call " commensalism." The carapace is arched, almost
circular, smooth and delicate, and in the female almost
uncalcified. The males are smaller than the females, and
have a projecting forehead, while that of the females is
uniformly rounded.
This concludes our brief survey of the true crabs, which,
as we have seen, are the most specialised of the Decapod
Crustacea. We have begun our survey of the Crustacea
with the Decapods because they are the largest and most
conspicuous forms, and because they illustrate so admirably
THE DECAPOD CRUSTACEA. 203
the meaning of the evolution theory. All are constructed
on fundamentally the same plan, but display almost infinite
modification in detail. As already hinted in the preceding
chapters, it is clear that while the ancestral forms, like the
more primitive living forms, must have been free-swimming
animals inhabiting open water, the tendency of all has been
to acquire in many different ways the creeping habit, which
is an adaptation to life on the sea-bottom. Further, some
forms, like the swimming crabs, have secondarily re-acquired
the power of swimming, but accomplish this by the modified
legs, and not by the appendages of the tail as the primitive
forms do.
The motion of the more primitive swimming Decapods
is very well worth study and is of much interest. It is
perhaps most easily observed in some of the smaller prawns,
which live well in confinement and require less space than
the larger forms. When undisturbed their swimming is
the perfection of graceful and apparently almost effortless
movement. The tail-fan is kept expanded, and serves as a
rudder to alter the direction of the movements as occasion
may require ; it must also be of much use as a float, by its
extent and lightness assisting to support the body in the
water. The antennal scales, which are often large, no doubt
also perform both functions. The propulsion of the body is
effected by the movements of the anterior swimmerets,
which by their constant motion can drive the body in any
direction. Startle your prawn and you will find that it
darts backwards or sideways by the sudden flexion of the
mobile tail. It is, however, characteristic of the Natantia
that their ordinary mode of movement is gentle swimming
by means of the anterior five pairs of swimmerets. The
creeping Decapods have lost this mode of motion, and
though they retain in many cases the power of jerking
themselves backward at a sudden alarm, their ordinary
method of locomotion is a leisurely creeping. The anterior
swimmerets may be retained, or may be largely aborted,
but they are never strong enough to propel the heavy body.
Beginning with this prime distinction of habit, it is easy
to deduce the structural characters of the two sets, and it is
of very much interest to note how the minute differences
between Crustacea, such as prawn, lobster, and crab, are
204 LIFE BY THE SEASHORE.
associated with their differences in habit and mode of life.
The intimate nature of the association is often easier to
demonstrate in the Crustacea than in other groups, and
adds much of their interest to them.
Though the chapters on the Decapod Crustacea have
spun themselves out to an unreasonable length, it is not
easy to tear ourselves away from so fascinating a group.
Two subjects have not yet been spoken of, and must just
be touched on.
One of these is the moult, too interesting a phenomenon
of Crustacean life to be omitted. We have already dwelt
upon the characteristic Crustacean cuticle, or coat, and its
advantages as a defence. It has, however, the correlated
disadvantage that it periodically becomes too small for its
owner, and has to be cast and renewed. This occurs in all
Crustacea, but is perhaps best and most frequently seen in
the edible crab. If you search diligently under stones far
out on the rocks, you will certainly sooner or later come
across an edible crab in a sluggish apathetic condition.
Watch it, and you will see the whole of the shell split off
at the insertion of the legs, and thrown aside, snowing
beneath it the new coat, very bright in colour but perfectly
soft to the touch. Little by little the crab also extricates
himself from the rest of his coat, pulling his claws slowly
from their envelope, and gradually pushing the discarded
shell away from him. Pick this up, and you will find that
it is complete in every detail; not only is the covering of
every appendage (even the most minute) fully represented,
but the covering of the eyes, of the gills, nay, even the
lining of the stomach is there. Turn to your soft, helpless
crab, and you will see a stranger sight still : the crab which
has just come out of the shell you hold in your hand is
now bigger, is probably what will seem to you very much
bigger than that shell. If, as one is often very apt to do,
you have placed the crab when first seen in a bottle for
transport, you will find that what went in easily will by no
means come out without injury. The meaning of which
strange fact is that as the new coat does not stay soft for
long, the crab must hasten to get all the growing- done
possible in the short time at its disposal. But growth is
a slow process, so it distends its tissues with water to en-
THE DECAPOD CKUSTACEA. 205
sure the new shell being large enough to allow of sub-
sequent growth. Try to boil and eat a "soft" crab, and
you will speedily realise the condition of affairs. The
process of moulting in a large crab is to be counted as one
of the most impressive of the phenomena to be witnessed
on the shore, and may often be watched by a close observer.
During and after the moult the crab is absolutely helpless,
and until the shell grows hard again is at the mercy of
every foe. The crab realises clearly its 'helpless condition,
and always seeks shelter in some nook or cranny of the
rocks. Even there, however, it is not always safe, and is
attacked by members both of its own and other species,
who greatly appreciate the succulent morsel. Moulting is
in consequence a process full of risk and danger to all
Crustacea, but it is the price which has to be paid for the
advantage of a coat of armour.
Moulting occurs in all Crustacea, and many times in the
life of each individual. The cast coats of the different
species are always abundant about the shore rocks, and are
often mistaken for dead crabs. They are always interesting
and worth study, and can be recommended to those who
have scruples about killing animals for dissection purposes.
In still one other respect the Crustacea are of great
interest. This is in regard to their development, which is
markedly indirect, the young being usually very unlike the
adults. Examine a female Mysis, or opossum-shrimp (see
p. 209), with young in her brood pouch, and you will find
that the young are in most respects similar to the parents.
This is one of the exceptional cases where the development
is direct, and without distinct metamorphosis. It is other-
wise with the majority of the Crustacea. In the crabs, for
instance, the eggs are carried about by the mother only till
they hatch, and the larvae when hatched (see Fig. 92) are
very different from the mother. They are minute, trans-
parent creatures, colourless save for the eyes, with quaintly
shaped body furnished with long spines and few appendages.
Such embryos are called zoeas, and their relation to the
adult crab was for long unknown. The zoea stage of the
common shore crab is to be found in vast numbers on the
surface of the sea in autumn, but is more likely to be got
by tow-netting than in rock pools. The zoea grows and
206
LIFE BY THE SEASHORE.
moults and becomes converted into the megalopa, a form
much more like a crab than the zoea, but differing markedly
from crabs in the presence of a long, mobile abdomen,
capable of being used in locomotion. The megalopa is the
stage of transition from the free-swimming zoea, whose
habitat is the open sea, to the creeping crab, whose habitat
is the sea-floor. Its special interest lies in the fact that
while the zoea swims by means of its thoracic appendages,
as do some of the' lower Crustacea, the megalopa can swim
with its tail like a long-tailed Decapod. For a full dis-
cussion of development of the Crustacea
reference must be made to the text-
books, but the study of a living
megalopa will give you a more real and
vivid appreciation of the process than
the clearest and best description. The
megalopa stage of our common crabs
may often be found among weeds in
the rock pools.
When found, place your specimens
in a saucer of clean water, and examine
of tail and body, the with a lens. If you have obtained
ten legs, the rostrum . . ,.~, ^ , .,,
between the eyes, and specimens of different ages you will
tail SVAftereBeroSokn the no^ce now some move like a Galathea
by rapid jerks of the tail, how others
alternate between this and creeping like a crab, while others,
again, confine themselves almost entirely to the latter form
of motion. The sight is one which you will probably mark
as forming an epoch in your observations of shore animals.
The fact in itself is a
mere trifle perhaps, but
it is one of those ap-
parently trifling pieces of
observation which seem
to suddenly illumine
days of patient, but ap-
parently fruitless, study.
Later the little mega-
lopa tucks in its tail, FlQ 59._My8is stage of Norway lobster (Neph-
UnderCOeS Certain minor rops). Notice that the biramose legs of the
°. , i larva are in process of transition into the
alterations, and becomes uniramose legs of the adult. After Sars.
THE DECAPOD CRUSTACEA.
207
converted into the young crab. This is merely one, and by
no means one of the most complex, of the life-histories of
the Crustacea, but it is one which can generally be easily
studied. In Fig. 59 another larval stage, one which is
common among long-tailed Decapods, is represented. Its
great interest lies in the resemblance to the opossum-shrimp,
especially as regards the shape of the legs.
KEY FOE, THE IDENTIFICATION OF CRABS DESCRIBED
IN THIS CHAPTER.
Order DECAPODA.
II. REPTANTIA (see p. 163), Brachyura, or crabs in the narrow
sense, including forms with short antenna, which, like the eyes and
an tommies, are placed in sockets.
Carapace triangular with \ 1. Fam. Oxyrhyneha
rostrum, legs long . / (spider-crabs).
Carapace broad, arched
in front, and narrow
posteriorly
dl
w V 2.
Fam. Cyclometopa.
1. Fam. Oxyrhyneha.
Chelipeds not
markedly dif- ^
ferent from
other legs .
Chelipeds much
shorter and
stouter than
other legs, 1
which are
very slender
Rostrum with diver- / Maia
. \
gent horns— Maia
Rostrum with conver-
gent horns, hollowed \
Beneath-Jfyo*
squinado, with
prickly body.
In H. araneus the cara-
Paf? ™ "oi contracted
behmd the P~t-orbital
. T Processes
I In H. coarctalus it is con-
tracted behind these.
Carapace sub-triangu-
lar, nearly as broad
as long, orbits elon-
gated— Inaclius
Carapace an elongated
triangle with long
rostrum — Steno-
rkynchus
Between tide-marks I. do-
rhynchus, with three
spines on the gastric
region, is the only
species found.
Between tide-marks oc-
curs S. phalangium,
in which the rostrum
is shorter than the
stalk of the antennae.
208
LIFE BY THE SEASHORE.
2. Fam. Cyclometopa.
a. Walking legs all with thin\ Carapace with nine lobes— Cancer
pointed terminal segments/ pagurus, or edible crab.
long as \ P. variegatus is only
rtumnus J species.
Last segment of ^
fifth legs only ! Only species is
expanded — j 0. mcenas.
Carcinus . J
Penultimate seg-^ ,.-
ment expanded I m^ SP6C1£S> e^'
as well as last f ^-P^e^Pmar-
, -Portunus J moreus> etc'
3. Fam. Catometopa.
v/ai ct ucbL/c a»o
broad — Po
Last pair of
walking legs
with ex--
panded tin-
like ending.
Carapace
broader -
than long
SUMMARY CLASSIFICATION OF DECAPOD CRUSTACEA.
I. Natantia — swimming forms with compressed bodies and functional
swimmerets ; e.g. prawns and shrimps (Chap. VIII. ). Fam. Carididte.
II. Reptantia — creeping forms, sometimes with long tails (Macrura),
e.g. lobster and crayfish ; sometimes with inturned tails (Brachyura),
e.g. crabs ; intermediate forms also occur. The following families
are included : —
(1) AstacidjB, lobster and Norway lobster.
(2) Palinuridse, rock -lobster.
(3) Porcellanidse, the lobster-like Galatheas and the crab -like
porcelain-crabs.
(4) PaguridjB, the hermit-crabs.
(5) Lithodidae, the stone-crab, with large incompletely calcified
abdomen.
(6) Corystidse, the masked crab and the circular crab ; the latter
is sometimes placed in the family Cyclometopa.
(7) Oxyrhyncha, the spider-crabs, apt to be confused with the
stone-crab.
(8) Cyclometopa, the shore crab, swimming crabs, and edible crab.
(9) Catometopa, the pea-crab, and a few other southern forms.
NOTE ON DISTRIBUTION.
Generally speaking it may be said that the crabs increase in number
'in the British area as one passes southward. Exceptions to this rule
are the interesting stone-crab, a northern species, and the two species
of Hyas. These last are not absent from the South-west of England,
but they are not nearly so abundant there as in the North. On the
other hand, the rocky coasts of Devon and Cornwall produce Maia
squinado, especially abundant in Cornwall, the velvet-crab between
tide-marks, and a number of other interesting and peculiar forms of
which no mention has been made here. The shore crab, the edible
crab, the numerous species of Portunus apart from the velvet-crab,
occur at all parts of the coast.
CHAPTER XL
SOME OTHER CRUSTACEA.
The opossum-shrimp and its allies — Sessile-eyed Crustacea — Structure
of Isopods — The Amphipoda — Characters and habits of sand-
hoppers— Structure of Caprella — The lower Crustacea — Structure
and habits of acorn-shells and barnacles— Crustacean parasites —
Sea-spiders — Their zoological interest.
WHILE searching for shrimps and prawns, you are
certain sooner or later to encounter some little shrimp-
like creatures of singularly beautiful appearance. Far out
on the rocks, in clear pools floored with silver sand, you
will find them swimming with outspread eyes, and bodies of
crystal clearness. Turn to the shallower pools lined with
green weed and you will find similar forms, but here of the
same pale green as their surroundings. Again, if you push
aside the great blades of
Laminaria, you will see dart-
ing out from beneath them
in shoals the same little crea-
tures, but now of a deep
brown tint. This is My sis
flexuosa, sometimes called
chamceleon from its Protean
tints, and chain seleon-like in Flo. eo.-Opossum-shrimp (Mysis frx-
its power of colour change.
a -t, • , t
bwitt swimmers as they are,
they are easily caught, and, though difficult to keep in an
aquarium, they are well worth study. Collect a good
handful, and put them with plenty of clean water in a glass
jar. You will then have no difficulty in seeing that in
many respects they resemble shrimps and prawns very
P 209
uosa). Female specimen, showing brood
pouch between the posterior legs.
210 LIFE BY THE SEASHORE.
closely (Fig. 60). Like them they have an anterior region,
not obviously segmented and covered by a shield; a tail
region divided into segments and ending in a powerful
tail fin, and long feelers colourless in the living animal,
and bearing a large scale or squame at their bases. They
differ from shrimps, however, in that they seem to have
far more legs, and in that many of them have a pouch
attached to the posterior legs, as is shown in the ac-
companying figure. These are the females, and when
adult the pouch will be found to contain developing eggs.
The eggs are placed in the pouch when laid, and are
carried about by the mother. The members of the order
to which Mysis belongs are all very good swimmers, well
adapted for life out in the open sea, but, as happens with
so many marine animals, the females come inshore at the
breeding season. This is partly, no doubt, for the sake
of the young when hatched, but probably, in other cases,
because the weight of the eggs or young must greatly
diminish the swimming power of the mother. Your speci-
mens are almost certain to be all females, and a very brief
experience will be sufficient to teach you that the large
mature specimens are so sensitive to unfavourable condi-
tions, that they will not readily live in confinement. In a
very short time they lose their lovely tints, become dull and
opaque, and drop to the bottom of the jar. You will find
that this delicacy of egg-carrying females is common in the
Crustacea, and it is profoundly interesting, for it shows how
great must be the advantage of the habit of carrying about
the eggs, if it can persist against such heavy odds. There
are, indeed, few subjects more interesting than the reproduc-
tive phenomena of shore animals.
Before proceeding to the examination of your dead
specimens, you should examine the living ones under a
lens in a watch-glass filled with sea-water. Whatever be
the prevailing tint, and it varies much, you will find the
dorsal surface covered with the same beautiful branched
pigment cells seen in the shrimp. They are here black in
colour and are often arranged segmentally, one for each
segment. This is indicated in the figure. The rest of the
body may be green, or brown, or transparent, but the
anterior region is almost always delicately suffused with
SOME OTHER CRUSTACEA. 211
pink, especially about the antennae. You will notice also
the large, very movable eyes, usually outspread laterally,
but capable of much freedom of movement. Also the
curious bend in the middle of the body, which gives rise
to the name flexuosa, and has at times almost the look of a
deformity. The larger specimens will be found to be over
an inch in length, but many are much smaller. With the
lens there is no difficulty in making out that there are eight
pairs of legs, very similar to one another, and that all of
them consist of two branches. It is on account of this and
of some other characters that Mi/sis is included in the order
Schizopoda, or "split-footed," as contrasted with the Deca-
poda, or Crustacea with ten legs, already described. The
Schizopods are even more purely swimmers than the Natantia
among Decapods; they have no walking legs, strictly speaking,
and their eight pairs of thoracic legs resemble one another
very closely.
The My sis described above is by far the commonest
member of its order on the shore, for the great majority
of its relatives live in the open sea, but there are a few
other nearly related forms which occur more sparingly along
with Mysis flexuosa^ or are occasionally found far out at
exceptionally low tides. All these belong to the family
MysidaB, and resemble one another so closely that their
discrimination requires some care. Those who are fond of
species work will find Mysidae peculiarly fascinating, while
others are recommended to rest content with Mysis flexuosa.
We shall describe one or two representative species only.
To begin with the large Mysis flexuosa. We have already
seen that it belongs to the order Schizopoda; it further
belongs to the family Mysidae because of the following
characters. Its eight pairs of thoracic limbs are similar
but not identical, for the first two have a masticatory
process at their base, and the first has also a flat vibratile
appendage. Some of the posterior thoracic limbs bear
somewhat similar appendages, which here, however, are
apposed so as to form the brood pouch in the female. Gills
are entirely absent. There is much difference between the
sexes, especially as regards the abdominal appendages, for
these, except the last pair, are well developed in the male
and rudimentary in the female. The inner branches of the
212
LIFE BY THE SEASHORE.
tail fins bear round auditory organs (o in Fig. 61), for My sis
has ears in its tail. The last five segments of the thorax
are more or less movable, not fused together as in shrimps.
All the Schizopods you are likely to find on the shore
belong to this family. It is divided into a great number of
sub-families, chiefly on account of the varying structure of
antennas and telson, and the sub-families contain numerous
genera, but it will be sufficient for our purpose to retain the
genus Mysis in its old sense. For further details reference
should be made to Canon Norman's papers (see books of
reference at end).
If you have succeeded in laying out the thoracic limbs
FIG. &1.—A, head, and B, part of tail of Mysis. A shows
the eyes (e), the scale (s), and part of the flagellum of
the right antenna, and the two antennules (a). B shows
the telson (t)and the left terminal swimmeret, with the
ear (o) in the inner branch. After Bell.
of Mysis flexuosa in a row, and demonstrating the other
characters of the family to your satisfaction, you will find
no further difficulty in studying its specific characters.
Besides the points already noted it is distinguished by the
following peculiarities. First, the length of the antennal
scale (s in Fig. 61). To see this clearly, float your dead
Mysis in water — the lid of a white ointment jar makes a
good dissecting dish — and observe under a lens. You will
then see clearly the antennae with their long flagella and
stout scales (s), and the shorter antennules (a), each with
a three-pointed stalk and two feelers. In Mysis flexuosa
you will find that the scale of the antennas is narrow and
very long, twice as long as the stalk of the antennules ; it
is without bristles (setae) on its outer margin, and that
margin terminates in a distinct spine ; all these points are
clearly shown in Fig. 61, A, which also shows the eyes (e).
SOME OTHER CRUSTACEA. 213
Turn now to the telson, or last segment of the body, and
you will find that this is deeply cleft at its tip (t in Fig. 61),
and bears twenty-one to twenty-seven spines on either side.
Note at the same time the curious ear (o) in the swimmeret.
Minute points of no importance you will probably think
these, but your respect for them will probably increase
when you examine specimen after specimen and find them
constant, true indices of those subtle undefinable characters
which make up the species M. flexuosa. There are few
more striking illustrations of what is meant by the con-
stancy of nature, than the characters of nearly related
species like those of the genus Mysis. In many cases the
species is defined by the relative size of two structures, or
by the number of spines borne by an organ. What invisible
force is it that limits the growth of the antennal scale in
M. flexuosa when it is twice as long as the stalk of the
antennule, and allows that of M. vulgaris to grow till it is
four times as long? Why should the latter never have
more than twenty-five spines on its telson when the former
may have twenty-seven ? When these and similar questions
crowd upon you, then the fascinations of species work will
become clear. One would not of course deny the existence
of variability here, as elsewhere, but very little species work
will serve to convince you of the essential constancy upon
which the variability is superimposed.
The characters given above will be found sufficient to
identify M. flexuosa. Another species, smaller in size and
much less common, may be sometimes found with it. This
is M. vulgaris, which, though occasionally found in rock
pools, is typically an inhabitant of tidal rivers and estuaries.
It is most likely to be found in the pools left by the ebbing
tide on those mud flats which in Northumberland are called
"slakes"; or sometimes occurs in myriads at the edges of
tidal rivers. This species may be recognised by the fact
that the antennal scale has no spine, is furnished with setse
all round, and is four times as long as the peduncle of the
antennules. The telson is not cleft, and ends in four spines.
There are a great many other species of Mysis found
more or less commonly on our shores, but for these reference
must be made to Canon Norman's papers. I shall mention
one more only, which I have found to be not infrequent on
214 LIFE BY THE SEASHORE.
the East Coast, and which is interesting on account of its
colour. This is My sis lamornce, a delicate little creature
not much more than one-third of an inch long, and wholly
or partially of a bright red colour. It is often in large
part perfectly transparent, but is suffused with scarlet and
bears bright scarlet eggs. It may be found under stones
far out on the rocks, and may be recognised by the very
large eyes borne on short stalks, and by the fact that the
antennal scale is the same length as the peduncle of the
antennule, and that the telson is cleft for one-quarter of
its length, without spines in its upper portion, and furnished
distally with six to twelve at either side. The distribution
of this species in Europe is wide, for it ranges from Lofoten,
on the coast of Norway, through the Mediterranean to the
Black Sea. The colour is also worth notice, for bright red
is common in deep-sea Crustacea and in pelagic forms, but
is rare in those found near the shore.
In the above species the specimens found are much more
likely to be females than males. When found the males
may be recognised by the absence of the brood pouch, the
slimmer form, and the nature of the swimmerets. The
third and fourth of these are much better developed than
in the females, the fourth being furnished with a long
many-jointed whip-like structure.
We shall not here describe any other of the British
species of Mysis, but a not uncommon form which is now
referred to another genus is worth notice. This is Siriella
armata, found in rock pools in company with Mysis
flezuosa, but distinguished by its smaller size and more
delicate appearance. It is referred to a different genus
because the outer branch of the last swimmerets is divided
into two joints, the carapace is prolonged anteriorly into a
long rostrum instead of ending in a blunt point, and all the
swimmerets of the male except the first are well developed,
some of them being furnished with a curiously coiled pro-
cess. In the species named the rostrum is as long as the
antennal scale, both being slightly shorter than the stalk of
the antennules. The telson is very long, not cleft, slightly
constricted at its base, its margin being furnished with a
few short spines placed between longer ones. This species
is difficult to distinguish from other closely related species
SOME OTHER CRUSTACEA. 215
of the genus, but it will be found that the telson ends in
four minute spines, separated by two setae from the large
lateral spines.
The above may serve as examples of our British Mysidse,
and will show how relatively small are the differences which
separate the species and even the genera, compared with
the differences between the sexes. When to this is added
the fact that many of them only appear sporadically and
locally on our coasts, it will be readily understood that not
only have males and females been commonly referred to
different genera, but also that the different specialists in the
group have held very various views as to what should con-
stitute generic or specific distinctness. Consequently there
is great confusion as to the names of the different forms.
For example, a form described in Bell's Crustacea under the
name of TTiemisto brevispinosa appears to be only the male
of My sis flexuosa.
The other Schizopods lie somewhat outside our range, for
they inhabit the open sea. The interest of the order as
a whole lies in the general resemblance to the Natant
Decapods, and the detailed similarity to the larvae of many
of the Decapods (see Fig. 59). The beauty of the form
and colour, the activity, the frequent extraordinary abund-
ance of individuals, and the habit of swimming in shoals
should also be noticed.
The orders Decapoda and Schizopoda, whatever their
other differences, both include forms having stalked eyes
and a dorsal shield or shell, but there are other shore
Crustacea of considerable size and complexity in which the
eyes are sessile and the dorsal shield is absent. These fall
into two sets: (1) the Isopoda, forms more or less like the
common "slater," or wood-louse, with flattened bodies, and
(2) the Amphipoda, or sand-hoppers, whose bodies are com-
pressed, and who usually have six abdominal legs, three
directed forwards and three backwards. We shall not
enter into either of these orders in detail, for their mem-
bers are not as a rule attractive to most people, and are
often difficult of identification.
As an example of the Isopoda we may take a not un-
common and somewhat interesting form known as Idotea
tricuspidata. It is usually found clinging to weed, especially
216 LIFE BY THE SEASHORE.
Fucus, by its numerous sharp-clawed legs, and is extra-
ordinarily variable in colour. Usually brown or brownish,
it is sometimes tinted with yellow, red, or green, sometimes
spotted or striped with darker colour. The length varies
from three-quarters of an inch to an inch or more, and the
flattened body makes the little creature very inconspicuous.
As in other members of the order, the number of rings
in the body is primarily the same as in Decapoda, but the
body is distinctly divided into three regions, of which the
thoracic is the most conspicuous. The first thoracic segment
is fused to the head, so that the thorax
appears only to possess seven rings ; the
abdominal segments are in part fused.
The head bears two pairs of antennae,
consisting of simple flagella; of these
the outer are half as long as the body.
There are seven pairs of similar thoracic
legs, corresponding to the seven free
thoracic segments. Over the surface of
the abdomen there is a triangular tail-
shield which covers all except the two
first rings. The five anterior abdominal
FIO. 62.— idotea tricuspi- appendages are converted into thin respi-
data. In part from Bate r i A ,-, • ,1 •<• .
and Westwood. ratory plates, the sixth pair forms two
strong valves which cover over these
thin plates. In life the valves are in constant motion,
opening and shutting to facilitate the passage of water
over these curious breathing organs, which replace the gills
of the Decapods. A careful dissection of Idotea is easily
made, and will be found very profitable.
The Amphipoda are most typically represented by the
sand-hoppers, which swarm everywhere over the damp sand,
assembling in myriads about decaying substances thrown on
the beach, and perforating the dry sand above high-tide
mark in all directions with their burrows. They are the
great scavengers of the shore, sometimes within a few hours
reducing dead birds of considerable size to the condition of
skeletons. On the rocks their place is taken by other forms
equally abundant, and of similar habit.
The common sand-hopper is Talitrus saltator. Like its
allies, it presents a general resemblance to the Isopods, but
SOME OTHER CRUSTACEA. 217
differs in the compressed shape, and in the fact that the
thoracic appendages bear breathing organs, while the
abdominal are used for swimming and jumping. As special
characters are to be noticed the absence of the anterior
antennae (antennules), and the great length of the posterior.
Of the seven thoracic legs the first pair are larger than the
second. The first three abdominal appendages are turned
forwards, and are used for swimming; the last three are
turned backwards, and are used for jumping. The colour,
as everyone knows, is a peculiarly glassy yellowish white, or
occasionally a dark dirty tint.
Under stones in the rock pools the true sand-hopper is
replaced by swarms of another little creature of similar size.
This is Gammarus locusta (see
Fig. 63), the great scavenger of
the rock pools, as the sand-
hopper is of the shore. It
is easily distinguished from the
latter by the fact that the an-
terior antenna (antennules) are
well developed, and have two
filaments each. When suddenly
uncovered by the removal of the
Stone Under which it has been FIG. 63.— Gammarus locusta. Note
i • /-v i •! •, the two pairs of feelers and the
lying, GammarUS exhibits a number of legs, of which there
curious sidelong movement, which J£™en pairs belonging to the
seems to combine the maximum
effort with the minimum result. If you shake out a bunch
of weed in water, however, you will find that the little
animals can swim swiftly enough.
Another somewhat interesting shore Amphipod is Amphi-
thoe podoceroides, which makes nests of weeds under stones.
The nests are often of considerable length, and very neatly
woven, and are a source of much disappointment to many a
young shore naturalist. The nest is found with joy, and
torn open by careful fingers, eagerly expectant of a prize,
when instead out shoots the Amphithoe, or oftener, perhaps,
two of them, male and female together. Why they should
be a disappointment perhaps is not obvious, but it is an un-
doubted fact that most people cannot carry their enthusiasm
as far as Amphipods. The species named reaches a length
218 LIFE BY THE SEASHORE.
of about three-quarters of an inch, and is usually olive-
green in colour, minutely speckled with black spots. The
inferior antennas, or antenna? proper, are shorter and stouter
than the superior, and the last pair of jumping legs are
furnished with hooks.
Before leaving the Amphipods one other set of forms
must be noticed. These, typically represented by the
species of Caprella, are very different from the rest, being
both curious and beautiful, but unfortunately not very
abundant or very easy to find. Study closely a rock pool
lined with red seaweed, and you may see a slender thread-
like creature, probably rather over half an inch in length,
which attaches itself to the weed by its long back legs, and
sways back and forwards in the water. The tint is exactly
that of the weed, and the swaying motion so similar to that
produced by currents of water, that it is exceedingly
difficult to distinguish the little organism. Disturb it, and
it will swim rapidly through the water by suddenly con-
tracting and straightening the body, or travel over the
surface of the weed by alternately fixing the opposite ends
of the body like a "looping caterpillar." It is unfortunate
that we have no common English name for these interesting
and curious little creatures. One or two should be taken
home for careful exam-
ination under a lens.
It will then be found
that the second thoracic
segment is fused to the
head as well as the
first, so that there are
only six free segments.
In the figure the first
and sixth are num-
bered. The abdomen
Fio. 64.— Caprella Unearis. The letters are (ttb) is greatly reduced,
explained in the text. and at most bearg mQTQ
rudiments of appendages. The head bears two pairs of
similar antennae, and on account of the fusion of segments
the first pair of legs appears to arise from it. The second
pair of legs is large and sub-chelate, as in some shrimps —
that is, the last segment can be bent down on the second
SOME OTHER CRUSTACEA. 219
last, to form a kind of forceps. There are no true append-
ages on the next two segments, but merely two expanded
respiratory plates (rp). In the mature female these seg-
ments also give rise to four incurved lamellae, which together
form a brood pouch containing the transparent eggs. The
last three thoracic segments each bear a pair of well-
developed legs directed backwards. The abdomen (ab) is
reduced to a mere knob. There are several species which
are not very easy to distinguish from one another ; the
commonest is, perhaps, Caprella tuberculata.
We have given very few examples of these sessile-eyed
Crustacea, because they are not of great general interest, and
those who are desirous of pursuing the subject further will
find Bate and Westwood's British Sessile-eyed Crustacea a
comprehensive and readily accessible work.
The Amphipods and Isopods do not complete the Crus-
tacea, for there are in addition a considerable number of
other orders, all comprised in the Entomostraca or lower
Crustacea, as contrasted with Amphipods, Isopods, Schizo-
pods, and Decapods, which are all included in the Mala-
costraca or higher Crustacea. The Entomostraca are usually
of small size, consist of a variable number of segments, and
have no gizzard or gastric mill. A large number of them are
parasites, often very degraded parasites, and many others
are water fleas, such as may be found in any pool. The
latter form an important part of the food of fishes and other
marine animals, but cannot be considered in detail here.
Of the Entomostraca we shall consider only four common
examples, all belonging to the order Cirripedia.
Our first example is, perhaps, the most abundant animal
of all on many shores. This is Balanus balanoides, the
common acorn -shell, often so abundant as to whiten the
shore rocks, and also covering shells, posts, and almost every
available surface within tide-marks. At low tide the little
white cones look dead and desolate enough ; but if you
watch a mass of them exposed to the action of the incoming
water, you will find the scene changed indeed. As the
white water breaks foaming over the rock, and trickles off
more slowly, you will see each tiny shell open and protrude
a delicate fringe, which opens and closes in frantic haste as
if its owner were aware that the water would soon be gone.
220 LIFE BY THE SEASHORE.
There are few more beautiful sights than a rock covered
with acorn-shells exposed to dashing breakers. The moist
oxygenated air seems to excite the little creatures, and they
open almost before the first drops touch them, and keep up
their vigorous fishing till the last drop trickles off the rock.
The sight of those myriads of little fans in action is one not
soon to be forgotten. The acorn-shells have another interest
in their history. They were long thought to be molluscs,
and it was not till, in 1830, their development was fully
worked out by J. Vaughan Thompson, that their true
position was understood.
The details of the anatomy are somewhat beyond our
scope, but we may notice that the segmentation of the
body is quite indistinct, and that it is clothed in a fold of
skin, which secretes a shell of limy plates. The limy plates
consist of a ring fixed to the rock and inclosing the body,
and a movable lid or operculum, formed of separate plates,
which open to allow the protrusion of the six pairs of two-
branched jointed feet. The commonest species is Balanus
balanoides, but there are several others on our shores.
An even more curious creature is the related ship-barnacle,
Lepas anatifera, occasionally found on wreckage on the
shore. It has a long fleshy stalk, usually several inches in
length, bearing at its tip a complicated whitish shell, and
attached to floating wood by the other end. The shell is
formed of five separate plates, and in life is continually
opening at its tip to allow the six pairs of jointed legs to
be protruded. The ship-barnacle has some antiquarian
interest, because it was thought by the old authors to have
some connection with the Bernicle Goose. The old herbalist
Gerard described the young geese hatching out of the
barnacles under the influence of sunlight, but though there
are very many strange things about these curious creatures
there is nothing quite so strange as this.
Two more of the lower Crustacea must be briefly described,
not because they can be studied with any degree of success,
but because they are certain to be encountered. These are
two parasites, which are true Crustacea in their youth, but
in adult life display no trace of Crustacean characters. One,
PeMogaster paguri, is very common on the hermit-crab, the
other, Sacculina carcini, is found on the abdomen of the
SOME OTHER CRUSTACEA. 221
shore crab, or occasionally on the swimming-crabs. If you
keep hermit-crabs even for a short period in a crowded
collecting-bottle, they very speedily show their discomfort
by quitting their shells. As they trail the lank abdomen
behind them, you will notice in one or two cases a large
rounded cylindrical body of yellowish colour attached to its
under surface. This is the parasite, and its only distinct
structural peculiarity is the reproductive orifice at the broader
end of the cylinder. Dissect a dead hermit, and you will
find ramifying through its abdomen a system of fine roots,
by means of which the parasite feeds itself. It has no
mouth, no alimentary canal, no appendages, and is chiefly a
mere sac of eggs. Much less conspicuous is the rounded
Sacculina on the abdomen of crabs, for it is partly concealed
by the inturned tail of the crab. Its structure is similar,
except that the reproductive orifice is in the middle instead
of at one end.
One other small group may be considered here in con-
nection with the Crustacea, for though its littoral members
are few in number, they are very
common, and the group itself is one
of great interest. This is the Pycno-
gonida, or sea-spiders, including small
long-legged, spidery creatures com-
mon under stones on the shore. Two
are very common; one (Pycnogonum
littorale, see Fig. 65) occurs under
slightly muddy stones, and is a dirty FIG. 65.— Sea-spider (Pycno.
yellowish flattened creature with four 9°num morale^
pairs of stout knobbed legs, and a massive trunk prolonged
forwards into a large cone-shaped proboscis, and bearing
four brownish eyes on its dorsal surface. It is the most
sluggish and leisurely of creatures, moving, when it does
move, by slowly lifting one after the other its eight clawed
legs. The other common form is more attractive both
in tint and in shape. It is bright pink in colour, with
long slender legs about three times the length of the
body, and ending in long claws. In addition to the eight
legs which it possesses in common with the preceding, it
has a pair of short chelate appendages about the mouth,
while the male, as in the preceding form, has two very
222 LIFE BY THE SEASHORE.
slender appendages used for carrying the eggs. This pretty
little creature rejoices in the dreadful name of Phoxichili-
dium femoratum, and is to be found not uncommonly under
stones or clambering over weeds between tide-marks.
Other forms often occur in numbers on weeds cast ashore
by storms. These are species of Nyiftphon, white or pinkish
in colour, and not unlike the last in appearance, but with
even more slender filiform legs, three or four times as long
as the body. They differ from the preceding in having, in
both sexes, three appendages in front of the first pair of
legs. Beside the mouth, as in Phoxichilidium, are two
small chelate limbs, behind these two pairs of slender
appendages, the first with four or five joints, the second
with nine. The first two pairs of appendages are used in
connection with food catching; the third in the male, as
in other Pycnogonids, carries the eggs, while in the female
they are functionless. The remaining four pairs function
as organs of locomotion in both sexes. This is the typical
condition of the appendages, from which the common
Pyenogonum littorale diverges widely.
It is hardly necessary for us here to consider in detail the
special characters of these curious creatures, but we may
just note that their interest lies in great part in the fact
that their systematic position is very uncertain. The body
and limbs are segmented; they are undoubted Arthropods,
but the body is divided into three regions — unsegmented
proboscis, trunk of four segments, and unsegmented abdomen,
— and there are no antenna? or gills ; a connection with the
Crustacea is therefore not obvious. Of terrestrial Arthro-
pods spiders seem to resemble them most in the absence of
antennae and the presence of four pairs of legs, but spiders
have two appendages only in front of the first walking leg,
and sea- spiders may, as we have seen, possess three. Their
position is thus wholly doubtful, and the question of their
relationships unsolved.
One other point of interest is found in the fact that, as
in the sea-horse among fishes, it is the male and not the
female which carries about the unhatched eggs. In the
Crustacea it is of course the females alone which do this.
Insignificant as the sluggish sea-spiders may seem to be,
they are thus not without points of interest. Nor are they
SOME OTHER CRUSTACEA.
223
always small, for a magnificent form of large size occurs in
the Arctic Ocean, and with the Gorgon-headed starfish
(Asteroplnjtori) and some other beautiful creatures, rewards
the zeal of the investigator of that chilly sea.
KEY FOR IDENTIFICATION OF MYSIM1.
Order SCHIZOPODA. Crustacea with eight similar pairs of bi-
ramose thoracic legs.
Fam. MYSIDJB. Gills are absent. Auditory organ present in the
tail.
Antennal scale twice as long
as peduncle of antennae.
Telson cleft — M. flexuosa.
Antennal scale three or four
times as long as peduncle.
Telson entire — M. milgaris.
Antennal scale same length
as peduncle. Telson short,
cleft for one-quarter its
length, upper half without
spines — M. lamornce.
Outer branch of uropods \
one-jointed, and fur- I •,, .
nished with bristles on f Mysis
its outer margin . . j
Outer branch of uropods
two-jointed, first joint
with spines, but not
bristles, on its outer
margin
- Siriella
Antennal scale same length
as rostrum — S. armata.
OUTLINE CLASSIFICATION OF LITTORAL CRUSTACEA.
Sub-class MALACOSTRACA. Body with nineteen segments.
Section A. Forms with stalked eyes.
Order 1. DECAPODA (see p. 208).
Order 2. SCHIZOPODA. Eight pairs of similar biramose feet.
Fam. MYSID.E. Auditory organ in tail.
Section B. Forms with sessile eyes.
Order 1. ISOPODA. Body flattened, appendages of abdomen,
respiratory plates.
Only one form, Idotea tricuspidata, has been described
in the text.
Order 2. AMPHIPODA. Body compressed, abdomen usually with
six pairs of legs.
In the text three sandhopper-like forms have been
described, as well as a member of the family
Caprellidse, in which the abdomen is greatly
reduced.
224
LIFE BY THE SEASHORE.
Sub-class ENTOMOSTRACA. Body usually with few segments.
Order CIRRIPEDIA, including parasitic (Sacculina), and degenerate
sedentary forms (Balanus).
There are very many other kinds of Crustacea, especially of Ento-
mostraca, not alluded to in the previous chapters on account of their
small size, or rarity, or absence from the shore.
PYCNOGONIDA, OR SEA-SPIDERS.
A small group of uncertain affinities. Four pairs of walking legs,
abdomen rudimentary, without appendages.
No other appendages
except four pairs of
legs in female, male
with slender egg-
bearing legs .
Chelipeds present near
mouth, in female no
other appendages
except the legs, in
male egg - bearing
legs as before
Chelipeds and two
other pairs of appen-
dages near mouth in
both sexes
Legs stout and re- /-Colour yellowish
latively short — •! white — P. lit-
Pycnogonum . ^ lorale.
( Legs about three
Legs very slender I times as long as
and long — Phoxi- \ body. Colour
chilidium . . \ pink — P. femora-
turn.
•
Legs very long and
slender — Nym-
phon .
ver well definecL
CHAPTER XII.
MOLLUSCS, OR SHELL-FISH.
General characters of the Mollusca — An outline classification— The
Chitons, their habits and structure — The common limpets — Forms
with coiled shells — Their general characters — Tops and periwinkles
— Species of periwinkles — Some allied forms — Carnivorous forms —
Whelks, purples, and their allies — Their egg-capsules and develop-
ment— The cowry.
HHHE Mollusca form a very large group, including animals
_L which are usually well defined and easy to recognise.
The fact that most possess a shell which is easy to study
and to preserve has rendered them general favourites among
those interested in shore animals. Probably, indeed, most
people have at some period of their lives made collections
of shells ; all know how beautiful in form and colour they
often are. Interesting as shells are, however, it cannot be
denied that as a whole the Mollusca are a group of con-
siderable difficulty. The shells are much more external
structures than the coats of the Crustacea, have a less
intimate connection with the body, and are therefore not
of much use as guides to affinities, except to a very general
degree, while the study of the internal structure is not easy.
It is a natural result of this, that while much has been
written on the shells of Mollusca, their internal structure
is still in many cases insufficiently known.
Perhaps the easiest way to get a general notion of the
structure of Molluscs is to begin with the study of some of
the limpets. Knock off the rocks a f e w large specimens of
the common limpet, and look for the largest specimen you
can find of the little tortoise-shell limpet, or its relative
the little pink limpet, to be found far out on the rocks
Q 225
226
LIFE BY THE SEASHORE.
among the great blades of Laminaria. Put your specimens
in a glass jar filled with clean water, and examine the lower
surface (see Fig. 66). Some of the points of structure we
have already noticed : the muscular foot in the centre, used
here, as in many Molluscs, as a creeping surface ; the head,
separated from the foot by a constriction, and bearing mouth,
horns or tentacles, and eyes; the mantle-fringe, or flap,
hanging down at the sides of the body like a frill, and
secreting the conical shell above. In the tortoise-shell, but
not in the common limpet, there is a single plume, or gill,
exserted when the animal walks. These points studied,
drop your specimens for a few minutes into hot water or
spirit, and then remove the shells by slipping a sharp-pointed
knife round the sides of the animal. Detailed dissection is
not easy, but some points can be readily made out. Notice
that the mantle is arched in the
head region, so that it there forms
the roof of a small chamber —
the mantle-cavity, which in the
tortoise-shell limpet contains the
gill. The mantle-cavity is a very
important structure, and you
should take pains to assure your-
self that it is outside the body-
cavity, that it is equivalent to
the gill-chamber of the Crustacea,
and is formed by the downgrowth
of the mantle-flap, a free fold of
skin. One other structure is of
great importance; this is the
so-called tongue, or radula, a long,
brownish thread, much longer
than the animal, which lies folded up at the right side, and
is very easily found. When examined with the lens it will
be found to be covered with numerous rows of small teeth.
By means of it the limpets mow down the sea-grass upon
which they feed, but the carnivorous Molluscs use it as a
drill to perforate the shell of other Molluscs.
One other point must be noticed in regard to the anatomy
of the limpet. The posterior opening of the food canal,
instead of being at the end of the body, as one would
rr— g
FIG. 66.— Under surface of com-
mon limpet (Patella vulgatd).
mo, mouth; ma, mantle pro-
longed into fine processes ;
/, foot; g, respiratory region
of mantle.
MOLLUSCS, OB SHELL-FISH. 227
naturally expect, is close to the head at the right side —
that is, the limpet is unsymmetrical, the organs being, as
it were, twisted round to the right side.
The division of the Molluscs to which the limpets belong
is known as the Gasteropods. Gasteropods are usually
characterised by the presence of a shell, sometimes conical,
usually coiled, but at times absent. The mantle-fold is
single, and overarches a cavity which usually contains a
single gill ; but, as in Patella, this gill may be absent, when
its function is taken on by the mantle-fold. The foot forms
a flat surface used for creeping ; the head is distinct, bears
tentacles and eyes, and within the mouth there is almost
invariably a well -developed radula. The body is usually
markedly unsymmetrical, but where the shell is absent it may
exhibit an apparent symmetry. There are an extraordinary
number of Gasteropods, living on land, in fresh water, and
in the sea, the most familiar forms being those with coiled
shells, such as whelks, periwinkles, snails, and so on.
Contrasted in many respects with the Gasteropods are
the Bivalves, or Lamellibranchs, such as oysters, clams,
mussels, cockles, etc. One may think of them in relation
to Gasteropods in this way. Suppose in a limpet the body
were to be greatly compressed laterally, the simple conical
shell, one might suppose, would yield to the pressure so as
to divide into two valves united by a hinge; the foot would
lose its creeping surface and become narrow and compressed,
the mantle-flap would grow downwards at each side, and, in
conformity with the two-valved shell, would become double
instead of single. If we suppose that at the same time
the separate head, the tentacles, the eyes, and the radula
were to be lost, symmetry to be acquired, and a second gill
to appear, we should have roughly indicated the chief points
of difference between Gastercpod and Lamellibranch. The
latter are much more sedentary than the former, which
usually live buried in sand or mud, and show fewer varia-
tions in structure. All feed on microscopic food particles
in the water, and have large flat plate-like gills, whence
the name of Lamellibranch, and have a double shell, whence
the alternative name of Bivalve.
The third great set of Mollusca includes the active pre-
daceous cuttles, which are known as Cephalopoda. In
228 LIFE BY THE SEASHORE.
them the foot has grown up round the mouth, and is split
up into "arms" furnished with suckers. Except in the
pearly nautilus of the Pacific, there is no external shell,
and the structure is in many respects strangely modified.
Most of the cuttles live in the open sea, and they are not
common on the shore rocks.
In studying the Mollusca we shall first consider the
Gasteropods, beginning with some old-fashioned forms, which
are sometimes separated from the Gasteropods, because they
are in many respects of simpler structure. These are the
species of Chiton, animals very common on our coasts, and
known as fossils from very early rocks. So
abundant are the Chitons on the shore rocks,
that one species at least can always be found
.even at the most sluggish of neap tides. They
live on and under stones, and are of small
size, being usually not more than about half
an inch in length, and often less. The shape
FIG. er.-CMto» (see FiS' 67) is a long oval> and the most
marginatus, marked characteristic in surface view is the
showing's presence of no less than eight overlapping
eight shells, shell-plates, embedded in a tough roughened
mantle, which projects at the margin of the
plates. Remove the animals from the rocks with your
ringers, and you will find that they immediately begin to
curl up, bending the body at the junctions of the plates.
Watch living specimens crawl over the muddy shale, and
notice the slug-like movement, and the muddy track left on
the rock. Induce your specimens to crawl up the side of a
clear glass vessel, and study the under surface. In the
centre lies the foot, a muscular creeping surface, as in
limpet or snail. In front of it, and not clearly separated
from it, is the head, without tentacles or eyes, but with a
very distinct mouth-opening. By watching closely you may
see a brown ribbon protruded from this opening, and used
to scrape off the glass the small green Algse which soon
grow in aquaria ; thus Chiton has a radula in its mouth just
as the limpet has. At the sides of the foot are the gills,
arranged in longitudinal series, and usually about sixteen in
number. The posterior opening of the food canal is at the
extreme end of the body, as far as possible from the mouth.
MOLLUSCS, OR SHELL-PISH. 229
We cannot here go into the minute details of the struc-
ture of Chiton, but may briefly call attention to its more
salient features. It is a true Mollusc; it has a mantle
which secretes the dorsal shells, a ventral foot, it breathes
by gills. It resembles the Gasteropods in the condition of
the foot, and in possessing a radula or tooth-ribbon within
the mouth. But it differs in many respects from the
Gasteropods. Instead of having one shell it has eight;
in place of the single gill of most Gasteropods it has eight
pairs ; instead of being unsymmetrical, with the organs
apparently twisted to the right, it is perfectly symmetrical
with mouth at one end and anus at the other, like worm
or Arthropod. In brief, it is a simple and primitive form.
It should be especially noticed that it resembles worms and
Arthropods in showing traces of segmentation. We have
already noticed that in both these groups the body is made
up of a repetition of similar parts — is distinctly segmented.
Now in the Mollusca such segmentation is typically absent,
its absence being one great point of contrast with the
Arthropods. The number of shells in Chiton, and their
relation to the gills, point, however, to the existence of
segmentation in this primitive form. This is a point of
much interest to those who care about problems of origin.
The species of Chiton are chiefly distinguished by the
minute characters of the shells. The commonest form is
Chiton marginatus, and is very variable in colour and size,
but is distinguished by the finely granular surface of the
valves. Each valve has a slight central keel prolonged
posteriorly into a small beak, and is divided into three
areas by two diverging lines. All the areas are similarly
marked with fine dots, sometimes partially rubbed off in
old specimens. The colour is usually greenish, marked
and dotted with pale colour, but bright red varieties also
occur.
Another common and much prettier species is 0. fascicu-
laris, characterised by its comparatively small valves, and by
groups of bristles placed on the margin of the mantle.
There are eighteen of these groups, four being placed in
front of the first valve and a pair in front of each succeed-
ing valve. The individual valves should be examined with
a good lens, when their brilliant colouring and beautiful
230 LIFE BY THE SEASHOKE.
markings are clearly seen. Each has a central ridge orna-
mented by coarse longitudinal lines and ending in a beak,
and two lateral areas ornamented by curious " tear-shaped "
granules, whose pointed ends are directed towards the
beak. The sculpture as a whole is interesting and very
characteristic.
Another species, C. ruler, easily recognised but not very
common, is of a bright, shining red colour, marked and
variegated with white. The surface of the valves is per-
fectly smooth and without trace of sculpture.
By far the commonest species is C. marginatus, which is
abundant everywhere on shore rocks. It is almost confined
to the littoral zone, and is very variable.
After the Chitons we come to the Gasteropods proper, in
which the shell, when present, is always simple and often
coiled. The classification is a matter of some difficulty, for
those now in use depend upon anatomical details which are
somewhat beyond our scope. We shall consider the true
Gasteropods as divided into three orders: (1) the Zygo-
branchia, (2) the Azygobranchia, (3) the Opisthobranchia.
The first order includes the limpets, of which there are
many kinds. Sometimes two gills are present, sometimes
only one, as in Acmc&a, while in yet other cases, as in
Patella, there is no gill at all. The name, which signifies
" gills paired," is therefore a little deceptive. The shell is
usually cap-shaped, and never more than very slightly
coiled. In the general case there is little difficulty in
recognising the common limpets.
The Azygobranchia ("gills unpaired") include the great
majority of the snail-like Gasteropods of the shore. The
shell is usually large and coiled, and there is a single gill.
The third order, the Opisthobranchia ("gills posterior"),
includes forms which are often not easy to recognise as
Molluscs at all. The shell is often absent, and is never well
developed. When a gill is present it is placed behind the
heart, instead of in front of it as in other Gasteropods ; but
usually there is no true gill, its place being taken by out-
growths of the mantle. Often brilliant in colour and quaint
or beautiful in form, there is at least no fear of confusing
the Opisthobranchs with other Gasteropods. They are
very abundant on the shore, especially at certain seasons
MOLLUSCS, OR SHELL-FISH. 231
of the year; the commoner forms are called sea- slugs or sea-
lemons.
For clearness let us briefly summarise this classification of
Gasteropods, or Molluscs in which the foot forms a ventral
creeping sole.
GASTEROPODA.
1. Zygobranchia, limpet-like forms, generally with
simple, more or less conical shell.
2. Azygobranchia, forms like whelk and periwinkle
with coiled shells.
3. Opisthobranchia, forms in which the shell is often
absent and never well developed.
The Chitonidae with eight shells and eight pairs of gills
are often separated from the true Gasteropods.
We shall take first the limpets as representatives of the
Zygobranchia. On the East Coast, at least four of these are
common between tide-marks. Commonest of all is Patella
vulgata, the limpet of the fishermen, which is too familiar to
need description. It is always abundant between tide-marks
on rocky coasts, and is often found in little pits or depres-
sions of the rock, into which the shell exactly fits. It has
been shown by experiment with marked limpets that each
limpet has its own particular habitation, to which it retreats
as the water begins to ebb. When the rock on which the
limpet has settled down is covered again with water, how-
ever, the limpet sets out in search of the Algse which form
its food. As it travels it forms a broad track, often very
distinct where it has crossed sand or muddy rock. Experi-
ments on the " homing instinct " of limpets are easily made,
and can be carried out at neap tides on days when other
shore work is largely stopped. The common limpet is in
great demand for bait on most parts of the coast. It seems
popular with most fishes, a somewhat curious fact since it is
so purely littoral in habit. It is in many ways an interest-
ing species, and the student should not fail to watch the
way in which the peculiar tongue is used to mow down the
small Algae on which it feeds. As it glides over the rocks
the long tentacles are moved about in all directions, and
show clearly the small eyes at their bases. The position of
the eyes should be contrasted with that seen in the garden
232 LIFE BY THE SEASHORE.
snail (Helix), where the eyes are borne at the end of the
long tentacles. Most common marine Gasteropods have eyes
placed in the position seen in Patella.
The next limpet we shall consider is a much prettier form
than Patella, and in its own area almost as common. To
find it we must choose a spring tide, and tramp steadily
outwards till we top the last reef, and come down to the
sea-meadows where the giant Laminarice flourish. Choose
a spot where you can look down on the floating fronds, and
you will see that they are spotted with tiny shells of the
same tint as the weed, but barred with radiating lines of
shimmering blue. The colour is of the kind known as
optical, and as the long fronds sway gently in the water,
its living jewels glow blue or green according as the light
touches them at one angle or another. When first seen
under favourable conditions this is one of the sights which
stay in the memory, for there is something in the exact
harmony of colour between weed and shell which seems to
give the blue colour an added glow. Beautiful as the
limpets are, however, they are not quite harmless com-
panions for the oar-weed, for you will find that they eat
very considerable holes in its fronds, in spite of their small
size as compared with them. Pull up a plant of Laminaria
by the roots, and embedded in these, in company often with
many other strange creatures, you will find another variety
of the limpet. While the first variety is a thin, delicate,
transparent shell, brown in colour with blue rays, the second
is much stouter, paler in colour, and usually without trace of
the blue rays. The first is the typical Helcion. pellucidum,
the second Helcion pellucidum var. Iccvis. The first eats
the fronds of the oar-weed, and so produces those torn and
ragged fragments which are constantly thrown on the beach ;
the second, by burrowing in the roots must weaken these,
and so assist the waves in tearing up the great plants which
appear on the shore after every storm. They usually bring
with them many curious and beautiful creatures, so the
naturalist has some reason to be grateful to the tiny limpet.
The transparent limpet is closely related to Patella, and
in the absence of a true gill differs from the next two
limpets, Acmcea testudinalis and Acmcea virginea, which
both possess a delicate white branchial plume. In habitat
MOLLUSCS, OB SHELL-FISH. 233
they offer the same contrast as Patella and Helcion, for
while the tortoise-shell limpet is to be found not far below
high-tide mark, Acmcea virginea is only to be found among
the LaminarioB. We have, however, already (p. 24) seen
that Acmcea testudinalis differs from the common limpet in
being confined to the pools, and in never
climbing high above the water level, as
Patella vulgata does. It is a pretty little
creature, easily recognised by the distinct
pattern in brown on the shell, and the very
dark brown " spatula " or mark in the inside
of the shell. The mantle is bright green FIG. 68.— Tortoise-
and the eggs bright red, so the animal does (AcmLa llestudt
not lack bright pigments. The allied form, naiis).
A. virginea, is of similar size and appearance,
but has the shell ornamented with rays of pink instead of
the brown network of the other species. The spatula is
not brown, and the mantle has not the vivid green colour
of the tortoise-shell limpet. It will be found attached to
shells and stones in the Laminarian zone. On the South
and West Coasts other limpets will be found in addition to
these four.
After the limpets we come to the Azygobranchs — peri-
winkles, whelks, dog-whelks, and similar forms, with strong
spiral shells and active habits. To make sure of them
collect on the shore a handful of common forms, such as
the large whelks, very common in some places under muddy
stones, a few periwinkles, some living tops ("silver Tommies"),
or any other spirally coiled shells which catch your eye, and
drop them into a basin of clean water. Note the different
shapes of the shells, largely dependent upon the number
and shape of the coils, and also the fact that while some of
the shells have smooth rounded mouths, others, such as the
whelks, have the mouth prolonged into a canal. Note, too,
the general characters of a coiled shell; all have a centra]
pillar or columella, a large body-whorl, a spire made of other
smaller whorls, a mouth with outer and inner lip, and so on.
Another point will be very obvious, namely, that not only
can the animal retreat into its shell in a way which is
impossible for a limpet, but that when it does retreat it
" shuts the door " behind it, by means of a firm plate, or
234 LIFE BY THE SEASHORE.
operculum (o in Fig. 70), so placed as to block the mouth of
the shell when once the animal has withdrawn into it. If
the chief function of the shell be for protection, then the
shell of the Azygobranchs is more efficient than the shell of
the Zygobranchs.
While you have been making these observations, some of
your specimens will have recovered from their alarm, and
have begun to crawl about the basin. In such expanded
specimens notice as before the creeping foot (/ in Fig. 70),
not unlike that of the snail, and also the relation of the
operculum to it. A comparison of forms with notched and
unnotched shell will show further that in the former a long
tube or siphon (see Fig. 70, s) can be protruded along the
canal or notch. This siphon is a specialised portion of the
mantle, and conveys water to the mantle-chamber in which
lies the gill. You will remember that in the tortoise-shell
limpet the gill itself is protruded as the animal walks ; but
gills are delicate, easily injured structures, full of blood,
and not to be exposed without some risk, therefore we
find that with the specialisation which gives the Azygo-
branchs their more complex shells, there is usually more
efficient protection for the gill, which is now usually hidden
permanently within the mantle-chamber. Lest, however,
in this position the gill should not be sufficiently exposed to
the purifying action of the water, there is in many cases a
long siphon which conveys a current of water to the mantle-
chamber. We have already noticed a similar condition of
affairs in the Crustacea, where in the higher forms the
position of the gills in a gill -chamber necessitates very
elaborate arrangements for renewing the water. Curiously
enough it is found that almost all the siphonate Azygo-
branchs are carnivorous, while those without siphons are
vegetarian. The former are more specialised than the latter.
Notice, also, that the Azygobranchs have a much better
developed head region than the limpet. It is often prolonged
into a proboscis, which may, as in the whelk, be capable of
being protruded and retracted. The tentacles are often very
long, and in some cases, as in the tops, there are numerous
tactile processes in addition to the tentacles proper.
While the limpets lay their eggs singly in the water, the
Azygobranchs lay them in clusters or capsules which arc
MOLLUSCS, OK SHELL-FISH. 235
often curious and interesting in appearance, and in several
cases are among the commonest of the objects found on the
seashore.
Among the Azygobranchs we shall begin with the familiar
"silver Tommies" of our youth, the "tops" of south-
country children, and the Trochi of scientists. All children
recognise at least two varieties, the common "silver
Tommies," valuable only in very early youth, and the large
pink ones, which, with the finer scallops, constitute the
gems of all early collections. The common form is Trochus
cinerarius, and can always be found in the living condition
on the rocks; the large is T. zizypliinus, and is an inhabitant
of deeper water, sometimes tossed on shore after storms.
There are, however, especially in the South, very many other
species, some of which live in deep water, and others on
the tidal rocks. Choose the species which is most abundant
in the locality at your disposal — it will probably be Trochus
cinerarius — and study it in the
living condition. Notice the small
conical shell, with its rounded, un-
notched aperture — the animal has
no siphon, and is vegetarian. As it
protrudes itself from the shell, notice
the operculum borne on the foot, the
foot itself, narrow in proportion to
its length, the large head prolonged
into a non-retractile snout, and bear-
ing two long tentacles, and two eyes
placed on short stalks, which spring
from the base of the tentacles. Between the tentacles are
two distinct " head-lobes," while to their outer sides lie two
greatly developed " side-lobes," with long, delicate processes,
or cirri (see Fig. 69). The cirri move about as the animal
progresses, and add considerably to its appearance. The
operculum is peculiar in being spirally coiled, as it is in all
the Trochi.
As to the special characters of the shells of the different
species, in T. cinerarius the whorls are somewhat flat, and
six in number, the base of the shell shows a narrow hole
called .the umbilicus, the shell is marked by coarse, spiral
lines, and is of a dull ash colour, marked by oblique lines
236 LIFE BY THE SEASHORE.
of darker tint, which run in the opposite direction to the
lines of growth. Shells found on the beach often have the
outer coat rubbed off, and are then "silvery," that is, they
show the mother-of-pearl lining.
The large Trochus zizyphinus (see Fig. 69) is on the
east an inhabitant of deep water; on the west it occurs
between tide-marks, and the shell is common on most
shores. The shell is conical in shape, and may reach a
height of over an inch, the base is without a perforation,
there are eight or ten whorls, and the shell is usually
spotted with bright rose colour. In the general case the
species is readily recognised.
There are very many other species of Trochus found in
Britain, some in deep water, and some found in the tidal
pools in the South and West.
The next set of forms we shall consider are the peri-
winkles, an interesting and puzzling group. As the name
of the genus — Littorina — indicates, they are purely littoral
forms, living almost exclusively between tide-marks, and
showing much tolerance of fresh water and of dryness. On
the one hand they are related to the genus Lacuna, whose
members inhabit the Laminarian zone and deeper water,
and on the other they are connected with Paludina, a genus
of fresh -water forms, and they occupy every variety of
habitat between those of these genera. High up on the
cliffs, out of reach of all but the spray, on the stones of
the streams which run down the beach, on the tidal rocks,
on the broad blades of Laminaria, there are few localities
on the shore in which the ubiquitous periwinkles do not
occur. It is true that in most cases the different localities
are characterised by one dominant form, but in not a few
cases the species themselves have a wide range, and I have
picked four so-called species off one stone. You probably
do not need to be told that this is very exceptional, and for
a very obvious reason. It is an axiom of the modern theory
of evolution that those divergences of structure which ulti-
mately result in the formation of new species have been
produced by divergences in the environment. Take as an
example the two species of porcelain -crab already con-
sidered (p. 179). The minute porcelain -crab is adapted to
one environment, the hairy porcelain -crab to another, and
MOLLUSCS, OB SHELL-PISH. 237
their differences are directly associated with the differences
in their surroundings. The latter, by virtue of its hairy
coat, can live among mud, which the former cannot. It,
on the other hand, from its superior agility, can probably
escape enemies which the other could not, and is therefore
enabled to live in more exposed places. If hybrids between
the two were to occur they would probably be well adapted
for the habitat of neither, and so would tend to be elimi-
nated. In other words, marked and permanent differences
of environment tend to produce marked and permanent
differences in species.
If we return to the periwinkles we find that there is no
such marked difference in the environment in this case.
They are tolerably active animals, and therefore, though
each species may theoretically have its own zone, its mem-
bers seem to wander freely into the zones of other species.
This must have two consequences. In the first place,
divergence will be probably checked by constant inter-
breeding; secondly, if the adults wander freely, their
adaptation to any particular locality cannot be very exact,
and there is no reason to believe that hybrids will be more
likely to be eliminated than pure forms. That is, the
species should not be well defined. Now this is what
actually occurs; there are a great number of periwinkles,
and in many cases it is almost impossible to distinguish
between species and varieties. There can, I think, be no
doubt that this is due to the continuity of the environment.
It naturally, however, makes the identification of species
very difficult, and the distinction of species a fruitful source
of controversy. A modern will no doubt say their distinc-
tion is a matter of no importance; but if the attempt
makes clear the meaning of variation, it is not without its
usefulness.
Let us first answer the question, What is a periwinkle?
All the periwinkles have solid top-shaped shells, with a
short spire and an entire mouth. The surface of the shell
is sometimes smooth, sometimes spirally grooved. The
mouth is nearly circular, and has a sharp-edged outer lip,
while the other or columellar lip is expanded. The oper-
culum is pear-shaped, horny, spirally coiled, with its centre,
or nucleus, laterally placed. In the living animal the head
238 LIFE BY THE SEASHORE.
is seen to bear two tentacles, which have two almost sessile
eyes at their bases. There are no lobes nor cirri such as
occur in Trochus. The foot is rounded at both ends, and
has a very distinct central groove. Make out these points
on a living common periwinkle, and then make a special
journey to the rocks to collect the different forms in the
living condition. Begin at high-tide mark and collect speci-
mens down to low-tide mark. Then, either indoors or at
the rocks, sort your specimens carefully. Pick out first the
common periwinkle (Littorina littorea), which is known by
sight to most people, and is almost always easy to recognise.
The shell is usually black, sometimes brown or red ; in the
young the surface is ridged, but the adult shell is often
nearly smooth. Having put aside all the specimens which
are obviously the edible kind, take out from the remainder
those with distinctly flattened spire, in which the coiled
part of the shell seems to be sunk into the last whorl.
This is L. obtusata. The shell has a peculiarly smooth
surface, and is very variable in colour, being usually shades
of yellow and brown. It lives chiefly among bladder wrack
(Fucus). Among the remaining specimens you will find a
number of yellowish colour, often banded, which, except
for their colour, present much general resemblance to the
common periwinkle. From it they differ especially in the
greater roundness of the whorls, and in the breadth of the
outer lip of the mouth, at the point where it joins the
columella, or pillar, which forms the central axis of the shell.
The result of this broadening of the outer lip is to give the
aperture the appearance of being partially filled up. This
form is L. rttdis, a species which lives near high-tide mark,
and is very variable, giving rise to several more or less
distinct varieties. The most distinct of these is the form
called L. patula, which has an ear-shaped shell with a
somewhat oblique spire. There are other species or varieties,
such as L. neritoides, a small form living above high-water
mark; but if those mentioned above are distinguished the
observer will do well.
The special characters of the forms named may be briefly
described. The common periwinkle, Littorina littorea, is
denned by the combination of the following special charac-
ters : the surface of the shell, especially in the young stage,
MOLLUSCS, OB SHELL-FISH. 239
is marked by striae, the whorls are more or less flattened,
the outer lip of the aperture joins the last whorl at an
acute angle, and is more arched below than above. On the
last point special stress should be laid, as it is very character-
istic. The colour of the shell has been already described';
as to the colour of the living creature, the fact that the
horns and tentacles are spotted and ringed with black is
especially noteworthy.
It is much easier to distinguish between actual specimens
of L. littorea and the next species, L. rudis, than it is to say
wherein the difference actually consists. In the latter the
whorls are distinctly rounded, the outer lip joins the last
whorl at a right angle, and is more arched above than
below. This, which is an important difference from the
common periwinkle, may seem a very trivial matter, but it
has, in reality, considerable bearing on the life-history. The
common or edible periwinkle lays eggs on Fucus in little
jelly-like patches, a habit which is no doubt the primitive
one for the species. But such a habit is obviously im-
possible for forms like L. rudis and its varieties, for they
inhabit localities often not covered by every tide, and un-
suited to the growth of the tangles. It therefore retains its
eggs within the body until the .young develop, and they are
subsequently born already furnished with shells. There
can be little doubt, I think, that the shape of the shell-
mouth bears a direct relation to this viviparous habit — it
allows room for the young to develop, and makes birth easy.
Practically, the viviparous habit is of some importance,
because it renders this species unfit for food, owing to the
grittiness imparted by the presence of the young during
several months of the year. The species never reaches the
size of the preceding.
The form called L. patula is merely a variety of L. rudis,
but lives even further up on the shore. It is usually smaller,
has a thinner shell and a more stunted appearance, the
whorls, especially the last, are more expanded, and the
aperture of the shell is wide. As in L. rudis, the tentacles
of the living animal are usually marked with longitudinal
stripes, not with rings or spots, as in L. littorea.
Typical examples of L. obtusata are so easy to recognise
that it seems unnecessary to describe their characters
240 LIFE BY THE SEASHOEE.
further than to re-emphasise the peculiar flatness of the
spire.
The four types given here have been chosen because I
have found them to be the most abundant on the shores of
the Firth of Forth, but the periwinkles of any area form a
most interesting study.
Related to the periwinkles are two genera of minute
shells, which we can only mention without description.
The first of these is the genus Rissoa, which includes a
great number of British species, inhabiting very various
depths of water. To obtain examples pluck a good handful
of any of the finer seaweeds, and drop into a dish of sea-
water. Presently there will crowd to the surface numerous
minute forms with spirally coiled shells often beautifully
sculptured. They are active little creatures, crawling over
the seaweed, or taking advantage of surface tension to creep
along the surface of the water, shell downwards. The
other genus is Skenea, including especially Skenea planorbis,
a common shore form with a circular depressed shell. It is
very minute, being just visible to the naked eye.
On many parts of the coast " tower-shells " (Turritella)
are found very commonly thrown on the beach. There is
only one British species (T. communis), and it is an
inhabitant of deep water, so that the living animal is not
likely to be found. The shell is elongated and tapering, it
has sometimes as many as nineteen whorls, of which the
first ten bear three distinct ridges. The aperture is entire
and rounded. The shell is usually of a brownish colour,
and may be over two inches in length.
Though Molluscs which only occur in the dead state are,
strictly speaking, somewhat outside our scope, we must
mention the curious " pelican's foot," Aporrhais pes-pelecani,
which is not infrequent on the shore. The shell is turreted,
very strong, with numerous ornamented and ribbed whorls.
The mouth of the shell is furnished with a short canal,
and in the adult its outer edge is expanded into a large
lobed plate. The shell is interesting on several accounts,
especially because it is in some respects transitional between
the Azygobranchs, with round entire aperture like Trochus,
and those with canaliculate, or notched aperture like
Bvacinum. The living animal is beautifully flecked with
MOLLUSCS, OE SHELL-FISH. 241
scarlet, and may occasionally be found flung ashore after
storms.
Before passing to the siphonate Azygobranchs, we must
mention one other form not uncommon in some places
between tide-marks which is very different in appearance
from its allies. This is Lamellaria perspicua, especially
interesting because the shell is very thin, and is completely
covered by the mantle. This reduction of the shell occurs
in many different sets of Gasteropods, but is rare in the
littoral Azygobranchs. In Lamellaria the body is very
convex, without external trace of shell, is usually yellowish,
but may be white or purplish. The head bears two tentacles,
with small eyes at their bases. The animal is very active,
and may reach a length of two inches, but between tide-
marks specimens are usually of very much smaller size. It
is possible, by very slight dissection, to find the concealed
shell which lies in the middle of the back, .and is of a
delicate white colour, with a mere trace of a spire. The
living animal is apt to puzzle the beginner very much, for it
has few characters which can be very definitely laid hold of,
and specimens between tide-marks are not infrequently of
very small size. On the dorsal surface notice the rounded
mantle, often highly spotted and marked, and with a very
characteristic notch anteriorly over the head, which serves
as a kind of siphon to admit water to the small chamber in
which the gill lies. When the animal crawls it trails a
translucent foot behind it, while the long, slender tentacles
project in front. If it be turned over, the broad, creeping
surface of the foot will become very obvious, and also the
large, black eyes at the base of the tentacles. The animals
are to be found under stones between tide-marks, and on
account of the activity of their movements are very charm-
ing occupants of an aquarium.
Of the carnivorous siphonate Azygobranchs, the common
Purpura lapillus is perhaps the most abundant 011 the shore.
Like many of its allies it yields a purple dye similar to
that which furnished the ancients with their famous Tyrian
purple. In some places it is called the dog-periwinkle, and
is one of the most variable of shore animals, and one of
the most abundant. It is purely an inhabitant of the
littoral zone, and lives upon other Molluscs, chiefly Bivalves,
B
242 LIFE BY THE SEASHORE.
which it attacks by first drilling a round hole in the shell,
and then sucking up the soft contents by means of its pro-
trusible proboscis. At low tide the dog-periwinkles remain
motionless attached to the dry rocks, but they have a curious
habit of suddenly relaxing their hold and dropping into
the pools beneath. Beneath overhanging rocks their egg
capsules may be found at all seasons, sometimes empty
and sometimes full, and not infrequently stained with the
creature's purple dye.
The shell is very strong, usually white or pale yellow,
with a very large body-whorl and a distinct but short canal,
and in the adult reaches a length of over an inch. The
surface is usually nearly smooth, but in one variety the
lines of increase rise up to form "fringe-like imbricating
lamellae," and there are in addition spiral ridges placed very
close together. The colour is very variable, the shell being
sometimes banded with dark brown and sometimes entirely
dark brown ; the shape is also variable.
The living animal is pale in colour, usually white. Behind
the head lies the gland which secretes the colourless fluid
from which the purple dye is obtained by exposure to the
air. The egg capsules are little oblong, shortly-stalked cups,
and are placed in clusters on stones and shells.
The next two species belong to the genus Nassa, and are
usually more abundant as shells on the shore than in the
living condition. The shells are prettily marked, and in
the young state are often collected by children in quantities
to make necklaces or ornaments. Both species are some-
times found living near low-tide mark.
The larger species, Nassa reticulata, has a thick shell of
pale brown colour, which may reach a length of one and
a half inches. It is covered by numerous convex ribs,
which are crossed by spiral grooves, producing a netted
appearance. The aperture is prolonged into a short and
broad canal. The animal is yellow, speckled with black,
and has the foot prolonged into two filaments, usually
carried upright when the creature walks.
The other species, N. incrassata, is much smaller, has the
whorls of the shell rounded, and a dark spot placed at the
origin of the canal. The aperture is largely filled up by a
projection, or varix.
MOLLUSCS, OB SHELL-FISH. 243
The next form is a very interesting one — it is the common
whelk, or "buckie" of Scotch children. Between tide-
marks it is usually small, but in deeper water grows to a
length of six inches, and in many places is much valued
both as food and bait. It is very widely distributed and
common, and, like so many other common shore Gastero-
pods, is very variable, tending especially to run into local
varieties. It is extraordinarily abundant between tide-marks
in the Firth of Forth, where it lives chiefly in mud and
sand, and is often beautifully coloured. The egg capsules
are very common objects in autumn and spring, both on the
shore rocks and cast up among the refuse on the sand.
They are interesting objects and well worth study.
Each capsule has a tough wrinkled coat and is of irregular
shape, and the capsules are aggregated together in masses
varying in size from a small cluster like half a lemon to a
mass as large as a child's head. The spawning season is in
autumn, though, as in many Molluscs, it seems to be of long
duration. Each capsule when laid contains 500-600 eggs
inclosed within a space of a quarter of an inch to half an
inch in diameter, so that some estimate may be formed of
the enormous number of eggs produced by the parent.
Relatively very few of these eggs, however, develop. For
some reason not yet adequately explained, some five or six
in each capsule get the start, and begin to develop rapidly.
As they do so they devour their less successful brethren,
and on opening the capsules one finds the infant monsters
with their transparent bodies distended by some seventy to
eighty undeveloped eggs. By the help of this food they are
enabled to remain within the egg-case until the shell is fully
formed, when, in spring, they finally leave it, and begin life
on their own account. This sacrifice of many eggs to the
few which develop is common among shore Gasteropods, but
it can be observed perhaps most readily in the common
whelk.
Whelks are probably more or less familiar to most people,
so it is not necessary to describe them in very great detail
(see Fig. 70). The living animal is both interesting and
beautiful, and an attempt should be made to keep a few
specimens in confinement. To do this with success it is
necessary that they should be supplied with a considerable
244
LIFE BY THE SEASHORE.
bulk of water. In such living specimens notice the strong
operculum (o) with which the shell can be entirely closed,
the large creeping foot (/) beautifully mottled and speckled
with black, the long
siphon (s) which is
protruded along the
canal of the shell
and waves freely in
the air as the animal
walks, the broad
head (h) with the
pointed flattened
tentacles bearing
the distinct eyes,
and the long pro-
Fio. 70. — Common whelk (Buccinum undatum), show- boscis which can
ing the animal as it appears when crawling. For *, nrotrndpd from
explanation of letters see text. 3 protru
the mouth. The
shell varies considerably in colour, but is usually more or
less brownish; it is spirally grooved and striated, and
usually marked with oblique transverse undulations which
do not traverse the whole of the body-whorl. It is very
thick and strong, especially in forms from deep water. It
is not usual to find the whelk abundant between tide-
marks except in the North, but, as already noticed, it is
very common on the coasts of the Forth.
Allied to Buccinum is the genus Fusus, whose members
are called spindle-shells, or red whelks, or buckies. The
two commonest species in the North are F. antiquus and
F. islandicvs. Both are inhabitants of deep water, but are
sometimes thrown up in the living state by storms. The
shells are common on the shore at all seasons, and are not
infrequently found in rock pools occupied by hermit-crabs.
A full-grown hermit requires for his accommodation an
adult shell of Buccinum or Fusus antiquus, and when the
latter is chosen the result is singularly beautiful. The shell
is usually pure white, the colour deepening into yellow
within the large aperture. It may reach a length of over
six inches and is always peculiarly graceful in shape. The
shell of Buccinum, on the other hand, is only beautiful
when small, the large specimens tending to become thick
MOLLUSCS, OR SHELL-FISH. 245
and clumsy. The other species of Fusus, F. islandicus, is
much smaller and more distinctly spindle-shaped; the two
species may be recognised and distinguished by the following
characters. In the larger species the surface of the shell is
covered by numerous strong striae placed very close together.
The mouth is very large, being longer than the spire, and
about twice as long as it is broad. The result is to produce
a shell which is very wide at its lower part and only tapers
very gradually above. In Fusus islandicus the surface is
covered by relatively few strise, separated from each other
by an interval broader than they are themselves. The
mouth is not so long as the spire, and the breadth is only
about a third of the length. In consequence the body-
whorl is narrow, and tapers suddenly to a somewhat sharp
point.
The only other of these Gasteropods we shall mention is
that curious little one known as the " blackamoor's tooth,"
or cowry, which is so common on the beach, and is so often
collected in hundreds by enthusiasts who spend the greater
part of their summer holiday poring over the beds of
gravel in which the little shells are found. I have often
wondered whether the results in the shape of long necklaces
of perforated shells are worth the labour and the backaches
of the gathering. The living animals, however, are exceed-
ingly interesting, and may sometimes be found on the rocks
near low-tide mark. When fully expanded two bright
orange folds envelop the shell so as to almost conceal it.
The tentacles are very long, and, like the rest of the head,
the foot and the siphon, are of a pale yellow colour. When
very young the shell is coiled as in most Azygobranchs, but
as it grows the spire is concealed by the growth of the
body-whorl, and the inflection of the lip produces the long
narrow aperture so characteristic of the cowries, to which
family the present form — the Cyprea europcea of systematists
— belongs. The living animal is a most gorgeous little
creature, the prevalent orange tint being often set off by
bands and markings of other colours, or replaced by a
pinkish colour. The shell is quite white, as is often the
case with concealed shells.
246
LIFE BY THE SEASHORE.
KEY FOR IDENTIFICATION OF MOLLUSCA DESCRIBED
IN THIS CHAPTER.
CHITONID.E, one genus, Chiton
Surface of shells finely granular
Surface quite smooth. Colour red
Mantle with tufts of bristles .
8 shells, 8 pairs of gills.
C. margiiiatus.
G. ruber.
C. fascicularis.
vulgatat
(1) GASTEROPODA ZYGOBRANCHIA (shells cap-shaped).
{Shell with strong \ pate77a
ridges . . . /
Shaend Sate8?100*1! } ^kion pellucidum.
' Shell with tortoise- ^
shell pattern in V Acmcea testudinalis.
brown
One gill present
(2) GASTEROPODA AZYGOBRANCHIA (shells spirally coiled).
(a) Forms without a siphon.
' T. cinerarius,
shell with
hole at
Shells more or
less top-shaped
Base flat, shell \
pearly inside, f
whorls nu- I Trochus
merous. Ani- I
mal with cirri. J
Shell thick, not ^
pearly,whorls r Littorina
few. No cirri. '
Whorls
base,
six whorls.
T. zizyphinus,
no hole, eight
to ten whorls.
L. littorea, shell
red or black,
surface ridged.
L. oblusata, sur-
face smooth,
spire flattened.
L. rudis, whorls
round, lip
thickened.
Shells very long, J Whorls with \
with many-! tubercles,
whorls .
VU*/w4vJlvOj I
outer lip ex- r Aporrhais pes-pclecani.
panded into I
Shell very thin, -v
concealed, I
mantle with j
anterior notchl
plate
Lamellaria perspicua.
MOLLUSCS, OR SHELL-FISH.
247
(6) Siphonate forms.
Spire sharp- \
pointed, canal r
narrow . . '
Spire short, \
Shell oval, spir- canal short j
ally sculp- I and recurved, I
tured, canal \ columellaj
short . . with fold at I
base . . J
Spire blunt, -\
canal open j-
and deep . J
Shell spindle- ] f
shaped, with I „ „
long straight ( FuSUS ' ']
canal . / I
Shell with con- \
rp±reSP4 ^~^"
Purpura lapillus, shell white or
banded.
N. reticulata,
shell large.
N. incrassata,
shell small,
aperture much
narrowed.
Nassa
Buccinum undatum
dulated.
shell un-
F. antiquus, strise numerous, body-
whorl wide.
F. islandicus, strise few, body-
whorl narrow.
For (3) GASTERoroDA OPISTHOBRANCHIA, see next chapter.
NOTE ON DISTRIBUTION.
From the great multitude of shell-bearing Gasteropods we have
been able to pick out relatively so few that not much can be profit-
ably said as regards the distribution generally. Most of the forms
mentioned occur all round the coast. The whelks lusus islandicus
and Buccinum undatum may be mentioned as forms commoner in
the North than in the South, while the cowry (Cyprea) is an example
of one commoner on the South and West, at least between tide-
marks, than on the East Coast. We have already indicated that
although the pretty tortoise-shell limpet is absent from the South
and West, its absence is atoned for by many other curious and
interesting forms. A similar replacement of species occurs among
other genera. Thus at Lynmouth, on the north coast of Devon, the
common grey top ( T. cinerarius) appeared to be absent, but the pools
were filled with two other species — a small one prettily marked with
brown (T. umbilicatus), and a larger dark-coloured one (T. lineatus).
But, allowing for such cases, it may be said generally that the
Gasteropods which are hardy enough to live between tide-marks are
also hardy enough to live all around our coasts.
CHAPTEE XIII.
THE SEA-SLUGS.
General characters of Opisthobranchs — The sea-hare — The sea-lemons,
or Dorids — Five common species — The spawn and breeding habits
— Development — Goniodoris, its structure and habits — Some other
sea-slugs — General characters of the colouring — Their inedibility
and its causes — The Eolids — Three common species — General notes
WE now come to a singularly interesting and beautiful
group of Gasteropods, mostly without shells, and often
of very singular shape. They constitute the group of the
Opisthobranchs, and, as already seen, are characterised by
the fact that the heart is in front of the gill when this
is present, instead of being behind it, as in the Gasteropods
just considered. The greater number of these shell-less Gas-
teropods are often called sea-slugs, or Nudibranchs ("gills
exposed"), and certain sea-slugs are abundant on every
shore. Most of them, especially the smaller kinds, live
well in confinement, and should be studied in the living
condition. They do not preserve well, both colour and
shape being usually lost even under favourable conditions,
and they are rarely to be found in museums ; so that unless
you draw and describe your specimens as you find them,
there is little chance that you will be able to name them
afterwards. Again, many of them seem to be more or less
migratory in their habits, and are not found between tide-
marks except at the breeding season. As this usually falls
in the colder months, you can hardly hope to find such
species if your visits to the shore are confined to the
summer. In March, for example, I have seen the shore
rocks whitened by the spawn of forms which in summer
are rare, but at this time occurred in clusters of five or six
248
THE SEA-SLUGS. 249
at every patch of spawn. One other point, — the rocks at
your disposal may abound with some of the smaller and
more delicate forms, and yet you may be unable to find
a single specimen. It must be remembered that out of
water many of the sea-slugs collapse into a shapeless mass,
while in the water they may so closely resemble the coral-
lines or zoophytes among which they live as only to be
distinguished with great difficulty. I do not know any
more laborious task in shore hunting than crouching beside
densely fringed pools and searching every weed for the tiny
sea-slugs. I do not deny that the result is worth the
trouble when some delicately tinted beauty rewards the
search, but the trouble is not slight. However, storms are
often kind to the ardent collector, and will toss up frag-
ments of weed covered with zoophytes, among which many
a prize may be found. Such fragments are always worth
careful study, if found in the fresh condition.
The first Opisthobranch we shall mention is the sea-hare
(Aplysia hybrida, see Fig. 71), an animal unfortunately rare
on the North-east Coast. I have found it between tide-
marks, but its habitat is among beds of weed in the
Laminarian zone, and especially among the blades of
Zostera — that strange marine flowering plant which grows
at many parts of the coast, and is the favourite refuge of
many curious animals. The sea-hare is an animal of
singularly curious shape, with a characteristic smell, and a
habit of pouring out a purple dye when alarmed. Round
the animal and the dye many curious superstitions have
clustered, especially in the Mediterranean, where the sea-
hares grow to a large size, and have been known from
ancient times. Those who are accustomed to argue that the
wide distribution of a belief is a proof of its validity, will
find some difficulty in fitting the sea-hare into their
philosophy. The belief in its poisonous qualities is wide-
spread, both among the ancients and among modern
fishermen. Just as the gathering of poppies, or "thunder-
cups," is likely to be followed by an avenging thunderstorm,
so the foolish naturalist who wantonly handles the sea-hare
will be smitten by fell disease. As far as my own experience
goes, I may say that I think the one consequence is as likely
to follow as the other, for the sea-hare is a perfectly harmless
250 LIFE BY THE SEASHORE.
little creature, chiefly remarkable for its strange contortions
and quaint shape.
So variable is the shape that the animal is not easy to
describe. There is also considerable variation in colour;
when young the whole animal is violet or purplish, while in
the adult state it is greenish grey, speckled and mottled
with brown and white. The shell is not visible externally,
and the body is dome-shaped, the slender head projecting
markedly in front. There are two pairs of tentacles, of
which the upper (t) are shaped like hares' ears, and bear
the small eyes at their bases. At the sides of the body two
large flaps, or epipodia (ep in Fig. 71), rise straight up, and
almost meet in the middle line of the back. If you fold
back the epipodium of the right side you will see behind it
the single gill, and
the curious grape-
t shaped gland
which secretes the
purple fluid. Be-
tween the epipodia
in the mid-dorsal
line lies the thin,
papery shell, al-
most entirely
covered by the
After Gosse. mantle. The foot,
as usual, forms a creeping surface, but both it and the
epipodia are very contractile, and in life are constantly
changing shape. When the animal is actively crawling,
the foot projects considerably behind the body. Such an
expanded specimen may measure from two to four inches
from tip to tip. Between the epipodia on the dorsal surface
there projects a siphon-like process of the mantle, which
leads from the anus to the exterior. On dissection it is
easy to find the heart lying in front of the gill, the curious
horny jaws in the mouth, and the gizzard armed with horny
plates.
The next genus we shall consider is the very large one
of Doris, including the true sea-slugs, or sea-lemons. By
recent authors this genus has been broken up into a large
number of small genera, but as we shall only consider some
THE SEA-SLUGS. 251
half-dozen species, it is not necessary for us to name these
new genera.
The first species is very large, and is common in most
places far out on the rocks. If at a low spring tide you go
far out on the rocks and look carefully down the narrow
clefts, you will probably see large weird creatures, yellowish
in colour, soft to the touch, and shapeless in appearance.
They often reach a length of over three inches, and are
broad and massive. If you can successfully extricate them
from the rock crevices, place your specimens in water and
watch them unfold. There is no trace of shell, external or
internal, and the branchial plume of Aplysia has also dis-
appeared. The body is elliptical and depressed, and the
head is not separated from it ; the mantle-fold of the Azygo-
branchs is also absent. The dorsal surface is covered by
what systematists call the cloak, or mantle, which is really
equivalent to the epipodia of Aplysia. It is closely covered
with round tubercles, and is strengthened by spicules.
Through two little holes in it the short conical tentacles
are protruded anteriorly. At the other end, also on the
dorsal surface, is the median anus, which is surrounded by
a circle of feathery "gills," not homologous with the gill
of Aplysia. They are nine in number, are large and tri-
pinnately cut, or fern-like, and can be completely withdrawn
into the body. The foot forms a bright yellow creeping
surface, and is as broad as the body. The upper surface
in life is often bright in colour, with patches of blue-green
on a yellowish ground. This is Doris tuberculata, the
largest of our British Dorids. Like other species it lays
white ribbons of spawn on the rocks, but the process
is more easily observed in some of the more abundant
species. I have not found it easy to keep in confinement,
but there is usually no difficulty in obtaining specimens for
examination, especially in the earlier part of the year.
The next species, Doris johnstoni (see- Fig. 72), is rarer,
but occurs occasionally between tide-marks. It is not very
much smaller, for it may reach a length of two inches, but
is readily distinguished by the different shape and the more
numerous gills. The body is convex in the centre and
markedly depressed at the sides; the dorsal surface is
covered with very minute tubercles, and is blotched with
252 LIFE BY THE SEASHORE.
brown on a ground colour of yellow or white. The dorsal
tentacles are short and broad, and there are also a pair of
slender oral tentacles at the sides of the mouth. There are
fifteen tripinnate gills.
The next species is much more beautiful and much
smaller. It is called Doris repanda, is usually about an
inch long, and is of a dead-white colour, with a row of
yellowish white spots down each side. The back is covered
with indistinct rounded tubercles, and there are only five
small gills. The oral tentacles are broad and flat and the
dorsal ones long, Like most of the smaller species, this
one can take advantage of the surface tension to creep along
the surface of the water back downwards, and is then a
FIG. 72. — Doris johnstoni. Note the gill-plumes and the dorsal
tentacles. After Alder and Hancock.
beautiful little object. The actively moving tentacles, the
delicate branched gills, and the translucent whiteness of the
tissues, make it a delightful occupant of an aquarium, but,
like most of the Dorids, it requires some care in confinement,
being apparently very sensitive to impurities in the water.
It is not uncommon under stones on the shore.
Another species is Doris bilamellata, which occurs in the
Firth of Forth in February and March in countless numbers.
It is no exaggeration to say that in these months the rocks
are simply whitened by these little creatures and their
spawn. They are not particularly pretty, and show no
brightness of tint as so many inedible or noxious insects do,
but seem to enjoy immunity from persecution to a very
marked extent. I have not found any shore animal which
will eat them, and even the sea-gulls seem to leave them
THE SEA-SLUGS. 253
alone. Possibly the slime with which they are covered has
something to do with their immunity. They have a curious
habit of congregating, not in pairs, but in clusters of three
to seven or so, and laying their eggs in continuous masses.
The eggs are embedded in a tenacious jelly analogous to that
which surrounds the eggs of frogs. By means of this jelly
not only are the eggs attached together to form a ribbon
about half an inch broad, but also one side of the ribbon is
sufficiently sticky to adhere to the rock surface, and as the
ribbons are laid in spirals, they stand up from the rocks like
ladies' frills. Such ribbons are found on the rocks during
almost all the colder months of the year, but are most
abundant in February and March.
You should not fail to obtain a small stone bearing spawn,
and carry it home with you to place in an aquarium. By
means of a lens you can make an attempt to estimate the
number of eggs in an inch of the ribbon, and so get an idea
of the countless numbers of eggs laid by each individual. A
few pages back we discussed the egg-laying habits of the
whelk, and noticed the wholesale sacrifice of eggs which
takes place within the egg-capsule. Nothing of the kind
occurs here. If you are successful with your spawn you
will find that from each egg a tiny colourless larva hatches
out, so that the water of your aquarium becomes cloudy
with the myriads of swimming specks. These larvae are
very diS'erent from the adults, and for a time are furnished
with the shell which the adult has lost, and with a power of
swimming of which the adult shows no trace. Stir the
water in your aquarium gently, and notice how at every
movement hundreds of larva? are thrown up on the sides of
the glass, there to speedily perish. Think of the wash of
the sea over the shore rocks, of the dangers from enemies,
and you will realise that, ruthless as the methods of the
young whelks seem, they are probably justified in their
results. It is probably better that many of the eggs should
be sacrificed to feed the few, if these few are thereby
enabled to remain within the egg-case until the early stages
of their development have been passed through, rather than
that all the eggs should be hatched in a condition when
their power of resistance to unfavourable conditions is very
slight. On the other hand, it should be noticed that the
254 LIFE BY THE SEASHORE.
existence of a free-swimming stage in Doris must facilitate
distribution. It is possible that the young may travel
distances impossible to the sluggish adults.
To return to the special characters of Doris bilamellata.
The body is about an inch in length and is greyish speckled
with brown; the back is covered with numerous large
unequal tubercles, and there are numerous simply pinnate
gills.
A prettier species is D. pilosa, which is also very com-
mon in the Firth of Forth, and is about the same size
as the preceding species. It is easily distinguished by its
markedly convex shape, and the dense covering of slender
soft papillae on the back, which give it a "pilose" appear-
ance. The colour is usually white, but is occasionally
brown or even black. There are from seven to nine large
gills which are not retractile, and the oral tentacles are
broad and flat.
All these species are more or less common on the East
Coast, and I have named them all because they are readily
distinguished, and are worth careful study. There are a
great number of other species, mostly rare or absent on the
East, but in the Firth of Forth all those mentioned can be
found without difficulty. They all occur also around the
coast generally.
While hunting for species of Doris, you are almost certain
to find an animal very like a Doris in appearance, but of
somewhat different shape, and of delicate pinkish colour.
The body is smooth, oblong, and elongated, the foot project-
ing markedly behind the cloak when the animal creeps. The
cloak is almost a quadrilateral, and has a distinct keel down
the centre. Its margin is reflected and indented posteriorly.
There are thirteen simply pinnate gills which are not re-
tractile. This is Goniodoris nodosa (see Fig. 73), a most
graceful little creature, usually pink, speckled with white,
but sometimes white or yellow. It reaches a length of
about an inch, and is abundant everywhere under stones.
The breeding season is in March (in the Firth of Forth),
when the animals congregate in large numbers, and lay
ropes of spawn, very different in shape from the frilled
ribbons of Doris. This species lives fairly well in con-
finement, and is a great addition to an aquarium, where its
THE SEA-SLUGS. 255
more active habits and graceful shape make it preferable to
most of the species of Doris.
The remaining Nudibranchs. are nearly all beautiful, both
in form and colour, but are so numerous that we can select
only those which are fairly common between tide-marks.
Unfortunately, none of them have common English names.
The first genus, Triopa, generally resembles Doris, but
differs from it in the reduction of the gills, now only three
in number, and the presence of slender outgrowths or
processes at the sides of the back. In Triopa daviger, our
only British species, the body is less than an inch long, and
is white, variegated with bright yellow, a combination of
colours which is very common among littoral Nudibranchs.
It is an inhabitant of deep water, and is only rarely found
between tide-marks.
FIG. 73.—Goniodoris nodosa. After Alder and Hancock.
Another form, Polycera quadrilineata, is not uncommon
near low-tide mark, and is singularly beautiful in appearance.
It is pure translucent white, beautifully marked and spotted
with, bright yellow and black, the yellow spots being
arranged in four lines running down the sides of the body.
The tentacles are non-retractile, and the head bears, in
addition to them, four to six processes, white tipped with
yellow in colour. There are seven to nine simply pinnate
gills, and close to the gills at either side a single golden-
tipped process. It is to these processes with their beautiful
colouring that the animal owes half its beauty. I have
found it not infrequently among zoophytes and corallines at
low spring tides. It grows to a length of about an inch.
A very similar but much smaller form is Ancula criatata
(see Fig. 74), which is common between tide-marks in the
256 LIFE BY THE SEASHORE.
Firth of Forth, especially in spring. Its colouring is similar
to that of Polycera quadrilineata, but there is only one
yellow line placed in the middle of the back. The yellow
tips to the processes are also often much less bright, the
animal at times being wholly white. It is easily dis-
tinguished from the preceding form by the arrangement
of the processes. These are absent on the head itself, but
the stalks of the dorsal tentacles each bear two. There are
three large bipinnate gills, and these are surrounded by a
circle of yellow-tipped processes, instead of the two of
Polycera quadrilineata. All these points are well shown
in the figure. The animals live well in confinement, where
they spend much of their time floating at the surface, back
downwards.
Fia. 74.— Ancula cristata. After Alder and Hancock.
The next form, Dendronotus arborescens, is regarded by
many naturalists as the most beautiful of our sea-slugs.
Its name and its beauty are both due to the fact that the
back is furnished with numerous branched and brightly
coloured processes, which make the creature look more like
a dainty piece of seaweed than a living animal. Bright as
the colours are, they harmonise wonderfully with the reds
and browns of the corallines among which the animal lives,
so that it is by no means conspicuous in natural conditions.
Like most sea-slugs it is rarely if ever eaten by shore
animals, so that the colouring, although it resembles the
surroundings, can hardly be described as "protective," and
it is certainly remarkable that colouring of this kind should
be common among animals apparently rarely attacked by
others.
THE SEA-SLUGS. 257
Although Dendronotus can hardly be described as com-
mon between tide-marks, I have not infrequently found
specimens there. They are, however, usually of small size,
while specimens from deep water reach a length of two
inches. As is the case with most of the shore inverte-
brates, the animals breed long before they attain the maxi-
mum size of the species, so that I have had specimens of
under an inch in length which laid numbers of eggs in
confinement. Facts of this kind are very apt to puzzle
novices accustomed to land animals, whose life is more or
less sharply divided into two parts — an early period of
growth, and an adult period of reproduction. It should
be clearly understood that such a condition of affairs is rare
among marine invertebrates, which have usually no definite
limit of growth, and which begin to reproduce very early.
The result of this is that statements as to size are often
very deceptive, for the limit given is usually that observed
by some authority on the particular group, and the animals
of the area at your disposal may show great variation as
compared with this standard. Thus in the Firth of Forth
the common starfish grows to a size much larger than the
limit usually given, especially when it occurs in the vicinity
of extensive mussel beds. On the other hand, in many
cases the sea-slugs which congregate for breeding purposes
are all distinctly below the standard of size as determined
for other areas. It is not perfectly clear why marine in-
vertebrates should differ so markedly in this respect from
terrestrial forms, but there is no doubt that on the whole
the conditions of life are easier on sea than on land. The
high specific gravity of sea-water renders the support of
the body an easy matter, while in a terrestrial animal, such
as an insect, living in a rare medium, any additional weight
would probably be a matter of great importance, and the
limit of advantageous size is fixed more or less precisely
for each species.
As to the special characters of Dendronotus, it has no
gills of any kind, and the body is elongated, narrow, and
prismatic in shape. The dorsal tentacles are placed in
trumpet-shaped sheaths, which are prolonged into branched
processes. Similar processes fringe the front of the head,
and are arranged in tufts down the back. The body is
s
258 LIFE BY THE SEASHORE.
some shade of red-brown, beautifully streaked and marbled
with white; the processes are also red or crimson, the
colour fading towards their tips as it does in most seaweeds.
The animals are very active, continually creeping and twist-
ing about. The eggs are yellowish in colour, and are laid
in a close spiral with very narrow coils. I kept a pair in
confinement for a long time, but rashly introduced a sea-
anemone (Actinoloba dianthus) into their aquarium. In
the course of their travels the sea-slugs crawled over part
of the anemone, and it forthwith discharged its stinging-
threads and killed the sea-slugs. They were not eaten,
being, indeed, almost as large as the anemone, but simply
killed, much to my sorrow, for they were beautiful pets.
It has been supposed that it is an important part of the
function of the branched papillae that they render Dendro-
notus and its allies inedible ; but I can hardly believe that
this is the whole explanation, for forms like Ancula cristata,
which have relatively few papillae and no brilliancy of
colour, are also severely let alone by most animals. The
aquarium in which the Dendronotus lived afforded some
interesting results as to relative immunity to attack. Its
chief occupant was a young Norway lobster of beautiful tint
and large appetite, not very easy to satisfy. It was fondest
of shrimps, prawns, and young crabs of various kinds, but
had a way of eating these rather trying to the feelings
of the onlooker, so I liberally supplied it with various sea-
slugs, of which at the time I had a large stock. Colourless
specimens of Ancula cristata, small Dorids, Dendronotus,
and others, which seemed less alive than crabs and quite
suited to the lobster's taste, were placed in his dish. But
though the coat of a young spider-crab was no protection
against the voracity of the Nephrops, the delicate sea-slugs
crawled untouched over his body, while he seemed only
anxious to get out of their way. When the anemone came
on the scene, however, the conditions were largely reversed.
The crabs seemed able to resist its deadly power to a much
greater extent than the defenceless sea -slugs, who fell
victims at once; but in natural conditions the sea-slugs
rarely live in those dark and dank localities which suit this
particular anemone. The experiment showed in an interest-
ing way that the value of a protective device depends upon
THE SEA-SLUGS.
259
the environment of the protected animal, and must have a
direct relation to this environment. It seems probable that
the sliminess of many sea-slugs, like that of some worms,
may render them unpalatable to many foes.
Much smaller than Dendronotus, but in its way quite as
beautiful, is Doto coronata, a little animal occasionally
found among corallines at the margin of the rocks. (The
animal is shown in Fig. 4, p. 13, and the spawn in Fig. 75.)
If you can pick it out from a dense cluster of the weed, you
may natter yourself that your eye has been tolerably well
trained. One specimen may be found by chance, but if you
are desirous of obtaining several for examination, you will
find the need of patience exceeding that of Job. Place
your specimens on green weed or in a light dish, and you
may wonder at their conspicuousness, put them back among
the corallines and zoophytes and they seem to disappear
from sight. Not only is there no definiteness of form, no
difference of colour to catch the eye, but the colours are so
arranged as to give that contrast of reddish pink and white
so eminently characteristic of
tangled tufts of coralline.
The body is very small, with
a pale ground colour and
crimson markings; there are
no gills, but the back bears
five to seven pairs of very
large papilla, each of which
is covered with large tubercles,
whose crimson colour stands
out against the light tint of
the papillae. The papillae are
often described as resembling
pine cones, and their shape
and markings give them an
apparent bulk out of all pro-
portion to the size of the
body. In confinement they
are very apt to fall off at the slightest touch. The tentacles
are very slender and spring from large trumpet -shaped
sheaths. The animal lives on zoophytes and is strictly an
inhabitant of deep water. I do not know the special value
Fio. 75.— Spawn of Doto coronata.
After Alder and Hancock.
260 LIFE BY THE SEASHORE.
of the resemblance to coralline, nor do I know what animals
attack it under natural conditions.
The next set of sea-slugs we shall consider belong to the
very large genus Eolis (see Fig. 76), whose members often
chiefly differ from one another in colouring, and are usually
exceedingly beautiful. All are characterised by the simple
slender papillae arranged in rows or clusters at the sides of
the back. Most of them live among weeds and zoophytes,
on the latter of which they chiefly feed. We shall consider
here only a few of the commoner species.
The common grey sea-slug (Eolis papillosd) is the largest
of our species, and may reach a length of three inches, but
is usually much smaller. The middle of the back is perfectly
smooth, and in small, delicate specimens it is easy to see the
beating of the transparent heart through the skin. The
sides of the body are densely clothed with closely set
papillae, arranged in more or less distinct rows, and usually
greenish or brown in colour. As in the other species there
are two pairs of tentacles — a dorsal pair, here short and
stout, and a ventral or oral pair beside the mouth. The
colours are variable, but usually not bright, and the papillae
so frequently fall off in confinement that the animal is
hardly a desirable occupant of an aquarium. From its
large size it can be dissected more readily than many of
its allies, and dissection will disclose the curious fact that
the stomach is much branched, its branches being continued
into the papillae.
The next species is much more beautiful, and is fairly
common between tide-marks on the North-east Coast. It
is called Eolis coronata, and is usually less than an inch
long. The body is proportionately much more slender and
elongated than that of the preceding species, and the
papillae are arranged in transverse rows across the back
instead of in dense masses at the sides. The dorsal tentacles
are what is known as "coronated," being surrounded by
spiral yellow projections of very characteristic appearance.
The oral tentacles are very long and slender, and the anterior
angles of the foot are produced. The body is a delicate
pinkish white colour, but it is to the papillae that the
animal owes its beauty. They are transparent, and traversed
through the greater part of their length by the branches of
THE SEA-SLUGS. 261
the stomach, the result being that each is bright crimson
in colour, tipped with white above the point where the
branches of the stomach stop. In another light, however,
the crimson part suddenly flashes out into the brightest
blue optical colour, with a sheen like that of a bird's feather.
In certain lights the little animal closely resembles coralline,
while in others the blue tints make it stand out vividly.
It is a most beautiful little species, and lives well in confine-
ment. I have found it not infrequently at low spring tides.
The next species — Eolis rufibranchialis — may justly be
described as quite common, at any rate in the .Firth of
Forth, where I have found numbers of specimens. It
generally resembles the preceding species, except that the
FIG. 76.— Eolis rufibranchialis. Note the processes, or papillae, on the back, the
two pairs of tentacles, and the minute eyes at the base of the upper tentacles.
After Alder and Hancock.
dorsal tentacles are transversely wrinkled, instead of
distinctly coronated, and the papillae bright red in colour,
with a white ring near the tips, and no trace of metallic
sheen. The body is white. This is a very hardy species,
and active in confinement. The general characters may be
easily made out from the figure.
There are a great many other species of Eolis on our
shores, but those named are the commonest, and may serve
to give an idea of the general structure and habits. Those
who desire to pursue their observations further should
consult the beautiful Monograph of the British Nudi-
branchiate Mollusca, by Messrs. Alder and Hancock, or
attempt to make a journey to the Newcastle Museum to see
the original drawings of the last-named, which are among
the treasures of the collection there.
262 LIFE BY THE SEASHORE.
The sea-slugs are in many ways a most interesting group,
and well worth careful attention. First as to structure.
With the exception of Aplysia, all those we have named are
without trace of shell; but this is not universally true of
Opisthobranchs, for some of them have well-developed
shells. The shell has indeed been gradually lost, as in so
many groups of Mollusca. Then, again, the sea-hare has a
typical gill like that of whelk or periwinkle ; Doris has a
circlet of many gill-plumes, and these gradually decrease in
number as in Polycera and Ancula, till we come to forms
with no gills at all. Simultaneously with the disappearance
of the gills we have the appearance and increase of the
curious papillae, branched as in Dendronotus, or simple as in
Eolis, which help to give the Opisthobranchs their quaint
and beautiful shapes. Similarly, we see in passing from
Aplysia towards the Eolids how the solidity of appearance
which we are accustomed to associate with our shore
Gasteropods gives way to a delicate translucency or trans-
parency, and the dull tints of whelk or periwinkle to soft,
bright colours, which are sometimes like those of the
surroundings, and sometimes markedly different from these.
Generally, we may say that the Opisthobranchs are a
specialised group of Gasteropods, which in some cases have
lost many of the Gasteropod characters, but which can be
shown to have originated from typical forms with coiled
shell, visceral hump, gill, and characteristic asymmetry.
THE SEA-SLUGS.
263
KEY FOR IDENTIFICATION OF ANIMALS DESCRIBED IN
THIS CHAPTER.
OPISTHOBRANCHS. Usually without shell, gill behind the heart.
(1) Shell present, one lateral gill.
Shell concealed, delicate, -\
single gill, 2 well- \Aplysia hybrida.
developed epipodia J
(2) Shell absent, gills plumose, placed round anus in mid- dorsal
line.
D. tuberculata, 9 tripin-
' nate gills, tubercles
numerous, round.
D. johnstoni, 15 tripin-
nate gills, tubercles
minute, close-set.
D. repanda, 5 tripinnate
gills, tubercles small,
distant.
D. bilamellata, numerous
simply pinnate non-
retractile gills, tubercles
large, unequal.
D. pilosa, 7 to 9 non-
retractile gills, mantle
with dense soft papillae.
Body ovate, depressed,'
mantle large, without I
processes, coveringhead \-Doris
and foot, dorsal ten-
tacles retractile .
Body elongated, mantle
small, without pro-
cesses, not covering
head and foot, dorsal
tentacles non-retractile
Body elongated, mantle
small, bearing lateral
processes, gills 3, tri-
pinnate
Body elongated, mantle"
indistinct, head with 4
to 6 processes, gills 7
to 9 with lateral ap-
pendage at each side .
Like Polyccra but with-
out head appendages,
except for 2 on the ten-
tacles, and with only 3
gills surrounded by pro-
cesses
Goniodoris
( Gf. nodosa, gills 13, simply
' \ pinnate.
Triopa claviger.
-Folycera quadrilineata.
Ancula, cristata.
264 LIFE BY THE SEASHORE.
(3) Gills absent, processes numerous, simple or branched, tentacles
with sheaths.
Body narrow elongated,^
CcTed, ™= k'"" arb°—
with branched sheaths]
Body narrow and small, \ ID. coronata, processes
Esses unbranched, In/ with 5 to 6 rows of
and massive, ten- [ tubercles and a ter-
5 in plain sheaths] [ minal one.
(4) Gills absent, processes linear or fusiform placed along sides of
back, tentacles 4 without sheaths.
(E. papillosa, 18 to 24
transverse rows of pa-
pillse, body broad.
Body elongated, tapering
1.
behind with numerous I Eolis
simple papillae or pro- J
cesses . . J
E. coronata, papillae in 6
to 7 clusters at each
side, dorsal tentacles
coronated.
E. rufibranchialis, dorsal
tentacles wrinkled, pa-
pillae red in 6 to 7
clusters.
OUTLINE CLASSIFICATION OF GASTEROPODS.
I. The Chitons, primitive forms very different from ordinary
Gasteropods.
II. Zygobranchs, limpet-like forms.
III. Azygobranchs, forms with coiled shell, single gill in front
of heart.
(a) Forms with unnotched shells, such as the periwinkles, the
tops, and others.
(b) Forms with notched shells, such as the whelks, dog-whelks,
and others.
IV. Opisthobranchs, forms often without shell, gill behind the
heart.
(a) Forma with shells (Tectibranchs). Of these only the sea-hare
has been described.
(b) Forms without shells (Nudibranchs), the different kinds of
NOTE ON DISTRIBUTION.
The sea-hare is commoner in the South than in the North, and is
said to be especially abundant at Weymouth and Torbay. Of the
remaining sea-slugs described in this chapter, certainly the majority
THE SEA-SLUGS. 265
occur all round the coast, though their relative abundance varies
greatly. In the West and South-west — as indeed everywhere to a
greater or less extent — other species occur between tide-marks, but
the forms mentioned may be sufficient to afford an insight into the
chief modifications of external form in the Nudibranchs. Certain of
the species of Doris are especially widely distributed and common. I
have found singularly fine specimens of D. tuberculata in abundance
between tide-marks, at such widely separated localities as Alnmouth
and Aberystwyth. Many of the Nudibranchs, indeed, seem to be as
universally distributed around our coasts as such familiar forms as
the common shore crab, the mussel, cockle, shrimp, periwinkle, but
in most cases the sea-slugs are less likely to be noticed than these.
CHAPTER XIV.
BIVALVES AND CUTTLES.
General characters of Bivalves — Their classification — The saddle-oyster
and the mussels — Their structure and habits — Oysters, Pectens,
and Lima — Swimming power of Pecten and Lima — Characters of
Cyprina — Mactra and its allies — The Venus and carpet-shells —
The cockles — The gapers— Mya and Lutraria— Rock-borers— The
cuttles.
THE next great group of the Molluscs is constituted by
the Bivalves, or Lamellibranchs ("plate-like gills"), of
which the oyster, mussel, and clam are familiar examples.
In order to get a notion of the anatomy, it is well to obtain
a living mussel and a living example of the bivalve known
as the little carpet-shell (Tapes pullastra), which is very
abundant on the rocks. The blue shells of the former,
and the brownish yellow ones of the latter, are very
common objects on most shores. Place both in water, and
notice the two valves of the shell, united to one another
by an area of greater or less extent known as the hinge.
Notice that when the animals are at rest the valves gape
slightly, allowing certain of the soft parts to protrude. But
when alarmed they close their shells suddenly, sometimes
sending out a sudden jet of water in the process. The way
in which the shell is closed enables you to conclude at once
that it must be the result of muscular action ; there are, in
fact, large closing muscles, usually two in number, in all
Bivalves, and they are very characteristic structures.
Next study carefully the parts protruded in an open
bivalve. Take the mussel first (see Fig. 77). As the shell
gapes there appears at the part of the shell opposite the
hinge a fringed mantle-flap (i in Fig. 77), which is double
266
BIVALVES AND CUTTLES. 267
in correspondence with the shell whose valves it lines. At
the straighter side of the shell there is protruded a slender
white foot (/ in Fig. 77), by means of which the animal
slowly moves. If allowed to remain undisturbed it ulti-
mately anchors itself by a rope of threads, or byssus (b in
Fig. 77), secreted from the foot, and serving to fasten the
animal to the surrounding stones or shells. The byssus is
rapidly formed,
and can soon be
renewed if torn
away. At the
side of the shell
opposite to the
foot it will be
seen that the
two parts of the
mantle are fused
together at two
places a little ^ia- ^ — Edible mussel (Mytilus edulis). For letters
distant from one
another, so that a very short tube (e in Fig. 77) is formed.
By placing the mussel in slightly turbid water, it is easy
to see that in life there is a continuous current of water
entering by a wide space between the halves of the mantle
marked i in Fig. 77, and leaving by this short tube, which
constitutes the exhalent aperture. The lower current brings
with it food particles and the oxygen necessary for respira-
tion, the upper current carries out the waste carbonic acid
and the indigestible residue of the food.
Turn next to the little Tapes, and you will find very
similar conditions, save that the foot is of a different shape,
and the two apertures are drawn out into long siphons or
tubes, which can be protruded or retracted, and whose tips
are beautifully fringed. A little observation will show that
by the upper of these the water escapes, while it enters by
the lower. Again, while the mussel must live freely ex-
posed to the water, the carpet-shell, on account of its
siphons, is enabled to live buried in sand or mud with
merely the siphons protruding. Eefore proceeding to re-
move the upper valve of your specimens to examine the
anatomy, study some empty shells of the same or different
268 LIFE BY THE SEASHORE.
species. In the mussel notice first that the two valves of
the shell are of the same size (equivalve); this is very
characteristic of Bivalves, and, together with the fact that
each valve is inequilateral, is a convenient means of dis-
tinguishing them from Brachiopods, or lamp-shells, which
have inequivalve but
equilateral shells. In
other words, the shell
of a bivalve is divided
into two equal parts
when the valves are
separated, but not
when the valves are
divided by a median
pi°- n--^r££™^°».ia™eut 1ine\.TheJ she11 rf *
Brachiopod, on the
other hand, consisting as it does of two valves of unequal
size, is divided into two equal parts only by a line which
bisects the two closed valves.
Again, the two valves of the shell of the mussel are
united at the hinge by an internal cartilage called the
ligament, so placed as to cause the shell to gape, except
when it is forcibly closed by muscles. The hinge is over-
hung by two projections, or beaks, which form the oldest
part of the shell. In the inside of the shell are to be seen
markings indicating the places where the muscles of the
shell have been attached. In the mussel these are two in
number, and are placed at the side of the shell opposite to
that where the foot is protruded. In addition to these
markings, there is an uninterrupted line near the margin of
the shell which marks the line of attachment of the mantle
to the shell. If the mussel shell be compared with that of
Tapes, it will be seen that in the latter case this line of
attachment does not follow uninterruptedly the margin of
the shell, but is at one spot inflected to form a deep,
rounded bay, called the pallial sinus. This sinus marks the
attachment of the muscles which move the siphons, and its
presence in a shell enables one to conclude at once that the
living animal possessed siphons.
The shell of Tapes differs in several other respects from
that of Mytilus. Thus the hinge, instead of being smooth,
BIVALVES AND CUTTLES. 269
is furnished in each valve with three projections, or teeth,
which lock into corresponding cavities, in much the same
way as that in which the bones of the skull in a mammal
are locked together. Further, the ligament in Tapes is
outside the shell, instead of being within it, and the two
muscle impressions are more distinctly marked than in the
mussel.
Having by the study of the shell determined the position
of the closing muscles, kill your living specimens by dropping
them in hot water, slip a knife in between the valves, and
cut through the muscles as close to the shell as possible.
As soon as this is done, the elasticity of the ligament will
cause the shell to gape, and the upper valve can be gently
removed. If this be done carefully in both mussel and
Tapes, the animal in each case will be seen lying covered by
its mantle-flap, with the foot projecting more or less at one
end, and the apertures, or siphons, distinct at the other.
There is no head, but the mouth is placed at the opposite
end to the apertures, or siphons, and usually lies at the
more rounded end of the shell. It is immediately in front
of the foot, and has two little flaps, or palps, at either side.
On lifting up the mantle there will be found the plate-like
gills, of which a pair lie at either side of the foot. Pro-
jecting through the softer tissues will be also seen the firm
closing muscles cut through when the shell was opened, and
the foot, small in the mussel but large and distinct in Tapes,
as in most common Eivalves.
"We cannot enter in detail into the anatomy of the
Bivalves — they are difficult to dissect and to understand —
but it may be well to explain briefly what structures vary
most frequently, and on what the usual classifications are
based. In the first place, there is much and very obvious
variation in the shell, in its shape, colour, and finer details.
Almost all early classifications depended on the shell. But
we have seen that the shell affords clear evidence as to one
structural characteristic of the living animal, the absence or
presence of siphons, so that a very early division is that into
siphonate and asiphonate forms. Again, in some cases, as
in Tapes, there are two distinct closing muscles, while in
others one only is present. As this character can also be
determined 'by the examination of the shell, it is very
270 LIFE BY THE SEASHORE.
frequently used in the classification of Bivalves. Finally,
the gills vary much in structure, being sometimes composed
of free filaments, and at others woven into more or less
compact, plate-like structures. We shall adopt here a
classification based on this difference in the gills, for the
following reason. There can be no doubt that the existing
Bivalves have been derived from forms similar to, but
simpler than, the less specialised of existing Gasteropods.
The early Bivalves must have had simple, plume-like gills,
similar to the gills of many Gasteropods, and the more
complicated the gills of present Bivalves, the further have
they departed from this primitive condition. The most
natural classification seems, therefore, one based on the gills.
As, however, we shall consider only such Bivalves as are
likely to be found in the living condition, or are very
abundant in the dry condition on the shore, we shall
consider only three orders: (1) the Filibranchs, those with
filamentous (or thread-like) gills such as the common mussel;
(2) the Pseudo-lamellibranchs, those like the scallops, which
have gills apparently of plate-like structure, but with the
separate filaments so slightly attached that they fall apart
very readily; (3) the Eulamellibranchs, the great majority
of Bivalves in which the gills are firm plates, whose
constituent filaments cannot be readily separated from one
another.
The first order includes the curious little saddle-oyster
and the mussels, together with other forms which need not
be considered here. The saddle - oyster, or silver -shell
(Anomia ephippium), is common under stones between tide-
marks, and exhibits several peculiarities of structure. The
shell is fragile, pearly white in colour, and often irregular
in shape. It consists of an upper convex valve, and a lower
flat one perforated by a large hole beneath the beaks. The
animals are extremely sedentary in their habits, growing
fixed to rocks, but the fixation is accomplished in a some'
what peculiar way. We have already explained that most
Bivalves possess a byssus gland in the foot, which secretes
a mass of silky threads serving to anchor the animal to
surrounding objects. The saddle-oyster also possesses this
characteristic gland, but both it and the foot are much
reduced and apparently functionless. But nevertheless the
BIVALVES AND CUTTLES. 271
animal does fix itself firmly to rocks, and it is of interest
to notice how it accomplishes this. Of the two adductor
or closing muscles which most Bivalves possess, one is here
very rudimentary, while the other is large and conspicuous.
From this large muscle a slip arises which passes through
the hole in the lower valve of the shell, and is attached
to the rock. Its end is furnished with a curious limy disc
or operculum, formed by an aggregation of many little
plates. In the living animal the shell, as usual, gapes to
allow for the entrance of the necessary currents of water,
and there is also, owing to the relaxed condition of the
attaching muscle, a space between the lower valve and the
rock. When the animal is alarmed the muscle contracts
suddenly, the result being not only to close the valves,
but also to drag the lower valve close against the rock.
You will appreciate the meaning of this best by trying to
peel the animals off the rock with your fingers, after they
have been thoroughly alarmed. The method of attachment
is very interesting, and offers some curious problems in
origins to those speculatively inclined. Why should the
saddle-oyster have given up its original method of attaching
itself by a byssus? And if its peculiar method is advan-
tageous, why should other sedentary forms have not adopted
it ? There are many similar questions which one may ask,
though I do not know if they can be answered at present.
Saddle-oysters are very abundant on the shore, but on
the East are usually of small size, the shells being often
under half an inch in diameter. From their habit of closely
accommodating their shells to the irregularities of the rock
surface, they are very apt to be overlooked by careless
observers.
We come next to the mussels, familiar forms, unfor-
tunately burdened with a plethora of names. We shall
describe three species, placed in as many different genera,
viz. the edible mussel (Mytilus edulis), the horse -mussel
(Modiola modiolus), and the marbled Crenella (Crenella
marmorata). All three are nearly related, and are some-
times placed in the same genus, or given other generic
names. All are common, and may easily be found in the
living state.
The edible mussel is easily recognised, and has already
272 LIFE BY THE SEASHORE.
been in large part described. It occurs in small numbers
on most parts of the coast, but in favourable situations
forms great mussel beds which are often carefully preserved,
and are of considerable commercial value. Before the
mussels can multiply with sufficient rapidity to form these
beds, they must have abundant food and a suitable sub-
stratum. For food they seem to depend largely on the
finer refuse brought down by rivers, and they rarely nourish
except where food of this kind is abundant. Where it is
abundant, however, they occur in numbers which are liter-
ally countless, as everyone who has seen a healthy mussel
bed must know. In one respect such beds are peculiarly
deceptive, as the unwary naturalist is likely to speedily
discover. My own first introduction took place in the
Firth of Forth, where a very low tide had laid bare a long
stretch of thickly covered rocks, dotted here and there with
huge starfish. Mindful of the tide, I hastened outwards
with more speed than discretion, and, planting a hasty foot
on a patch of mussels, found that it sank downwards over
the boot-top in a mass of fine mud before it reached the
firm rock. Later I learnt that this mud may reach a depth
of many feet; so that it is distinctly unwise to rashly under-
take the investigation of mussel beds. What happens is
this — the mussels attach themselves to a smooth rock, and
by means of the fine cilia (whip -like threads) on the
surface of the gills and mantle produce rapid inhalent
currents. If the water contains many suitable solid par-
ticles they flourish apace, digesting these, and passing out
the indigestible residue in the form of fine mud. This mud
accumulates rapidly and would soon stifle the mussels, were
it not that as it is deposited they gradually lengthen their
attaching threads, so that they rise above the surface of the
rock. In still water the process may go on until the byssus
threads reach a length of several feet, the space between
the shell-fish and the rock being occupied by a mass of
solid mud. The result is that although a flourishing mussel
bed may be both useful and valuable, it is neither pretty
nor sweet-scented.
The large horse-mussel does not, strictly speaking, live on
the shore rocks, but young forms are common there, and the
shells of the adult are not infrequently found on the sands.
J BIVALVES AND CUTTLES. 273
The shell is larger and stouter than that of the edible
mussel, and may be distinguished from the latter by the
fact that the beaks are not terminal, but slightly to one
side. The colour is very dark blue, almost black, and the
shell is covered by a translucent membrane, or epidermis,
which in the young is prolonged into a fringe. The byssus
is very strong, and the animal entangles with it shells and
small stones, so as to form a kind of nest. It lives usually
in sand or mud in comparatively shallow water.
The third mussel is a much prettier species, whose habitat
renders it peculiarly interesting. The edible mussel spins a
rope by which it fastens itself to stones or posts, the horse-
mussel uses its threads to weave foreign objects into a
protective nest, but Crenella marmorata finds shelter and
safety within the tests, or outer coats, of sea-squirts
(Ascidians). Into these it burrows deeply, so deeply that
its presence can only be discerned by the resistance which
the Ascidians offer to the touch. Ascidians of various kinds
are common on most shores, often growing in masses beneath
overhanging rocks. Frequently, also, they are torn up by
gales, and strewn in repulsive-looking masses along the
shore. If your ardour is not quenched by an unfavourable
exterior, and is sufficient to lead you to tear open the tough
cases, you are likely to find not only the curious Ascidians
themselves, but also one or two specimens of the pretty
green Crenella marmorata. It also occasionally occurs in
nests like those of Modiola modiolus made of shells or
stones. The shape is very characteristic, the shell being
markedly gibbous, or swollen, and rhomboidal in shape.
It is sculptured by fifteen to eighteen longitudinal ribs
anteriorly, and by twenty to twenty-five posteriorly, the
ribbed areas being separated by a smooth region. The
beaks are small, swollen, inflected, and divergent. The foot
is white and very long, and is used in leisurely progression,
as well as in secreting the byssus threads.
In the next order, the Pseudo-lamellibranchia, are included
some exceedingly beautiful forms — indeed, I have heard it
maintained that one of them, Lima Mans, is the most
beautiful of our common marine animals. Others of them,
such as certain of the scallops, have always been prized by
shell collectors for the bright colouring of their shells,
274 LIFE BY THE SEASHORE.
which are usually marked in shades of red and pink. We
shall consider in the order only three genera — Pecten, Lima,
and Ostrea — all characterised by the structure of the gills,
the absence of siphons, the single adductor muscle, and
some other common characters.
Of the scallops the most abundant is the common scallop
(Peden opercularis), often seen in fishmongers' shops in the
larger towns. There are few stretches of sandy shore where
the separate valves of this species are not to be found, but
living animals are not quite so easily obtained. Those sent
to market are obtained by dredging, but where, as in the
Forth, there are large scallop beds, it is quite common to
find small living specimens on the shore rocks. After
storms, also, living scallops are often cast up in large
numbers on the shore, or are found living in the rock
pools. Such specimens are often somewhat injured by their
journey, and rarely live long in confinement, but small
specimens from the rocks live well, and form charming pets.
Select a few specimens about the size of a penny-piece, and
carry them home to your aquarium, or domicile them in
some rock pool. While you are admiring the beautifully
sculptured and coloured shell, its valves will suddenly gape,
and from the semicircular space so produced long, white
threads will be protruded, which float freely in the water.
Watch the opening shell carefully, taking care that your
shadow does not fall on the water, and you will see that the
two fringed mantle-folds are set round with — jewels I would
say, did not strict accuracy compel me to call them simple
eyes. But jewels they are, nevertheless, if changing tint,
with gleam of emerald and amethyst, may earn the name.
It would not be easy to say how much the scallop really
sees with them, but it is certain that it very speedily becomes
aware of differences in the intensity of light, or of rapid
movement. When it is alarmed in this way, it suddenly
changes its position by flapping its valves together in a way
which drives it through the water in a series of rapid jerks.
This power of swimming is very characteristic of the
scallops, and is a very curious sight. As they rest in the
bottom of the pool or dish, they look as passive as any other
bivalve, and when without apparent stimulus of any kind
these passive shells suddenly spring upwards in the water,
BIVALVES AND CUTTLES. 275
and by a succession of movements drive themselves a very
considerable distance through it, the astonished onlooker is
apt to receive something of a shock. It should be noted
that the movement is not accomplished by the foot — the
characteristic organ of locomotion in the Mollusca — but by
shell and mantle. Nevertheless, just as Anomia has a small
attaching byssus, although it attaches itself by another and
quite different organ, so the scallop has a foot, although it is
not used in locomotion. When your little scallops lie
motionless at the bottom of the dish, you may see the
slender, finger-like foot protruded at one side. It is capable
of spinning a slender byssus, by means of which the animal,
especially when young, temporarily anchors itself.
When you have studied the living animal, and watched
its curious flight, you should collect a goodly number of
shells from the shore and proceed to study them in detail.
It is well to have a considerable number of specimens, for
there is a large amount of variation, especially in colour — •
indeed, there are said to be no less than six colour varieties
in the Firth of Forth alone.
If your specimens consist, as often happens, of detached
valves, you should first pick out and distinguish the upper
and lower valves. Both valves are convex, but one is more
convex than the other, and in natural conditions it is the
less convex which is the upper. The difference between
the two valves is, however, not marked, and the shell is
therefore described as sub-equivalve — that is, with nearly
equal valves. It is also almost circular (sub-orbicular) and
almost equilateral. Like that of all other Pectens, or
scallops, it is furnished with two ears, here almost equal
in size, and has a straight hinge line with a marginal
ligament, and a central cartilage placed in a pit beneath
the beak of each valve. The special characteristics of the
species are found in the number of the ribs (about twenty)
and the peculiar structure of the surface of the shell. It
is covered with close rows of minute scales, which require
some little attention before they can be seen, but once the
shell has been closely studied it is almost impossible after-
wards to mistake the species for any other. In the
commonest colour variety the shell is red-brown marked
and spotted with white.
276 LIFE BY THE SEASHORE.
The common scallop is not the only edible species of
Pecten^ for the much larger P. maximus, often called a
clam, is not infrequently seen exposed for sale. It is a
very handsome species, reaching a size of six by five inches,
and often of a pale colour beautifully mottled with pink.
The valves are very unequal, the lower being deeply convex
and the upper almost flat, except for a slight concavity near
the beak ; it is always much darker in tint than the lower
valve. The convex lower valve bears fourteen to sixteen
broad, rounded ribs, wider than the spaces between them.
In the upper valve the relation of ribs and spaces is reversed,
so that the two valves lock closely together, a condition
which may be noticed in many Bivalves. The ears are
nearly equal, but are concave in the upper valve and convex
in the lower. The surface of the shell is quite without the
scales of the preceding species, but is marked by distinct
radiating striae, which with the broad ribs are very character-
istic of the species. Separate valves of this species are not
uncommon on the shore, but I have never found the entire
animal, either living or dead. Specimens for dissection may
be obtained at times from the fishermen. The shells are
sometimes used by cooks, and are very commonly sold in
fishmongers' shops at a penny apiece, but unfortunately it
is usually only the convex lower valves which can be
obtained in this way.
We shall mention one other species only, one which is
interesting because, like the oyster, it is fixed when adult,
and, as in the oyster, the shell is often curiously distorted.
This is P. pusio, odd valves of which may be often found on
the shore. The animal is attached by the lower valve,
which is usually white, without sculpture, and often of very
irregular shape. The upper valve has its surface covered
with very numerous (40-80) prickly ribs, often alternately
large and small. In the young the ears are unequal in
size, and in the adult they become very irregular.
The next genus is the very beautiful one of Lima, of
which we shall consider one species only — the delicately
tinted L, hians. Strictly speaking it is beyond our range,
but is such an interesting and beautiful species, and so
common in the Clyde, that we must make an exception in
its favour. In it the shell is snowy white, and the mantle a
BIVALVES AND CUTTLES. 277
lovely pink. It swims in a way which casts the efforts of
the scallops into the shade, and as it jerks rapidly through
the water it trails behind it a long mantle-fringe of rosy
pink, forming altogether a picture which once seen is
not easily forgotten. My own first experience of it was a
memorable one. It was on my first dredging expedition,
and the scene was the broad waters of the Clyde. The
wind blew strong and fresh, dashing the salt spray over the
side of the little yacht, as she heeled under the pressure of
her heavy dredge; but it was not strong enough to damp
the ardour of the enthusiasts, who clung desperately to any
available rope in their anxiety lest some treasure should
escape their notice. There were many treasures in the
heavy net, but perhaps the greatest were the rough-looking
masses of stones, shells, and weeds fastened together by
byssus threads, which we were told were the nests of Lima.
When carefully broken, these nests disclosed the animal
itself lying snugly in the centre. They were dropped into
jars of clean water, and instantly began to swim rapidly,
trailing their beautiful fringes behind them. They would
be beautiful in any situation, but seen against a background
of blue hills, with the fresh breeze in one's face, the blue
waters around, and the rocking boat beneath, there was
certainly an added charm. For my own part I cannot
think that a thousand daffodils can be so fair a sight as half
a dozen Limas, let the yellow bells dance never so merrily.
The memory of that first day has at least made the animals
particularly dear to me.
This particular species, L. Mans, does not occur on the
East Coast, so a journey must be made to the "West to find
it. The shell shows much general resemblance to a scallop,
but is longer in proportion to its breadth, and has less
prominent ears than most scallops. The shell gapes at both
sides, and is marked by numerous fine radiating lines,
crossed by other concentric lines. The animal also shows
much resemblance to a scallop, but its tentacles are much
longer and more numerous, and the curious habit of nest-
building also affords a contrast. Except in the extreme
South the animal is confined to deep water.
The third genus of the order, that of the oyster, is of
more interest to the epicure than the shore naturalist. The
278 LIFE BY THE SEASHORE.
edible oyster (Ostrea edulis) is related to the scallops, but
differs in its peculiarly sedentary habit with which is asso-
ciated the distorted and ugly shell, in the entire absence of
foot and byssus, and in some other characters. Just as
many domestic animals acquire their culinary value at the
expense of almost all the qualities which make them in-
teresting to the naturalist, so the oyster pays for its valued
qualities by the absence of the beautiful shell, the power of
active locomotion, the quick senses, and the other qualities
which make the Pectens and Limas so fascinating. Those
who are not epicures may perhaps be forgiven for regarding
a luscious oyster as about as attractive as a prize pig,
while . those to whom it. appeals as an article of diet will
probably mourn with the famous conch ologist that oysters
grew and died in countless numbers before ever men
existed to enjoy them. There can be no difficulty in recog-
nising an oyster if one should be found, which is not very
likely. The chief point of interest is the curious shapes
which the shells assume when subjected to pressure by sur-
rounding objects. The animals are incapable of locomotion,
and^are attached by the surface of the lower valve, for the
ftyssjijs gland has been completely lost.
tf-'*rFtS». third order of Bivalves, the Eulamellibranchia, in-
cludfe$ the greater number of living forms. Its members
are classified according to the presence or absence of the
siphons, the amount of union of the mantle-folds, the
characters of the gills, and some other points. Most of
them live buried in sand or mud, and the development of
siphons is an adaptation to this habit. Their degree
of development is reflected in the shell in the condition
of the pallial sinus (see p. 268), and where, as in the My as,
they reach a great size, they cannot be completely with-
drawn into the shell, and this "gapes" permanently. From
the habitat — usually sand or mud — these Bivalves are rarely
conspicuous on the shore rocks ; many may be obtained by
systematic digging near low-tide mark, others are tossed on
the beach after storms, but the majority, even of the
shallow-water forms, are familiar only in the condition of
shells. As our concern here is rather with living animals
than with "shells," we shall describe relatively few Bivalves,
chiefly those which may be hoped for in the living condition.
BIVALVES AND CUTTLES.
279
).— Left valve of shell of Cyprina islandica, to
show markings of interior, b, beak of shell ; t, one
of teeth ; o, anterior adductor muscle ; p, posterior
adductor ; I, ligament ; m, mantle-line.
As an example of one of the simplest Eulamellibranchs
we may take Cyprina islandica (see Fig. 79), which is often
very abundant in the living condition after storms. It has
practically no siphons, the mantle-folds are widely open, and
the pallial line is
simple, without
trace of sinus. The
shells are large,
triangularj and
convex; they are
sometimes used as
scoops, and .called p
"sugar - shells."
The surface of the
shell displays ad-
mirably a struc-
ture which we
have not yet ex- Fm.
pressly noted, and
that is the layer
called by conch-
ologists the epidermis. The shell of a Mollusc is made
of three layers, an external organic layer without lime, the
epidermis, a prismatic layer forming the bulk of the shell,
and an internal pearly layer, often absent, but sometimes
very well developed. In many shells the epidermis is early
rubbed off, exposing the prismatic layer, which is often
brightly coloured externally; but in Cyprina it is thick and
persistent, giving the shell its characteristic brown colour.
The shell is heavy and massive, obliquely triangular, and
swollen towards the beaks. It is marked by numerous fine
concentric lines, and is covered by the brown epidermis.
The teeth are well developed, there being three cardinals,
or central teeth, in each valve, and a single lateral. The
interior of the shell is smooth and chalky white. This
combination of characters makes the species readily recog-
nisable. The animal lives in muddy sand, in which it
burrows by means of the large foot. It is sometimes used
as bait.
In the next sub-order, which includes such important
genera as Mactra, Tellina, and Donax, the siphons are long
280 LIFE BY THE SEASHORE.
and the pallial sinus deep. Of the three genera named,
the species of Mactra are most commonly found in the
living condition, and are also very common as shells on the
beach at all seasons. Two of the species, M. solida and
M. subtruncata, are very much alike, and not easy to dis-
tinguish from a description merely ; while the third species,
M. stultoruwi, or Fool's Mactra, is readily recognised, and
cannot be confused with any other shell. In all cases the
shells are triangular, and are characterised by the almost
smooth surface and the nature of the teeth. Of these there
are two thin cardinals in the right valve, and two similar
but united cardinals in the left; the laterals are large and
laminar, there being two on each side in the right valve
and one on each side in the left. In Mactra solida the
shell is solid, opaque, and perfectly triangular, the sides
being equal ; the surface is marked by concentric striae and
is yellowish white in colour, often stained by substances
derived from the sand. It is not easy to point out dis-
tinguishing differences from M. suUruncata, but the latter
is smaller, more convex, and seems to be hollowed out at
either side of the beaks, so that
these become more prominent. In
M. stultorum the shell has the same
shape as in M. solida, but is thin,
delicate, glossy, and almost smooth.
The colour is a pale brownish tint,
variegated by longitudinal rays of
reddish brown. The shell is very
familiar, and is represented in all
FIG. 80. — Mactra stultorum. ,-, •,, ,. « * •, ., , ,,
the collections of children; the
other species, on the other hand, being thick and clumsy,
are often neglected.
As members of the same sub-order we may mention two
other forms, abundant as shells, but not commonly found in
the fresh condition. One of these is Donax vittatus, the
purple toothed-shell, an active little form which lives in
sand near low-tide mark, whose shells are greatly prized
by children both for their beauty and colour varieties. The
living animal is both interesting and beautiful, the foot
being large in proportion to the body, the mantle delicately
fringed, and the siphons, which are quite separate, marked
BIVALVES AND CUTTLES. 281
with longitudinal lines and delicately fringed at the tip.
The shell is small, at most an inch long, and some half-inch
broad. It is oblong and beautifully glossy and polished,
the surface being marked by fine longitudinal striae. The
inner margin is strongly notched, and the inside of the shell
is usually stained with violet. The colours of the outer
surface are varied, usually shades of violet, brown, or
yellow, but it is sometimes almost white.
An even prettier and more delicate shell is the little
Tellina tenuis, which, thin and fragile as it is, is often
tossed up intact after a storm. The shell is often pure
rose-pink, sometimes pure white, sometimes yellow or
orange. It is so much flattened that one might fancy the
animal would hardly have room to live inside, and so thin
that it can hardly afford much protection. The ligament is
very thick and prominent, the teeth small. The shell is
oval and semi-transparent. There are various other species
of Tellina, some of them common but mostly small, and
not to be found in the living state.
Another sub-order includes the Venus and carpet-shells, of
which there are a number of species. The species of Venus
are very numerous, and can be recognised by their triangular
or rounded shells with distinct concentric ribs. It may,
however, be sufficient if we name one species, common at all
seasons as a shell on the shore, and to be found living in
sandy places. This is Venus striatula, a small shell measur-
ing about an inch each way. The animal has fairly long
siphons united for the greater part of their length, a thick
foot slightly bent, and mantle-folds open in front. The
shell is pale-coloured, but usually marked by three bright-
coloured longitudinal rays of reddish tint, which cross the
strongly marked concentric ribs. A point of interest about
the animal is that it seems to be greatly relished as food by
some of the whelks, for most of the shells found on the
shore are perforated near the beak, showing that the whelk
has drilled a hole through it, as a preparation to the devour-
ing of the contained animal.
Of the little carpet-shell (Tapes pullastra) we have already
spoken ; it occurs very commonly on the rocks in sandy and
muddy places. The shell is rhomboid in shape and solid in
texture; it is marked by very numerous close set bands
282 LIFE BY THE SEASHORE.
crossed by fine longitudinal striae. The colour is yellowish
white, variegated with reddish brown. There are three
cardinal teeth in each valve. A prettier species with more
distinctly marked ribs, and streaks and patches of bright
colour, often occurs on the shore in the dead condition.
This is T. virgineus, which inhabits somewhat deeper water
than the common species. The latter lives well in confine-
ment, and affords an admirable object for the study of the
siphons. When alarmed, the animal suddenly retracts these,
producing a very forcible jet of water as it does so ; when it
is lying undisturbed the course of the breathing currents
can be clearly seen, especially in water containing suspended
particles.
The next sub-order includes the cockles, which have a
greatly elongated foot, used in taking "leaps," and also in
burrowing in the sand. There are a considerable number of
cockles, but as the differences between the species are not
very well marked, it may be sufficient if we describe the
common, or edible cockle (Cardium edule). This species, as
is well known, occurs in beds in sandy and muddy ground,
living on, or only slightly below, the surface. It is valued
both as food and bait, and is collected by the fisher folk in
large quantities, short rakes being used for the purpose. The
shell is equivalve, somewhat triangular, and strongly convex.
The characteristic cockle appearance is produced by the sculp-
ture, which consists of twenty-four to twenty-eight flattened
ribs separated by narrow furrows. These ribs project at the
margin, as in all cockles, so that the valves lock closely
together; in the living animal the mantle is fringed with
delicate processes corresponding to these ribs. In an empty
shell the internal characters can be made out, the fluted
margin, the muscle scars, the strong central (cardinal) tooth
in each valve, shaped like a reversed V, and the small
laterals at each side of this. The different cockles are
distinguished chiefly by the sculpture of the shells, and the
number and shape of the ribs; generally speaking all are
readily recognised as cockles.
We come next to two genera whose members show some
marked resemblances, combined with distinct differences. In
both the large siphons cannot be completely retracted, so that
the shell "gapes" permanently, and cannot be closed.
BIVALVES AND CUTTLES. 283
The first genus — the old maid shells, or Myas — includes
two common species which live buried in sand near low-
water mark, and often occur in large numbers on the beach
after storms ; the empty shells are to be found at all seasons.
In both the siphons are large, invested in a common sheath,
and united throughout their length. The shell is oval or
oblong, and gapes at both ends. The hinge -cartilage is
wholly internal, and is placed between a cavity in the right
valve and a hollow in a conspicuous process of the left
valve. The internal position of the cartilage and the
presence of the large cartilage in the left valve make the
shell of a Mya easily recognised. The shells are solid,
opaque, not glossy, and with little brightness of tint. The
FIG. 81. — Mya truncata, showing siphons and foot.
two species are Mya arenaria and Mya truncata, chiefly
distinguished by the shape of the shells. In M. arenaria
this is oblong, and about twice as long as broad; in
M. truncata it is oval, and the length bears to the breadth
about the proportion of five to four. In the latter, further,
the posterior end of the shell is abruptly truncated ; in the
former it is wedge-shaped. Both are used as food and bait,
and are greatly relished by seagulls, who may be found
feasting on them after storms.
The other genus includes the otter-shells (Lutraria), of
which we have one common species, L. ettiptica, which
inhabits the same localities as the Myas, and is to be found
with these after storms on the shore. The siphons are very
long, and are inclosed in a common sheath, but are not
completely united. As in Mya, the shell gapes at both
ends, but it is much thinner, and is glossy and brightly
coloured. The shape is elliptical and compressed, the car-
284
LIFE BY THE SEASHORE.
tilage internal placed in a deep pit, the teeth consist of two
diverging cardinals in each valve and two rudimentary
laterals.
We come next to the razor-shells, or Solens, interesting
Bivalves which cannot be confused with
any others, and which are very common,
though not often seen in the living
state. They live near low-water mark,
where they burrow deeply in the sand,
but may be readily dug out by an expert
digger. We have two common species —
Solen siliqua (see Fig. 82), the common
"razor-fish," in which the shell is almost
straight and the ends are both abruptly
truncated, and S. ensis, which is much
smaller, distinctly curved, and has the
anterior end more rounded than the
posterior. It is unnecessary to describe
the shell, for this must be familiar to
everyone ; but it should be noticed that,
like those of Mya and Lutraria, it gapes
widely at both ends. The shape of the
foot is interesting, and its efficiency as
a burrowing agent should be noted on
the shore; it will be noticed that its
general appearance varies much, accord-
ing as it is in action or at rest. It
protrudes from the anterior extremity
of the shell, and the united siphons
from the posterior. When the animal
is undisturbed these are protruded at
the surface, and have the usual func-
tions.
The two last Bivalves we shall con-
FIG. 82. —Razor -shell sider make their homes not in sand or
(Solen siliqua). /.foot; mu(j kut in rocks, into which they
at the other end the . , . ' . J
siphons (s) are visible, burrow deeply. Ihese are Saxicava
rugosa and the species of Pholas. The
first is abundant everywhere, wherever suitable rocks
occur. It is common in limestone, which is often literally
honeycombed by its burrows. The blocks are thus ren-
BIVALVES AND CUTTLES 285
dered less resistant to wave-action, and are torn off from
the solid mass of rock. They are then often utilised in
rockeries, and on the East Coast it is common to find these
built of such honeycombed stones still retaining the little
shells. In the living condition the animal is very common
on the shore, where its bright red siphons are to be seen
protruding from rock surfaces. When touched they eject
a forcible jet of water and then disappear. By breaking
the rock, specimens can be obtained without difficulty, the
shells though small being solid and not readily broken.
They are oval in shape and gape at the posterior end ; the
colour is white, and the shells generally without much
beauty. It seems unnecessary to describe the details, as
the bright red siphons and the habitat form very distinctive
characters.
Even more interesting are the species of Pholas, which
have singularly beautiful shells. One species, P. crispafa,
is exceedingly common in the Firth of Forth, where it
excavates the shale in all directions. Some of its charac-
ters have already been noticed in Chapter I., so we may
confine ourselves here to some details of the shell. As in
all species, this gapes widely both in front and behind; there
is no ligament nor teeth, but there is an accessory valve, or
dorsal shield, beside the hinge; the hinge-plate is reflected
over the beaks, and the shell is divided into nearly equal
parts by a broad oblique furrow. Of the two regions so
formed the anterior is furnished with about twenty rows
of overlapping prickles, supposed to be of great importance
in boring ; the posterior region is quite small. The whole
shell is pure white and very brittle, so that a little care is
necessary to obtain uninjured specimens. Another species,
P. Candida, also occurs in shale, but may be distinguished
by the absence of the furrow, the prickles covering the
whole surface except a space at each end.
We have now mentioned most of the Bivalves likely to
be found living between tide-marks. Of the Mollusca there
still remain the Cephalopoda, or Cuttles, specialised forms
in which the foot has grown up round the head and become
split into eight or ten sucker-bearing arms. Other character-
istic structures are the funnel, through which jets of water
can be ejected, thus producing motion, and the ink-bag,
286 LIFE BY THE SEASHORE.
whose contents produce a dark cloud in the water. The
cuttles are powerful animals and active swimmers; except
at the breeding season they are rare between tide-marks.
In the early months of the year a large form, Ommastrephes
todarus, is common on the beach after storms on the East
Coast, but this is due to the fact that at this time the
animals come shorewards to lay their eggs. The spawn,
both of this form and of Loligo vulgaris, is not uncommon.
The former consists of somewhat pear-shaped masses, each
containing many eggs embedded in jelly and fastened in
dense clusters to weed. In the latter case the eggs are
arranged in long tubes, which are similarly attached in
clusters to weed. The animals are, further, at times repre-
sented by their "pens," which are internal structures
corresponding to the "bone" of the squid (Sepia), and
probably to the last remnant of the shell which the early
cuttles possessed. The pens of Loligo and Ommastrephes
are horny structures, not unlike a quill pen, and reaching
a length of a foot or more.
In a living cuttle the beautiful changing tints should be
noticed, the arms and suckers, the jets of water which are
ejected from the funnel, and in natural conditions drive the
animal backwards, the fins fringing the body, and the large
eyes. A dead specimen will show the strong parrot beaks
within the mouth, the gills within the mantle-chamber,
and the ink-bag. The special characters of Ommastrephes
todarus are as follows : The fins are placed at the posterior
end of the body; the two long arms are nearly as long as
the body ; the eight short arms have two rows of suckers ;
the cornea, or transparent skin over the eye, has a central
hole, so that the sea-water gains access to the anterior
chamber of the eye. The animals reach a length of over
a foot. Between tide-marks in the South a pretty little
octopus, or form with eight arms, is at times to be found.
This is Eledone cirrosus, a very charming little creature.
On the shores of the English Channel the common octopus
(Octopus vulgaris) is at times abundant in the vicinity of
the shore.
BIVALVES AND CUTTLES.
287
KEY FOR IDENTIFICATION OF COMMON BIVALVES.
BIVALVES, or LAMELLIBRANCHS.
(1) Filibranchs, with filamentous or thread-like gills.
Shell of irregular ^
shape, lower valve V Surface scaly, without ribs Anomia ephippium.
with aperture . J
'Shell wedge - shaped, %
beaks terminal, colour I Mytilus edulis.
blue . . . J
Shell oblong, swollen in^
front, beaks anterior, \Modiola modiolus.
colour dark purple . J
Shell short and tumid, ^
££C±££S$! <" """
yellow . . . J
(2) Pseudo - lamellibranchs, gill -filaments only slightly attached
Shell equivalve, oval
or oblong, beaks
incurved, hinge"5
without teeth
together.
Shell suborbicular, inequi-
valve, marked with ribs,
beaks with distinct ears,
shell not gaping, brightly
coloured
Pecten
Lima
Ribs 20, surface with minute
scales — P. opercularis.
Ribs 14 to 16, surface with
radiating striae — P. maxi-
mus.
Ribs 40 to 60, prickly on
upper valve only — P.
>• pusio.
Shell like the above, "
gaping, colour white,
valves equal
Shell irregular, ineq ui valve, ^
upper valve flat and lower \ Ostrea
concave, teeth absent . J
(3) Eulamellibranchs, gills plate-like, the filaments firmly attached
together.
(a) Shell closed.
Shell oval, with distinct 1
epidermis and external I „
ligament, no pallial f °Wrina
sinus . . . . J
" Shell solid and opaque,
triangular — M. solida.
Similar, but smaller, more
convex, and with more
prominent beaks — M.
subtruncata.
/Shell oblique, gaping widely
' \ at both sides — L. Mans.
{Shell round in young, and
later becoming irregular
—0. edulis.
f Shell obliquely triangular,
-j swollen towards beaks —
v C. islandica.
Shell triangularly oval,
slightly striated, with
deep sinus, cartilage
internal
Maetra
Shell thin, glossy, with
brownish rays— M. stul-
torum.
288
LIFE BY THE SEASHORE.
Shell wedge - shaped, 'j
smooth glossy, with I D
external ligament and j
deep sinus . . . J
Shell compressed, rounded ^
in front, angular and j
slightly folded behind, V Tellina
ligament external, pro- j
minent . . . . J
Shell rounded, solid, with ^
concentric ribs and small V Venus
sinus . . . . J
Shell oblong, beaks an- ^
terior, margin smooth, 1- Tapes
sinus deep and rounded . '
Shell convex, triangular, •
with radiating ribs,
notched margin and
fluted interior. Beaks
prominent, incurved
(b) Shells gaping.
Shell oblong, valves un-
equal, left valve the
smaller, with large carti-
lage process . . . .
* Cardium
Mya
Shell oblong, two diverging \ T,lfrnr{n
cardinals in each valve . / Lutrana
Shell elongated, cylindrical, ) «,
margins parallel. .} Solen
Shell rhomboidal, wrinkled, j Saxicava
truncated . . .J
Shell white, opaque, with }
rows of prickles, acces- I
sory valves or shields j
present . . . .J
PJiolas
Margin strongly notched,
interior stained with
purple— D. vittatus.
/ Shell thin, glossy, semi-
\ transparent — T. tenuis.
f Shell triangular, inside
J margin notched, except
j at posterior side — V.
\ striatula.
{Shell solid and opaque,
marked by numerous
fine concentric bands —
T. pullasf.ra.
f Ribs 24 to 28, furrows nar-
\ row— C. edulc.
• Shell oblong, twice as long
as broad — M. arenaria.
Shell oval, abruptly trun-
cated behind — M. trun-
cata.
i Shell compressed, elliptical,
! brightly coloured — L.
[ elliptica.
/ Shell straight — S. siliqua.
\ Shell curved — S. cnsis.
f Shell small, about 1 inch
\ long— S. rugosa.
{Shells divided by furrow,
20 rows of prickles on
an terior side — P. crispata.
Shell not divided, 25 to 30
rows of prickles — P. Can-
dida.
NOTE ON DISTRIBUTION.
The Bivalves described in this chapter are, generally speaking, those
which may be expected to occur at all parts of our coast, so that little
can profitably be said as regards distribution. It is obvious that such
forms as the edible mussel and cockle cannot from their habits be
expected to occur, in any abundance at least, except where shallow,
BIVALVES AND CUTTLES. 289
estuarine waters are available. This is true to a less extent of other
sand- or mud -inhabiting forms which are naturally rare off rocky
coasts, and abundant on sandy beaches. But as sand and mud are
derived from rocks, it will be found that even neighbourhoods which
seem to be exclusively rocky exhibit somewhere stretches of sand
haunted by the common bivalves. A good example is the long stretch
of sand in the vicinity of Woolacombe, on the north coast of Devon,
where are to be found quantities of shells apparently absent from the
neighbouring rocky beaches. Similarly, the species of Pholas to be
found vary with the composition of the rocks, for many species stick
to one particular kind of rock. As to further detail, we may notice
that Lima Mans can only be expected between tide-marks in the
extreme South, and does not occur on the East Coast. On the other
hand, the brown Cyprina islandica is a Northern form, diminishing
in abundance as one passes southward. As regards the relative
abundance of the others, it should be noticed that in the vicinity of
fishing- villages the abundance of the shells of a particular species on
the beach depends largely on the fact that the species is used as bait.
The habits of the fishermen in regard to the bait used differ much at
different parts of the coast, so that a great accumulation of shells of
Cardium, Afactra, Mya, Cyprina, or Lutraria. at different parts is
not in itself a proof of the predominating abundance of the particular
mollusc.
CHAPTEE XV.
FISHES AND SEA-SQUIRTS.
Vertebrates and Invertebrates— Structure of a sea-squirt— Some com-
mon forms — Characters of fish — The saithe, or coal -fish — Sea-
scorpions, or bull-heads— Fishing- frog —The lump-sucker and its
eggs — Shanny, butter-fish, and blenny, their habits and structure
— The sticklebacks— Sand-launces— Flounders, plaice, and other
flat-fish.
ALL the animals we have hitherto studied have been
J\. without a backbone, or equivalent supporting-rod down
the back, have had a ventral instead of a dorsal nervous
system, and therefore, because of these and some other
reasons, all belong to the INVERTEBRATES. The VERTEBRATES,
or backboned animals, are most obviously represented on
the shore rocks by the fishes, of which not a few species
occur in the deeper pools. But there is in addition a group
of animals which, despite appearances, have some claim to
kinship with the great Vertebrate stock. These are the
sea-squirts, or Tunicates, which in larval life have a more
than superficial resemblance to tiny tadpoles. In adult life,
on the other hand, they diverge very widely indeed from
the Vertebrate ideal, being little more than sacs of jelly
with a tough, transparent coat.
Tunicates are common everywhere between tide-marks,
but the majority are small, so that we may have to hunt for
some time before finding a specimen of suitable size for a
first essay in dissection. In some shady nook, or under an
overhanging rock, you may find a flat, shapeless mass,
attached by one of the flat sides, and of a general greenish
tint. Peel it cautiously from the stone, disregarding the
sudden jet of water by which it shows resentment of the
290
FISHES AND SEA-SQUIRTS. 291
process, and place in a pool or dish. In a minute or two
the shapeless creature recovers sufficiently to stretch itself
out in the water, and show at one end two elongated tubes,
placed close together, of which the one shows eight, and the
other six, red pigment spots close to the fringed openings,
which are of yellowish colour. The creature has a soft,
greenish coat, sufficiently translucent to allow one to see
through it the distinct muscle bands of the underlying
body-wall. By means of these bands it can retract its
tubes or siphons, and contract the whole body suddenly on
an alarm, the test, or coat, being so soft as to offer no
hindrance to the process. In this respect, Giona intestinalis,
as this particular Tunicate is called, differs from most of
its allies, which have generally such stiff coats that their
activities are limited to that sudden ejection of water which
gives them their common name of sea-squirts. When not
alarmed, Giona lies passively at the bottom of the dish, and
it can be seen that a continuous flow of water passes in by
the one siphon and out by the other. With a little care
the internal anatomy can be made out, the Tunicates being
usually fascinating creatures to dissect. As an aid in the
process, a figure is given of a Tunicate from fairly deep
water, in which the coat and tissues are so transparent that
the internal anatomy can be made out without dissection.
Any Tunicate has outside the body the coat, or test (t),
made of a substance apparently identical with plant cellu-
lose, and varying greatly in thickness, colour, and con-
sistency. It can be very readily peeled off to show the
animal within. This has a thin muscular body-wall, usually
traversed by a network of slender muscular fibres, which in
Giona are collected in definite bands. The body has no
definite shape ; in Giona it is elongated, varying in length
from about two to five inches, but it is often rounded or
quadrilateral. In Giona the two apertures already noticed
are near together, and between them there is a little yellow
mass with a few radiating threads. This is all that repre-
sents the nervous system — so small and undeveloped that
one can have few scruples about hurting a sea-squirt's
feelings ! It is hardly probable that it can ever suffer from
" nerves."
Whatever the shape of the body in a Tunicate, tho
292
LIFE BY THE SEASHORE.
greater part of it is always filled up by the large branchial
sac (&?•), which usually runs from the mouth or upper
opening to the other extremity of the body. It is a
beautiful structure made up of bars crossing one another
at right angles, the rectangles so formed being filled up by
smaller bars with slits between them. The whole sac is
thus a sieve, but a sieve of beautiful and elaborate struc-
ture. To the exterior this sieve opens by the mouth (w),
and in life a continuous stream of water passes into it, then
through the slits into the space between branchial sac and
body-wall, and out by the lower (atrial, at) opening which
communicates with this space.
As the current passes through
the slits of the branchial sac
it washes the blood contained
in the bars, which are really
blood-vessels. The current is
thus primarily respiratory, but
it brings with it also the
minute particles on which the
sea-squirt feeds. These par-
ticles would be swept out
FIG. 83.— Corella parallelogramma, a with the Water of respiration
simple sea-squirt, so transparent •* fUPT,p W{,Q ^.-.f cnTno cr>nm'nl
that the internal organs can be « tnere Was not SOine Special
made out without dissection. For mechanism to retain them.
The mechanism is of somewhat
complex nature, and consists of two parts. To understand
their position we must first determine the orientation of the
body. We have noticed already the little nerve mass lying
between the apertures; now development shows that this
lies on the dorsal surface, and therefore that the short
region between the apertures corresponds to the back of a
fish, while the opposite edge is the equivalent of the ventral
or under surface of the fish. Along the ventral surface of
the branchial sac, then, lies a groove, the endostyle ; while
dorsally there is in Ciona a series of processes called
languets. The grooved endostyle secretes sticky mucus,
in which the food particles are entangled, and they are
then swept backwards apparently by the aid of the languets
into a slit-like opening at the posterior end of the branchial
sac. This opens into the stomach (st\ the stomach into a
FISHES AND SEA-SQUIRTS. 293
coiled intestine (in), this into a rectum (r), which runs
forward to end within the lip of the atrial opening.
This description may sound a little complicated, but with
the help of the diagram there should he no difficulty in
following it. Let us summarise the salient points. A sea-
squirt may be compared to what chemists call a two-necked
flask, or, as the more familiar object, to a narrow-mouthed
coffee-pot. Within the mouth of the coffee-pot let us
suspend a muslin bag, which may represent the branchial
sac. At the bottom of the muslin bag let us make a slit,
and fasten to the outer side of the slit a U-shaped tube,
so that one of the arms of the U reaches up to the spout,
and its base to the bottom of the jug. "We have then a
pretty close model of* a sea-squirt, but to complete the
resemblance we must suppose that the muslin is covered
with fine hairs, which continually bale the water through
its holes. Now pour in water containing coffee-grounds,
and we find that owing to the hairs (cilia) on the walls of
the bag, a current is created which drives the water through
the bag, and ultimately out by the spout. But owing to the
arrangement of groove and processes already mentioned the
coffee-grounds are, on the other hand, swept into the slit
and so into the U tube.
The muslin bag is the branchial sac, the mouth of the
coffee-pot corresponds to the mouth of the sea-squirt, the
U tube to the alimentary canal, the spout to the atrial
opening. The water, which is swept through the muslin
bag to ultimately gush out at the spout, is the water which
is used in respiration, for as it passes through the slits it
washes the blood contained on their walls, and so purifies
the blood. The coffee-grounds correspond to the food par-
ticles which are sifted out from the water, and pass from
branchial sac to stomach. Here they are digested, while
the indigestible residue passes into the rectum, and so to
the lip of the atrial opening. The matter is of course not
quite so simple as this analogy would suggest, especially in
that in most Tunicates the branchial sac is so large that it
has, as it were, squeezed the alimentary canal to one side,
and the relation of the parts becomes in consequence some-
what complicated. But the coffee-pot model indicates the
gist of the matter.
294 LIFE BY THE SEASHORE.
One interesting point is that, as the description shows,
the branchial sac has a double function, being both respira-
tory and nutritive, and that through it there constantly
flows a food- and oxygen-bearing current. This fact is
known and appreciated by a little water-flea, or Copepod
(Notodelphys ascidicola), which takes up its abode within
the branchial sac of various sea-squirts. It is hardly a
parasite, for it does not seem to injure the sea-squirt, but
seeks and obtains shelter, as well as abundant oxygen and
food from the incoming current. The habit might be de-
scribed as a first essay towards the adoption of the parasitic
mode of life, for it is probable enough that many parasites
began by merely seeking shelter. Such a method of life is
not peculiar to Copepods, for there are also fish which
similarly seek shelter within the cavities of sea-anemones
and sea-cucumbers, and the interesting case of the crab
and the mussel has been already noticed (p. 202). In all
such cases the cavity used for shelter must be one in which
there is an abundant supply of sea-water periodically re-
newed, by means of which the messmate can both breathe
and feed.
A considerable number of simple sea-squirts — as opposed
to those forms which produce colonies— are to be found on
the shore rocks, so that we can pick out one or two only.
Perhaps the commonest in most places is the " gooseberry "
sea-squirt (Styelopsis grossularia), to be found on rock
surfaces as a little bright red body, often so covered with
mud that nothing but the two bright red orifices is to be
seen. When touched these disappear in the surrounding
mud after squirting out a sudden jet of water. With a
little care it is possible to remove a few specimens without
injury, and make out something of the internal anatomy.
It will be found that the body is nearly spherical, and the
two apertures are placed close together, and are both four-
lobed. If with a pair of scissors you clip the animal in
two, you will see that the branchial sac has one deep fold
in it, as well as some other indistinct ones, and that the
inner surface of the body-wall has, on its surface, little
scattered masses ("polycarps"), which are the reproductive
organs, and are confined to the right side of the body-wall.
These points are worthy of notice, because they serve as
FISHES AND SEA-SQUIRTS.
295
FIG. 84.— Polycarpa rustica, a common
sea-squirt.
distinctions from Polycarpa rustica, another common red
Ascidian, which has four folds in the branchial sac at each
side, and has reproductive
organs on both sides of
the body-wall.
The " gooseberry " is
very common, and from
its tough, leathery coat it
is easy to cut into sec-
tions, which show the
anatomy clearly. By
taking a pair of scissors,
and clipping a few speci-
mens up at different angles
and in various planes, the
structure can be more
readily understood than
by even a very careful dissection of a soft form like dona.
As to the humanitarian aspect of the matter, it is difficult
to think that one can have more scruples than about slicing
a cabbage, but a tender conscience may be appeased by
immersing the specimens for a short time in methylated
spirit, and this will also assist the subsequent examination
by hardening the tissues.
Besides dona intestinalis, which we have already described,
several species of the genus Ascidiella are common on the
rocks. It is hardly possible to describe the specific characters
without going into details which are a little beyond our
reach, but we may note that a form called A. virginea is
very abundant in the Firth of Forth, where it grows
socially in dense masses attached to seaweed, or Polyzoa,
and is cast on the beach after every storm. It has a
delicate, transparent test, and the body-wall is often
beautifully necked with scarlet. If specimens are collected
immediately after a storm, they will be found to be still
alive, and the smallest of the bunch will show the beating
of the heart and the movements of the currents in a very
interesting way. Sea-squirts from deep water often have
very delicate tests, so that the internal structure shines
through clearly, but those found on the shore have usually
tough, resistant coats, which conceal the underlying organs.
296 LIFE BY THE SEASHORE.
In addition to the simple sea-squirts there are a great
number of colonial forms, in which the small individuals
are embedded in a common test, a number being usually
grouped round a common atrial opening. Very abundant
are the species of Botryllus, in which the colony spreads as
a great sheet of jelly over stones, the surface being studded
by little stars with a central hole. Each star is a cluster of
individuals grouped about the common atrial opening, while
the test of the simple Ascidian is represented by the sheet
of jelly in which the individuals are placed, and which
connects the clusters together. The colonies, for the most
part, avoid the light, and are to be found beneath stones,
and under overhanging rocks, but they are usually bright in
colour — purple, greenish, yellow, and red tints being common.
Along with Botryllus the species of Botrylloides also
occur, in which, instead of being in stars, the individuals
are arranged in long, double rows, which branch and
anastomose in a complicated fashion. The colonies form
their incrustations on the rocks just as Botryllus does,
and occur in similar localities. Where representatives of
these two genera occur freely, there will probably also be
representatives of other genera of compound Tunicates,
which in some cases, instead of being flat, form little
stalked masses of jelly. They can always be recognised as
Tunicates by the occurrence of the individuals, or zooids,
embedded in a common jelly, and in many cases it is easy
to pick out a zooid on a needle, and with a lens demonstrate
the existence of all the parts which we discovered in the
simple sea-squirt. But though the Tunicates — compound or
simple — are an interesting group, we must not linger over
them, for, generally speaking, they are too difficult as
regards their minute structure for most amateurs, and the
distinctions between even the genera rest, in most cases, on
minute points.
Finally, we come to the Fishes, of which we can name
only a few of those which haunt the rocks at low water.
Everyone who has watched fish in their natural surroundings
must have been struck with their singular beauty and grace;
cold, slimy, and shapeless as they seem when dead, in life
they are full of energy and vitality, as beautifully adapted
FISHES AND SEA-SQUIRTS. 297
to their surroundings as bird in air or mammal on land.
Into the details of structure we cannot go, but almost any
shore fish will serve to give you a general idea of the general
characters of a fish.
In the first place, with the exception of skate or dog-fish,
occasionally thrown up after storms, all our common fish
belong to the bony fish, or Teleosteans, which are geologically
recent animals, and display the fish-like characters in their
highest degree of development. But as the fish in its
highest development is, above all things, an animal adapted
for life in mid-ocean, for swift movement, we must expect
the forms available on the rocks to display the piscine
characters in a less typical form than their brethren of the
open sea. The fish which are always to be found in the
rock pools are those which are specially adapted for that
life, and which would be as helpless in the open sea as the
strong swimmers of that open sea would be if confined in
such pools by any untoward circumstance. Such shore fish,
therefore, display various peculiarities of form which
distinguish them from the more typical fish of the open sea,
but these peculiarities are usually of the kind known as
adaptive — that is to say, they occur in different fish not as
the result of inheritance from a common ancestor, but as an
adaptation to a common environment. Thus shore fishes
are often without scales, they often have an eel-like body
adapted for creeping through rock crevices, they may be
flattened to enable them to pass their lives on the bottom,
and so on.
Before proceeding to describe the peculiarities in detail,
let us look at a typical fish, choosing a member of the great
cod family, which includes many important food fishes. If
you idly row about in a boat in the summer time not far
from shore, or watch the streams of sea-water which ebb
and flow through the deep channels of the rocks, or gaze
down into the water from a pier or landing-stage, you are
certain at some time to see shoals of fish of a beautiful
greenish tint, which dart and wheel and turn in the water
like swallows in the air, showing gleams of glistening silver
at every movement. So abundant and so fearless are they
that even the simple artifice of a bent pin and a piece of
mussel will often produce several specimens, when employed
298 LIFE BY THE SEASHORE.
off the edge of the rocks with an incoming tide. The
humanitarian may protest against this, and exclaim that the
naturalist cannot admire without seeking to destroy, but the
fact remains that while you call these fish merely " fish " in
the indefinite sense, you will observe but little of their
habits; while if you possess yourself of a few specimens,
learn their name, and something of their characters, the
next time you see those shoals you will not only observe
much more than you did the first time, but your interest
will be greatly intensified, and your chances of seeing much
greater.
There need be no difficulty as to name, for these pretty
fish are saithe, or coal-fish (see Fig. 85), in the adult stage
Fio. 85.— Saithe, or coal-fish (Gadus wrens), to show typical fish-like shape,
di, d2, d'J, the three dorsal fins ; v, the ventral fin of right side ; p, the right
pectoral ; a1, a2, the two anal fins ; t, the equally lobed tail fin ; b, the rudi-
mentary barbule. Note also the lateral line, and the operculum (o) covering the
gills. After Day.
often sold to innocent housewives as cod, and in the young
stage known to all boys as poddlers, or by a dozen other
names beside. The adults grow to a length of two or three
feet or more, but the shoals found off the rocks in summer
time are usually the young, and are not more than a few
inches in length.
As in most fish, the body is spindle-shaped, tapering
behind so as to offer the least resistance to the water. It
ends in a tail fin which is equally lobed, so that every stroke
drives the animal straight through the water. This is a
point of some interest, for it is only modern fish which
possess tails of this kind. In the fish found as fossils in
the older rocks, as well as in the living dog-fish and skate,
FISHES AND SEA-SQUIRTS. 299
the tail fin is unequally lobed, the upper lobe being larger
than the lower. The result of this arrangement is that at
each stroke the body is inclined downwards, for the larger
lobe naturally gives greater impetus than the smaller. The
reason for this is that those fish which have unequally lobed
tails have their mouths on the under surface, and are usually
ground feeders, so that each stroke drives them nearer their
food, which they reach from above. Fishes with equally
lobed tails, on the other hand, have terminal mouths, are
swifter and more highly specialised. It should also be
noted that in fish the tail is the main organ of propulsion, a
fact which has resulted in various modifications of the body.
One of the most interesting of these is that the internal
organs have been shifted forwards, so as to leave the tail a
mere mass of solid muscle. It is a familiar fact that the
posterior opening of the food canal in a fish is far forward, and
that the body organs, heart, alimentary organs, reproductive
organs, etc., are, roughly speaking, crowded into the small
space in front of this opening. On the other hand, in most
vertebrates, such as frog, bird, mammal, the viscera extend
to the posterior end of the body, and the limbs are the great
means of propulsion. The student will find it of much
interest to compare the conditions in prawn or lobster with
those obtaining in a typical fish. In both cases the tail is
used as an organ of propulsion, and in both cases is in conse-
quence converted into an almost solid mass of muscle, which
renders both sought after by man as food. There are, how-
ever, many interesting differences in detail in the mechanism
in the two cases, and some even more interesting resem-
blances. Thus, in both cases the kidneys are shifted far
forward into the head region. It must not, of course, be
supposed that there is any relation between lobster and fish,
even if the former is legally a " fish," but the two have both
solved a mechanical problem after a similar fashion.
While swimming is effected in a fish by means of the
tail, the necessary steering is accomplished by means of
the fins. Of these there are two kinds — the paired fins
corresponding to the limbs of other vertebrates; and the
unpaired fins, which are to be found in the middle axis of
the body, and vary much in different fish. It is especially
interesting to note the position of the paired fins. As they
300 LIFE BY THE SEASHORE.
correspond to the fore and hind limbs of a terrestrial ver-
tebrate, one would naturally expect that the pectoral pair,
which are equivalent to the fore limbs, should lie in front
of the pelvic pair. This is the case in many fish, but in
the cod family they have been shunted forward till they
actually lie in front of the pectorals (see Fig. 85). This
shifting seems to be associated with the general moving
forwards of the organs of which we have already spoken.
As regards the unpaired fins we have in the saithe three
dorsals on the back, and two anals on the ventral surface
behind the anus, in addition to the tail fin of which we
have already spoken.
In regard to the other characters, the gills are of special
importance. In a living fish there will be noticed a flat
plate, or operculum, behind the mouth on either side, which
is constantly opening and shutting. It is easy to observe
that water is constantly entering by the open mouth, and
leaving by the opening at the side of the throat which is
disclosed when the operculum is raised. A more careful
examination will show that internally the sides of the
mouth are perforated (usually) by five clefts, bounded by
bony arches bearing red gill-filaments. Externally these
openings are not obvious, as they are covered by the
operculum, beneath whose posterior margin the water taken
in by the mouth escapes. As the water passes out it purifies
the blood contained in the gills, so that the mouth-cavity,
or pharynx, of the fish, like the pharynx of a Tunicate, has
a respiratory function, as well as its nutritive one. Other
important peculiarities are the teeth, not confined to the
margin of the jaws, but also found on the walls of the
mouth-cavity, and the "lateral line" — a series of superficial
sense-organs which run down the sides of the body, forming
a conspicuous black line in the haddock, a pale one in the
saithe. The scales should of course also be noticed, and
the flat, lidless eyes, so arranged as not to interfere with the
general curve of the body, and so offer no resistance to the
passage through the water. Into the anatomical details of
structure we cannot go, but the external form and the move-
ments are worth careful study, and your appreciation of the
graceful movements will probably increase as you learn more
of the mechanical adaptations which render them possible.
FISHES AND SEA-SQUIRTS. 301
Before leaving the saithe, we may note that the most
inexperienced housewife can distinguish it at a glance from
the cod, by the fact that while the latter has a long process,
or barbule, beneath the chin, the saithe has the merest trace
of one (see Fig. 85, b). There are other striking differences,
but this is the most readily observed, and is worth note,
because if cod is not a particularly attractive article of diet,
a full-grown saithe is very much less so.
Having gathered some general idea of the characters of
fishes from an examination of the saithe or one of its
relatives, such as the cod, haddock, or whiting, we may
glance at the characters of some of the common rock-
haunting forms.
Wherever the pools contain weed and stones one may be
sure of finding at least one species of Coitus, little fish
FIG. 86.- Sea-scorpion, or bullhead (Coitus scorpius). After Day.
belonging to the same family as the gurnet, and much feared
by children on account of their spines and a tradition that
they are capable of stinging. Two species are common, the
sea-scorpion (see Fig. 86) and the father-lasher, or lucky
proach, the former being usually from about six inches to a
foot in length, and the latter usually only a few inches,
though it has been found to attain a length of a foot or
more. In both cases the head is broad and large, curiously
disproportionate to the narrow, tapering body, and bears a
very wide mouth, always eager for food. The head is
flattened above, so that the eyes are in its upper surface
instead of the sides, as in the saithe, and the margin of this
flat head is furnished with spines borne on a plate called the
preoperculum. In addition to these, other spines ornament
other parts of the body, especially the head, but the skin is
otherwise soft and scaleless. The gill-cover seems at first
302 LIFE BY THE SEASHORE.
sight to be very different from that of the saithe, and is apt
to be a little puzzling. If the saithe be carefully examined,
it will be seen that the operculum consists of a flat hard
plate, fringed at the edge with a soft membrane supported
by some inconspicuous rays of cartilage, the whole lying
close to the lateral body-wall. In Coitus, on the other hand,
the soft membrane is greatly expanded, and is supported by
a number of long distinct rays, curved so as to leave a con-
siderable space between them and the underlying gills. If
you seize a living Coitus, you will find that it is capable of
greatly increasing this space by raising these rays and their
membrane (the branchiostegal or gill-cover membrane), so as
to greatly increase the width of the head. As the head
swells the spines are erected, so as to make the Coitus an
ugly mouthful. There can be no doubt that this must
protect the fish against attack, for there are not a few stories
of birds found choked by getting the distended head with
its sharp spines fixed in the throat. If you compare the
ugly "bullhead" with the saithe, you will notice at once
how much the misshapen head takes off from the graceful
fish shape, as it must also diminish the swiftness of motion,
but great swiftness is probably not necessary to a rock-
haunting form, and the shape fits it for a life among rocks
and weed.
As to the other characters, we may notice that the
pectoral fins are large and fan-like, accentuating the size of
the anterior region of the body, while the ventrals are small
and inconspicuous. There are two dorsals and one anal fin,
and the tail fin is simply rounded and not cleft. There is
no marked distinction in colour between the two forms, the
general tint in both cases being brown or greyish green,
prettily marked and banded with dark brown or black. In
the sea-scorpion the under surface is pale, or sometimes
yellow, with strong dark markings. There is no great diffi-
culty in distinguishing the two species. In Coitus scorpius,
the larger, the preoperculum bears two spines, the upper
and longer of which is less than the diameter of the eyes;
the first dorsal fin has nine to ten rays, the second thirteen
to fourteen, and the anal nine to thirteen. In Coitus bulalis
the preoperculum bears four spines, of which the uppermost
and longest is longer than the diameter of the eyes, and the
FISHES AND SEA-SQUIRTS. 303
fin rays number as follows: first dorsal, eight; second dorsal,
eleven to twelve; anal, nine. Both species often occur in
the same locality, are easily caught, and, in the case of small
specimens at least, live well in confinement. Very small
father-lashers can easily be kept alive in a shallow pie-dish,
provided they are regularly fed, for they are exceedingly
voracious. Almost any small marine animal is acceptable,
especially the young of other fishes, which are eagerly
snapped up. In consequence of their voracity, and the
ungraceful shape, the bullheads have come in for not a
little abuse at the hands of even naturalists, who should be
unprejudiced persons ; but, nevertheless, in life in their
natural environment, they certainly do not lack that adapta-
tion to their surroundings which is the first canon of
beauty, while their vivacity and activity make them most
interesting pets.
The next fish we shall consider haunts in life sandy
places, but is often cast up on the shore, and has such a
mass of fact and fancy interwoven with it that we cannot
pass it by. This is the fishing-frog, or "angler" (Lopliius
piscatorius), sometimes called the sea-devil. It grows to
a huge size (six to seven feet), and is then certainly ugly
enough, but very small specimens are fascinating little
creatures. The head is exceedingly broad and flattened,
the mouth being enormously wide and capacious. The
name is derived from the fact that the first dorsal fin is
represented by a series of spines, of which the first three
are detached and form the " fishing-lines." The first bears
a little glistening flap of skin which acts as a lure in the
following way. The angler partially buries itself in the
sand ; the filament, which lies close above the mouth, pro-
trudes from the sand, and its terminal plate, which can be
moved by an elaborate series of muscles, quivers in the
water. The result is that little fishes swim up, from curi-
osity or hope of food ; then the great jaws open and the
little fishes are seen no more. The stratagem is evidently
successful, for the anglers obtain an enormous number of
fishes, so many that in some places the fishermen open
them for the sake of the contained prey. The anglers
swim but slowly, so that they could not hope to overtake
their prey by chasing them. When found thrown up on
304 LIFE BY THE SEASHORE.
the beach the colours are striking enough, being dark above
and white below; but it is said that in aquaria the fish
show remarkable resemblance to the surroundings, and even
when not buried are very inconspicuous. In the anterior
regions especially, the sides of the body are furnished with
fringed filaments, which resemble fragments of weed, and
must assist the process of concealment.
Apart from the lure the angler has many striking peculiar-
ities of form, most of which are obviously adaptations to
the peculiar habit. Thus, while the pelvic fins are small
and short, the pectoral are strong and remarkably modified,
so that the fish can use them to progress over the bottom,
or to excavate cavities in which the body may be concealed.
The reason why the arm-like fins are used in creeping along
the bottom, instead of the same result being produced by
strokes of the tail as in most fish, is supposed to be that
the former produces a silent, or rather waveless mode of
progression, which is more in harmony with the habit of
stalking the prey than rapid motion accompanied by dis-
turbance of the water would be. The motion is greatly
assisted by the somewhat elaborate articulation of the fins,
which makes great freedom of movement possible. Again,
the great mouth is furnished with numerous incurved teeth,
which permit of very free entrance, but no exit. This is
not always an unalloyed advantage to the angler, however,
for it has been known to swallow such things as stone
sinkers, cork buoys, hooked fish, and even the ends of boat-
hooks or mops, and being unable to readily reject them
again has been ignominiously captured. But to the tales of
the power and feats of the angler there are verily no end,
for its habits have always aroused intense interest from the
time of Aristotle to the present day.
It is perhaps hardly necessary to describe in detail the
other peculiarities of structure, for the huge head, with its
dangling filaments, makes the animal easy to recognise. Its
interest is that it illustrates, to an even more striking
degree than the species of Coitus, how the typical fish-shape
may be lost as an adaptation to a special mode of life.
Another interesting fish, sometimes thrown up in hundreds
on the beach in spring, is Cyclopterus lumpus, the lump-
sucker, a curious unwieldy animal, interesting on account
FISHES AND SEA-SQUIKTS. 305
of its habits. The young may be found in abundance in
the rock pools in summer and autumn, but to get the adults
one must search in the early spring months. Then, in pools
through which a stream flows, you may often find a large
mass of bright pink eggs, adhering to stones or weeds.
Close beside it, often half uncovered at low tide, is the male
parent, who with great devotion watches the eggs until they
hatch. He is said to carry away the young with him after
hatching has taken place ; but I do not know how to re-
concile this statement with the fact that the young are
abundant in the rock pools. Of the devotion of the males,
however, there can be no doubt, for they may be watched
every spring, and by marking a specimen it is easy to show
that the watching lasts for at least several weeks. Un-
fortunately, as March and April, the months in which the
eggs are laid, are apt to be stormy months, the weeks of
watching are not infrequently prematurely cut short by the
death of the male. In both sexes there is a curious suctorial
disc on the under side, by means of which the animals can
attach themselves to any firm surface, but as they are feeble
swimmers they are unable to resist the action of the waves
when once torn from their attachment, and the males
especially, from their prolonged and dangerous proximity to
the shore, are peculiarly liable to destruction in high winds.
In regard to the special characters (see Fig. 7) the body
is short, thickened, and elevated, and marked by strong
lines of tubercles. Of these there is a prominent row along
the middle of the back, which, being elevated on a crest,
gives rise to the Scotch name of paddle-cock or cock-paidle
(the male), and three pairs of lateral rows, in addition to
numerous scattered processes. These tubercles, together with
the ventral sucker (formed of the ventral fins), make it im-
possible to confuse the fish with any other. The colours,
especially on the under surface, differ in the two sexes, for
this is orange-red in the breeding male and bluish black in
the female. Though its appearance is not appetising, readers
of The Antiquary will remember that in Jonathan Oldbuck's
time at least the " cock-paidle " was prized as food. It does
not appear to be now commonly used in this way, but those
cast on shore after the storms of spring are said to be some-
times carted away to be used as manure or for feeding pigs.
306 LIFE BY THE SEASHORE.
If the adults can hardly be described as graceful, the
young, on the other hand, are charming little creatures,
which are readily captured, live well in captivity, and make
delightful pets. They differ markedly from the adults in
appearance, being without tubercles, and exhibiting a singu-
larly close resemblance to tadpoles. This is especially the
case with specimens taken from dark-coloured pools, for
these have the dark tint of frog tadpoles. Specimens taken
from pools containing much bright weed, on the other hand,
are often a fine green or olive-green tint, with conspicuous
light streaks behind the eyes. They are active little crea-
tures, darting about the water much more rapidly than the
adults, but nevertheless they frequently attach themselves
by the sucker, and then have a curious habit of tucking the
tail round the large head. The result, when combined with
FIG. 87. — Common shanny (Blennius pholis). After Day.
the colour resemblance to the surroundings, is to render
them very inconspicuous, and it is interesting to watch a
pool with several of the little creatures darting about, and
notice how they disappear suddenly from view, to be found
again after careful search as apparently shapeless masses on
the weed. Another interesting peculiarity is the fact that
the tail fin is quite colourless, and therefore practically
invisible. In consequence the dark - coloured specimens
particularly seem to be sharply truncated in the posterior
region, which enhances the peculiarity of the appearance.
The next fish we shall consider is the shanny (Blennius
pholis, see Fig. 87), which may be described as a typical shore
fish, for it lives in shallow pools, lurking under stones and
weed, and is quite able to withstand the temporary disappear-
ance of the water. Indeed, in confinement it seems to greatly
prefer a situation where it can periodically leave the water
for a time. The colours are not very definite, the body
FISHES AND SEA-SQUIRTS. 307
being generally greenish, marked and blotched with black,
but the tints are so arranged as to correspond generally to
the lights and shadows of a rock pool, and show a very
considerable range of variation in harmony with changes in
the surroundings. Specimens may be found of six or more
inches in length, but a common size is three or four inches.
Scales are absent as in most shore fishes, and the mouth is
furnished with strong sharp teeth, quite capable of giving an
incautious finger a sharp pinch ; their function is to nip off
the shell-fish, acorn-shells, and so forth on which the
shanny feeds. In the related wolf-fish (AnarrMchas lupus),
which is an inhabitant of deeper water, but is often cast
ashore during storms, the teeth are exceedingly strong, and
can inflict an ugly wound, but the little blenny can cause no
apprehension in the case of a discreet person.
There is little difficulty in recognising so common a fish
as the shanny, but the following points may be noticed.
The body is compressed and somewhat elongated, and slimy
to the touch ; the cleft of the mouth is narrow and strongly
toothed, and the anterior of the two nasal pits at each side
is furnished with four or five small filaments. The fins are
especially characteristic, for instead of two dorsals there is
one long fin with a very distinct notch near its middle.
The pectorals are large and expanded, while the ventrals
are represented by two rays only; there is a long anal
which, like the dorsal, does not meet the caudal. Nearly
all these points are shown in the figure. A cunning and
comical little fish, the shanny is well worth careful study.
It has a habit of poking its head out of the water or the
crevice in which it is lying, and as the lips are thick and
well marked, it has then a ludicrous resemblance to a
sulky, pouting schoolboy. The pectoral fins are extensively
used in clambering about the rocks, the small ventrals also
assisting in this process. It lives well in confinement if
kept in shallow water and allowed an opportunity of
leaving the water at times, and is a very favourable subject
for the demonstration of colour change, as the tints vary
with those of the surroundings.
Another very common fish belonging to the same family as
the shanny is the gunnel, or butter-fish (Gentronotus gunnellus),
which is, however, in regard to habits at least, a less interesting
308 LIFE BY THE SEASHORE.
creature. It has a peculiarly elongated and compressed form,
is exceedingly slimy to the touch, so that though it is not
particularly difficult to catch it is very difficult to retain when
caught, slipping through the fingers like the proverbial eel.
It is most commonly found under stones or weed, often
quite out of the water, and when uncovered regains the
water by very vigorous contractions of the body. Apart
from the eel-like shape, it is readily recognised by a row of
dark spots, usually about twelve in number, which run
down the back on or close to the long uniform dorsal fin.
Otherwise the colouring is not striking. The pectoral fins
are not large and the ventrals very small, so that there is
little to break the uniformity of the long, lank body. The
anal fin is present along about the posterior half of the
body. In water the gunnel swims easily and rapidly, but
at low tide it is most frequently found under stones in the
quiescent state. About six or seven inches is a common
FIG. 88.— Gunnel (Centronotus gunnellus). After Day.
length, though larger specimens may be found, In early
summer one sometimes finds the young, curious white
creatures, with the heart clearly visible through the trans-
parent body-wall.
Allied both to the gunnel and the shanny is the vivi-
parous blenny, a comparatively large fish — it reaches a length
of two feet — common between tide-marks. It is a little
apt to be confused with the shanny, although when the two
are put together the differences are well marked. As its
name indicates, the viviparous blenny (Zoarces viviparus)
gives birth to living young, instead of laying eggs, as the vast
majority of fishes do. The young are from one to one and a
half inches in length at birth, and are to be found in various
stages of growth at all seasons in the rock pools, while the
full-grown adults only occur there at times. Perhaps the
most obvious distinction from either the shanny or the
gunnel lies in the fact that the viviparous blenny has no
apparent tail fin, the dorsal and anal fins merely meeting at
FISHES AND SEA-SQUIRTS. 309
the tapering posterior end of the body. The tails of the
three forms are indeed worth careful comparison, for in the
shanny the tail fin is distinctly separated from the anal and
dorsal, in the gunnel these meet it, but the tail fin persists
unaltered ; a similar arrangement obtains in the young vivi-
parous blenny, but as it grows older the tail fin disappears,
leaving only the united dorsal and anal. In general shape
the viviparous blenny may almost be said to be intermediate
between the shanny and the gunnel, for it is less elongated
and compressed than the latter, and more so than the former.
The long dorsal fin, instead of having a notch as in the
shanny, has near the tail a region containing ten spines,
whose height is considerably less than that of the soft rays
which support the rest of the fin. The result is to produce
what is known as a "depressed" region in the fin, a very
characteristic peculiarity. The anal fin is longer than in
the gunnel, for it extends through about three-fifths of the
body-length.
After the blennies we come to that most interesting
family, the sticklebacks, which are more or less familiar
to most people. In rock pools the commonest form is the
fifteen-spined stickleback (Gasterosteus spinachia), which
reaches a length of six or seven inches. In spring and
early summer the pools often swarm with the young, which
are most charming little creatures, and hardy in confinement,
while a lucky naturalist may now and again find the nests,
with the fierce father watching over the precious contents.
The nests are, however, most usually in spots sheltered from
violent wave-action.
There is no difficulty in recognising a specimen of the
fifteen-spined stickleback, for the long snout and small
mouth, the fifteen spines which represent the first dorsal
fin, the row of strong plates at each side of the body, and
the expanded fan-like anal, second dorsal and caudal fins,
are all eminently characteristic structures. There is also
something so peculiar about the way in which the little fish
roots about with its long snout, and directs its tapering
body in and out of the rock crevices, that one recognises it
at once as different from the bullheads or blennies — the
other common rock fishes. Like the other sticklebacks, it
is an active and pugnacious little fish, though its habits
310 LIFE BY THE SEASHORE.
have received less attention than the three-spined form. It
does not appear to extend into fresh water, and is most
abundant in pools containing much weed and stones, but
I have also found it in sandy places. It will be noted that
it is the male which makes the nest, and watches over the
eggs, just as it is the male lump-sucker which watches over
the eggs. It is true generally of bony fishes that where
there is any evidence of parental care, it is the male parent
which takes on this duty. The same is true of Amphibians
— frogs, toads, newts, and their allies — while among
mammals the care of the young usually falls to the mother
alone.
In addition to the fifteen-spined stickleblack, the three-
spined form (Gasterosteus acideatus] does occasionally occur
in rock pools, though typically a fresh-water form. It
occurs not infrequently in brackish pools just at high-tide
mark, especially those in the vicinity of fresh-water streams.
In such pools, also, the nests may at times be found, but
they are too well known to need further description. The
three-spined stickleback is hardly so pretty a fish as the
fifteen-spined form, for it has a more typical fish-like
shape, without the long snout of the fifteen-spined form,
and with three, or occasionally three or four, spines on the
back instead of fifteen. Usually the fish are not more than
two to three inches in length, but they are excessively
pugnacious, not only fighting furiously with each other, but
never hesitating to attack fish much larger than themselves.
In such combats the strong spines, which they can use very
effectively, form very powerful weapons, while the strong
plates at the sides of the body form an efficient defence
against the attacks of other fish. In the breeding season
the males especially are of a brilliant orange-red beneath,
the colours both there and in the other parts of the body
varying in intensity according to the emotions of the fish,
being brightest after victory, palest after defeat, or when
the fish are under the influence of alarm. The tolerance of
either fresh or salt water is remarkable, especially as there
is no regular seasonal alternation between the two as in
salmon or some other fish. The extraordinary variability
must be associated with the power of changing the environ-
ment ; but while certain varieties seem to be better adapted
FISHES AND SEA-SQUIRTS. 311
to life in fresh water and others to life in the sea, the
capacity for change prevents the fixation of these varieties
as new species.
Of the large cod family we have already described one
member, and cannot devote more space to it or the related
haddock, whiting, cod, pollack, etc., most of which, as strong
swimmers, are more or less outside our range, though many
of them may be caught off the margin of the rocks.
Leaving them we may pass on to the sand-launces, or sand-
eels, which may be found in immense numbers near the
mouths of tidal rivers, in shallow water over a sandy bottom,
or by digging in the sand. Beautiful silvery creatures they
are, darting like shadows through the water, or burying
themselves with swift movements in the sand. Like the
young saithe, which swim in similar shoals, they are eagerly
attacked by sea-gulls, as well as by predaceous fish and
porpoises. On the calm summer days when the water is
so still that thistle-down, blown from the neighbouring
dunes, floats on its surface, and so clear that the bottom
seems within the reach of the hand, — on such days one
often sees flocks of screaming sea-gulls circling over dis-
coloured patches in the water, and ever and again darting
downwards to emerge with a silvery fish from the dense
shoals in the water. In the same way the gulls collect
about the river mouth as the tide ebbs, and seize the little
fish as they swim in the shallows. That this fate may not
overtake all, nature has furnished them with a protruding
lower jaw, which forms an efficient shovel, by means of
which the little fish may bury themselves deeply in the
sand. In some places the sand-eels are caught in large
numbers for bait and food by raking with hooks or rakes
the loose sand in which they live ; sometimes they are
merely dug for like sand-worms, but, as all boys know, they
may also be caught in a fine shrimping-net, or even by hook
and line.
There are two common sand-eels, the greater (Ammodytes
lanceolatus) and the lesser (A. tobianus, see Fig. 2), the
latter being perhaps the commoner of the two. A little
care is required to distinguish the two at first, but once
the differences have been accurately noted the task becomes
easy. As to size, the lesser sand-eel is usually only three
312 LIFE BY THE SEASHORE.
to four inches in length, the greater about six to seven
inches; but the former may reach seven inches, the latter
twelve to thirteen or more. In both cases the colours are
similar, being greenish above with broad lateral silvery
bands and a pale under surface, but the silvery gleam is
more pronounced in the smaller fish. Further, the latter
in proportion to its length is more slender than the larger
form, and tapers more rapidly in the anterior region. When
once appreciated this is the point most useful in distinguish-
ing the two, but till this can be done the distinction may be
very readily made in the following way. Draw an imaginary
vertical line from the anterior extremity of the dorsal fin to
the ventral surface ; in the lesser sand-eel this line will cross
the backwardly-directed pectoral fin, which is elongated and
pointed; in the greater sand-eel the line passes behind the
pectoral fin, which is short and rounded. In both species
note that there is only one dorsal and one anal fin, that
ventrals are absent, the scales minute, and the whole form
such as to render the action of burrowing rapid and easy.
The active agent in the process, as already noted, is the pro-
truding lower jaw, which is proportionately somewhat longer
in the greater than in the lesser sand-eel.
This short list includes most of the fish common in the
rock pools on the North-east Coast, but to the list may be
added the flounder, as an example of the exceedingly inter-
esting family of flat-fish, which includes in the turbot, brill,
plaice, sole, and others, some of our most esteemed food-
fishes. Young flounders are usually common in the rock
pools, and their many peculiarities of structure render them
worthy of careful study. As is obvious from their shape
they are ground forms, adapted for life on the bottom. In
this respect they resemble the skate and the fishing-frog, but
differ from both in the way in which the adaptation is
produced. In fishing-frog and skate the surface upon which
the animals rest is the under surface — a condition which
one would regard as the natural one; but in the flat-fish it is
one of the sides. In other words, the fish are laterally
compressed — squeezed, as it were, until the upper and lower
surfaces have become sharp edges. Note the results of this.
The pectoral fins in an ordinary fish lie at the sides of the
body, therefore in the flounder we find one on the upper
FISHES AND SEA-SQUIRTS. 313
coloured surface and one on the lower white surface; the
pelvic fins in an ordinary fish lie on the ventral (under)
surface of the body, therefore in the flounder we find them
both close together on that sharp edge which structurally,
though not actually, is the under surface of the fish. So
far all is relatively simple, but one naturally asks, What of
the eyes'? It is obvious that if they were to occupy the
normal position we should get one on the upper pigmented
surface, and one on the lower colourless surface, where,
owing to the ground habitat, it would be useless. In point
of fact, both eyes occur on the surface which is normally
uppermost, but this is accomplished by one of the most
remarkable phenomena in the development of fishes, the
gradual migration of the originally lower eye to the pig-
mented surface. The migration occurs during the early life
of the flounder, when the bones of the head are soft, and
results in an extraordinary distortion of the skull. Skulls
of some of the flat-fish may often be found on the shore,
and should be studied with special reference to the position
of the orbits. Similarly, while the young flounder has
pigment on both surfaces, later the under surface (left side)
becomes colourless, and the pigment is concentrated on the
upper surface (right side).
In some ways one of the most interesting points about
the flat-fish is the approach they make to a new type of
symmetry. It is obvious that fish, like so many animals,
are bilaterally symmetrical — that is, the two sides are similar
to each other — mirror images of one another. But in flat-
fish this similarity is no longer obvious, and the animals
tend to take on a type of symmetry in which the ventral
and dorsal surfaces resemble one another. Thus while in
most fish the ventral fin differs in appearance from the
dorsal, in the flat-fish it tends to be closely similar. Space
does not, however, permit of a detailed account of the
peculiarities of the flat-fish, or a discussion of the many
interesting points connected with them, and the disputes
to which they have given rise.
Small flounders are common in sandy pools, especially
about the mouths of rivers. They may be distinguished
from young plaice by the fact that the scales are rudimentary,
and that there is a row of tubercles at the bases of the
314 LIFE BY THE SEASHORE.
dorsal and ventral fins. The colour of the upper surface is
remarkably like that of the sand and mud in which the fish
live, whereas in the plaice it is blotched with orange spots
on a brown ground; but the most obvious distinction
between the young lies in the fact that the plaice has
well-developed scales and the flounder only rudimentary
ones. As is well known, the flounder usually lies buried
in the sand, with only the mouth and protruding eyes
exposed. It is very voracious and will eat almost any kind
of animal food. Under the name of "flatties" flounders
are often captured by boys, either by spearing or by the
more primitive method of covering them with the bare feet
as they lie in the shallow sandy water.
There are a considerable number of flounder-like forms,
all members of the genus Pleuronectes, which are apt to be
confused in common parlance; the name "dab" in itself and
its compounds being loosely applied to several species. It
is well, therefore, to expend a few pence in obtaining good-
sized specimens of the flounder (P. flesus), the plaice
(P. platessa), and the true dab (P. limanda\ so as to learn
once for all the notable distinctions between them. After-
wards the recognition of the young will be found easy
enough.
FISHES AND SEA-SQUIRTS.
315
KEY FOR IDENTIFICATION OF COMMON
SHORE FISHES.
Teleosteans (bony fish, with terminal mouths and equally lobcd or
rounded tails).
(1) Some of the fins are at least partially supported by spines.
.Head spines two,
shorterthan breadth
of eye — (7. scorpius.
Head spines four, one
longer than breadth
of eye — C. bubalis.
Lophius piscatorius, fish-
ing-frog.
§ fTwo to four dorsal
spines — G. aculea-
£ j tus.
•~ 1 Fifteen dorsal spines
\ — G. spinachia.
:No tentacle above
the eye — B. pho-
lis.
fNine to thirteen
JJ black spots on
|j back — (7. gunnel-
l lus.
t f Dorsal fin, with de-
S \ pressed area near
| ~\ end — Z. vivi-
5 \ parus.
Body with rows \Cyclopterus lumpus, the
of tubercles . j lump-sucker.
(a) Two dorsal fins,
Head broad and
the first with
weak spines.
. 8
6 T2
03 '-£ 1
depressed, six
rays in gill-
Head armed
^ro
cover mem-
with spines
O
, brane .
(6) First dorsal"
represented by
isolated tenta-
cles, or spines.
Pectoral fins
jointed . .^
Fam.
Pediculati.
Head very large, \
first tentacle
with silvery
lure, two >
others pre- \
sent, mouth J
very wide .'
- /^Ventral fins, if
(c) First dorsal1
represented by
spines, body
compressed . j
1
l!
N
present, con-
sist of one
spine and one
ray, placed far
back (abdo-
& \ minal) .
f Single dorsal,^
divided into
anterior spin-
ous and pos- V
terior soft
(d) Dorsals occu-^
pying nearly the
whole length of
the back, body
elongated and
cylindrical .J
Fam.
Blennidse.
region ; tail \
fin present .'
Single dorsal, 1
s p i n o u s !
throughout; j
tail fin present]
Single dorsal,"!
no tail fin, \
anal and dor- j
I sal meeting . J
(e) First dorsal ^j .A ^
represented by I Q ^
crest, ventral j S 'o
sucker . . J ^ °
316
LIFE BY THE SEASHORE.
(2) Fins all with soft rays.
A. Head symmetrical.
(a) One 'to three
dorsal fins, ven-
tral fins beneath
throat, body
elongated .
(b) Single dorsal
occupying most
of back,ventrals
rudimentary or
absent, single
anal
Three dorsal-
fins, two anal s,
ventrals with
six rays
No ventral fins,"
lower jaw
long, anus far
back
B. Head unsymmetrical.
Flat-fish with both"!
eyes on one sur-
face, one long |
dorsal fin and i
a similar long
anal . .J
Fam.
Pleuronectidae.
Eyes on right^ J
side, dorsal fin 1 ]|
begins above j- § -
its eyes, two |
pectoral fins . J ^
Barbule rudimentary,
lower jaw longer
than upper, teeth
. uniform — G. virens.
-Pectoral fin long and
pointed — A. tobi-
anus.
Pectoral fin short and
rounded — A. lanceo-
latus.
Teeth lanceolate and
compressed, lateral
line nearly straight,
scales present — P.
platessa.
Teeth conical, lateral
line curved, plates
at base of fin -rays,
' no scales — P. flcsus.
NOTE ON DISTRIBUTION.
The fishes and sea-squirts described in this chapter are for the most
part those which are widely distributed round British coasts, though
in regard to fishes especially other species will be found to be common
in pools on the Western coast. The curious lump-sucker is commoner
on Scotch than on English coasts.
CHAPTEE XVI.
THE DISTRIBUTION AND RELATIONS OF SHORE
ANIMALS.
What does ''littoral" mean? — Characters of the littoral fauna — The
two other marine faunas — Subdivisions of the littoral zone — Dis-
tribution of British forms— The geographical regions— Origin of
littoral animals — Evidence for and against a pelagic origin —
Difficulties of a final decision — Relations of littoral to terrestrial
and fresh-water forms — Conclusion.
WE have now completed our systematic survey of the
common animals of the shore, and as we began with a
preliminary study of the conditions of shore life, so it is
fitting that we should, in conclusion, return to the consider-
ation of some general points connected with the littoral
fauna. In the first place, we have not as yet strictly defined
the meaning of the word " shore," but have used it loosely as
meaning the area between tide-marks. It is, however, fairly
obvious that this area is not sharply marked off from the
area just beyond low-tide mark. Very little experience in
shore collecting shows that animals which in one area may
be found freely on the shore rocks, in another region can
only be found after storms, and thus obviously occupy
deeper water. We have noticed this with regard to Alcy-
onium and the beautiful plumose anemone (Actinoloba
dianthus), but it is true also of a great number of other
forms, and has in several cases given rise to active contro-
versies. Some particular authority gives water of a certain
depth for some animal, and this is quoted by others as a
final statement, and yet it is quite possible that in other
localities the same animal may occur in very different
317
318 LIFE BY THE SEASHORE.
depths. Indeed, it is well known that certain Echinoderms,
for instance, have a very wide range in depth. Generally,
we may say that in most cases depth of water does not in
itself determine distribution, taking depth in this case as
including only those comparatively trifling variations which
occur in the vicinity of the shore, and are to be measured in
unit fathoms. It may thus be asked, Is there really such a
thing as littoral fauna at all, or do the familiar forms of
the coast go down into the great depths 1 Before we answer
this question, suppose we in imagination begin a series of
dredgings off a rich coast, beginning operations quite near
the shore in water of eight to ten fathoms, and sailing straight
outwards. In our first hauls it is probable that we would
get no form which was not already more or less familiar on
the rocks. We would miss such shallow-water animals as
the periwinkles and the shore crab, but we should probably
get plenty of sea-urchins and starfish, various spider-crabs,
hermit-crabs, Galathea and swimming-crabs, sea-firs, and so
on, all animals which we know already on the rocks, though
the species might be different. As we progressed outwards
not a few familiar forms would disappear, and others would
appear, but it is nevertheless true that we might take a
series of dredgings from the East Coast of Scotland across
the North Sea to the coast of Denmark, without ever
losing sight of some characteristic littoral forms, especially
certain Echinoderms. Further, in the course of our journey
we should nowhere find a depth exceeding fifty fathoms.
From these observations then we should conclude that the
littoral fauna must at least extend down to fifty fathoms,
though, except some of the Echinoderms, there are not very
many species which can live equally well in water of a few
fathoms depth and that of fifty or more.
If, on the other hand, we took our series of dredgings
on the West Coast of Scotland, we should find somewhat
different conditions. In the first place we should get into
deep water more quickly, and in our journey westward
would soon cross the fifty-fathom line. If we went onwards
we should find the percentage of familiar species and
familiar genera decreasing as we approached the hundred-
fathom line. After this the sea-bottom slopes somewhat
rapidly down to the great depths, to be measured in
DISTRIBUTION OF SHORE ANIMALS.
319
thousands of fathoms, whose inhabitants are usually peculiarly
modified for their life in the " utter dark." Generally then
we may say that the British Isles stand on a plateau
bounded, except at the West, by the fifty-fathom line.
The animals which live at the sea-bottom within this area —
or up to the hundred-fathom line on the West — constitute
the littoral fauna. This
littoral fauna is con-
trasted with the pelagic
fauna, which includes
those animals adapted
not for life on the sea-
bottom, but for life in
the open water, and with
the abyssal fauna, which
includes the animals
adapted for life on the
sea - bottom at great
depths. Later, we shall
have something to say
as to the relations of
these three faunas ; mean-
time we may note that
the littoral zoophytes
bud off pelagic medu-
soids, and that most of
the littoral animals
(Echinoderms, Crus-
tacea, Mollusca, etc.) have
pelagic larvae. Further,
the fact that the starfish FIG.
Henricia sanguinolenta,
common between tide-
marks, is to be found also at a depth of over 1,000 fathoms,
shows that the littoral and abyssal faunas are not sharply
marked off from one another.
We have thus defined the littoral fauna as including,
roughly speaking, all the animals which are adapted for
life on the sea-bottom in water of under 100 fathoms in
depth. In many parts of our area, however, as a bathy-
inetrical map will at once show, the greatest available depth
. — "Herring-bone coralline," or Halecium
halecinum. After Hincks. A common littoral
zoophyte.
320 LIFE BY THE SEASHORE.
within a reasonable distance from the shore is very much
less than 100 fathoms, and usually not more than thirty to
fifty fathoms, so that in most places we may say that our
littoral fauna includes the animals found on the bottom
in all depths from 0-30 fathoms. Even this is a con-
siderable range of depth, and it is natural to ask whether
it is not possible to divide the littoral area into zones ac-
cording to the depth. Such attempts have frequently
been made, but we have already emphasised the fact that
depth is only one of the factors determining distribution,
and perhaps not the most important factor. Other factors
are wave-action, temperature, food, the salinity and clear-
ness of the water, the nature of the bottom, and so on.
We shall therefore consider certain areas of the littoral
region as determined by the nature of the bottom rather
than by depth alone. Thus the bottom may be rocky, a
condition often well exemplified between tide-marks, where
the ebb and flow of the tide and the action of the at-
mosphere split and fissure the rock surfaces, hollowing
them out in a way which renders them eminently suitable
as haunts for many animals. The rock surfaces are over-
grown with luxuriant weeds, green, brown, and red.
Near low-tide mark one sees the great blades of oar-weed
(Laminaria) marking the shoreward limit of the Lamin-
arian zone, which extends downward to a depth of fifteen
fathoms. On rocky coasts one finds that the dominant
forms from high-tide mark to the margin of the Lamin-
arian zone are limpets, periwinkles, tops, dog-whelks, the
shore crab, many Amphipods and other small Crustacea, the
hardy smooth anemones, acorn-shells, the common starfish,
and other hardy forms. In the Laminarian zone itself an
enormous number of interesting and beautiful creatures
occur — sea-urchins, starfish, brittle-stars, many anemones,
the delicately tinted sea-slugs, spider-crabs, the edible crab,
prawns and Mysids, Galathea and porcelain -crabs, many
Annelids, and so on. Again, if the bottom be of sand or
mud, instead of rocks, the great oar-weeds are replaced by
sea-meadows of Zostera, among whose grassy blades the
sea-hare, the cuttles, and many other interesting Molluscs
lurk. By digging in the sand or mud one gets all those
interesting creatures we have already mentioned — burrow-
DISTRIBUTION OF SHORE ANIMALS. 321
ing anemones, such as Peacliia ; burrowing Annelids, such^
as Arenicola, Nerine, Glycera ; burrowing Echinoderms,
such as heart-urchins and Synapta ; burrowing Molluscs,
such as Solen, Mya, Lutraria, and so on. About the fifteen-
fathom line one comes to beds of clams, among which many
kinds of animals are to be found. Beyond this depth the
large seaweeds rapidly disappear, and the sea-bottom usually
consists of shell-gravel, sand, or mud, each region having
its peculiar fauna.
If, as we have supposed throughout this book, your
observations are limited to those animals which can be
obtained without a dredge, the regions which concern you
are the rocks between high- and low- tide marks, the Lami-
narian zone, whose margin is accessible at low spring tides,
and the sand or mud flats to be found especially near the
mouths of rivers. We have named above the commonest
inhabitants of these regions, but if we study this fauna in
detail in various parts of the coast we shall find enormous
variation. On parts of the East Coast the spider-crab
Hyas araneus is extraordinarily common, on the West
it is comparatively rare. In the pools on the Devonshire
coast a pretty little prawn, Hippolyte cranchii, is very
abundant, but it does not occur on the East. Throughout
our study of the common animals we have constantly
encountered similar facts, and frequently emphasised the
differences between the fauna of the North and East and
that of the South and West. Those who have interested
themselves in the distribution of British plants know that
somewhat similar conditions prevail with regard to them,
many species being found on the West which are absent
from the East. In both cases this may be in part ascribed
to the difference of climate, the Gulf Stream making this
much milder on the West Coast. In both cases, however,
the differences cannot be wholly ascribed to differences of
temperature. It is not very easy to divide the British area
into geographical regions according to the distribution of
the marine animals, but the following divisions at least
serve to illustrate the problems involved. The German
naturalist Michaelsen divides the European seas into three
provinces: (1) the Arctic, including the seas north of a
line drawn from the north corner of Iceland to the Lofoten
322 LIFE BY THE SEASHORE.
Islands on the coast of Norway ; (2) the Boreal, including
the seas bounded on the north by the line just given, and
on the south by a line drawn above the South Coast of
England ; (3) the Lusitanian, including the English Channel,
the Bay of Biscay, the coasts of Spain, and the Mediter-
ranean. Thus, except the South Coast, the whole British
area is within the Boreal region; but a map of the ocean
currents will show that certain of these sweep our western
shores, and crossing by the Shetland Isles sweep north-
wards along the coasts of Scandinavia. There is thus a
constant tendency for the Lusitanian types to travel up
along the West Coast, and such types may occur in the
far North in the Shetland Islands, and again on the coast
of Norway, while totally failing to establish themselves
on the East Coast. Again, as there is no sharp line of
demarcation between Arctic and Boreal regions, the Arctic
forms tend to spread southwards, and usually find it easier to
gain a foothold in the colder Eastern waters than in those
of the Western coast. Thus, except in the extreme South,
our marine fauna is generally of the Boreal type, but on
the West there is a strong admixture of Lusitanian types,
and on the East, especially the North-east, a strong admix-
ture of Arctic types. Especially curious are the conditions
in the Shetland Islands, where Arctic and Lusitanian forms
intermix.
Further, as our whole area is small and the con-
ditions fairly uniform, a dominant and successful species,
whatever its original home, is likely to occur in varying
numbers in all parts of our area. Thus the Norway lobster
(Neplirops norvegicus), a typical Northern form, which is
sufficiently abundant in the Firth of Forth to be the object
of an important fishery, does also occur, though not in such
abundance, off the South and West Coasts. The common
hermit-crab of the Boreal region is Pagurus bernhardus, and
of the Lusitanian P. prideauxii ; but on the West Coast the
two occur together in almost equal abundance. Similarly
the Stenorliynchus of the Lusitanian region is S. longirostris,
of the Boreal S. phalangium ; but in the Firth of Clyde the
two occur in almost equal numbers. Perhaps the prettiest
example of this overlapping process, however, is the dis-
tribution of the common starfishes. The common starfish,
DISTRIBUTION OP SHORE ANIMALS. 323
Asterias rulens, is the Boreal form, and is replaced in the
Lusitanian region by the spiny A. glacialis. The latter
species is totally absent on the East Coast of England
and Scotland, where A. rubens is abundant, often extra-
ordinarily abundant. On the West Coast of Scotland
both species occur, but A. glacialis is not very common.
In the South-west of England both species are abundant,
but east of Plymouth A. glacialis disappears. In this
case the Lusitanian form seems to find it difficult to
oust the Boreal species even in the warm waters of the
West. The two forms show no very obvious differences
of diet.
It is not possible to discuss in detail the distribution of
British marine animals, but we may say generally that a
form which occurs all round our coasts is probably a Boreal
form; one which is found only on the South and West
Coasts probably Lusitanian ; one confined to the North and
North-east probably Arctic. The study of distribution is
of great interest, and it is not necessary to travel over
wide areas to study it, for the differences between adjacent
areas are of as much interest as those between the ex-
treme North and extreme South, and illustrate the same
problems.
The more attention you devote to problems of distribu-
tion, the more will you become impressed with the fact
which we have constantly endeavoured to emphasise, that
the shore is the region characterised essentially by its great
variability. If you study one area for a succession of years
you will notice how currents change, how deposits brought
down by rivers vary in character and distribution. Closer
observation is required to show that there are also gradual
variations in the salinity of the water, its clearness, tem-
perature, and so on, while the aid of the geologist must be
invoked to demonstrate the fact that the land is undergoing
slow oscillations of level, stable and changeless as it may
seem. Now these constantly changing conditions have a
most important effect upon the littoral animals, for they
induce relatively rapid variation. For example, the Firth
of Forth, from a multitude of causes, grows muddier year
by year. We know that muddy water is fatal to many
organisms, owing to its forming a deposit on their delicate
324 LIFE BY THE SEASHORE.
breathing organs, and so asphyxiating the animals. But the
danger is so common that many animals — notably crabs —
have special means of filtering the water before it finds
access to the gills. In crabs the filtering arrangement is
obtained by spines and notches on carapace and claws, or
by hairs," all structures subject to variation. In the Firth of
Forth the increasing impurity of the water is certainly
eliminating certain animals, as it is probably contributing
to the increase of other mud-loving forms. In the case of
crabs, for instance, there must be, as it were, a premium on
the forms best adapted for filtering the water used in
respiration, for these only can thrive and multiply. The
result must be to produce relatively rapid variation, for the
progeny of parents which had both an elaborate filtering
apparatus will have a better chance of success than the
progeny of less specialised forms, or of a mixed union.
Similar variations of physical environment take place every-
where on the shore area ; as the conditions change and new
combinations occur, new places in nature are left vacant for
progressive forms, with the result that the shore area is one
where life is fast, and evolution rapid — it is not the place
for decadents or survivals. It is probable that this rapid
evolution has always occurred in the littoral zone, so we
should expect to find that the genera and species now living
in the area are modern in type, and may reasonably be
regarded as having arisen within the area. But where did
their progenitors come from? Has there always been an
abundant fauna, or can we go back to a period when the
shore waters were comparatively empty *? What relation has
the littoral fauna to the two other great faunas — the pelagic
and the abyssal ?
The answers to these questions are difficult and debated,
but it may be worth while to look for a little at the matter,
even if we cannot hope to reach a definite conclusion. In
the first place we may clear the way a little by excluding
the abyssal fauna from consideration. Its members are
strangely modified animals, which, there is reason to believe,
have been derived at very different periods from littoral or
pelagic forms. Apart even from the fact that these deep-sea
animals display many peculiarities of structure, the physical
conditions which prevail in the great depths — the darkness,
DISTRIBUTION OF SHORE ANIMALS. 325
the absence of plants, and the consequent limitation of the
food-supply, the low temperature, the high pressure, and so
on — make it very improbable that the most primitive
animals lived there. The problem before us, therefore, is
really, Were the primitive animals littoral or pelagic 1 The
evidence upon which the judgment must be pronounced is
derived first from the geological history of animals, and
second from their life-history.
What does geology teach us as to the origin and
antiquity of shore animals? The earliest fauna we know
is that of the Lower Cambrian rocks, and, especially in
America, numerous fossils have been obtained from these
beds. The fossils are, generally speaking, littoral in type,
and they show that even in those far-off days the main
classes of Invertebrates were distinctly marked off from one
another ; Coelentera, Echinoderma, Crustacea, Mollusca, were
represented then as now in the littoral waters, and their
representatives showed many of the characters of the littoral
forms of the present day. The presence of these numerous
littoral animals in these old rocks, coupled with the paucity
of pelagic forms, may seem to prove decisively the greater
antiquity of the former; but the apparent strength of the
argument is diminished by two considerations, In the
first place, though in those old rocks there are actually
imprints of jelly-fish, yet generally the animals which are
abundantly represented as fossils are those only which
were possessed of hard parts. Now, as we have already
seen, it is characteristic of shore animals that their hard
parts are well developed, while pelagic animals have usually
little in the way of skeleton. The abundance of fossil
littoral animals, even in very old rocks, may then be due
to the fact that these are readily fossilised, rather than to
their abundance relative to pelagic forms. Similarly, in
the second place, those old rocks were laid down not far
from land in relatively shallow water, so that littoral
forms only would be likely to become entombed in sedi-
ment, and so fossilised. In general, though geology shows
us that littoral animals are extraordinarily old, it virtually
tells us nothing as to their age relative to other animals.
We are thus thrown back upon the evidence derived
from a study of the life-history of littoral forms, but only
326
LIFE BY THE SEASHORE.
to find that it is so ambiguous that it is capable of inter-
pretation in two diametrically opposite ways. It may be
affirmed that (1) pelagic animals
have arisen from littoral ones,
and (2) littoral animals from
primitive pelagic forms, and both
positions can be supported by an
imposing array of arguments.
Think of the life-histories of the
littoral animals we have studied :
In the Coelentera we have often
an alternation of generations, the
life-history including a jelly-fish
stage adapted for a pelagic habi-
tat, and a fixed zoophyte stage
adapted for life on the bottom.
Among the worms there is usually
a larval pelagic stage ; a little
top-shaped larva called a trocho-
sphere occurs in the life-history
of most of the marine bristle-
worms, and is to be found near
the surface of the sea'. •» swims
should be contrasted with Fig. 6. by means of the motile threads,
Note short manubrium and the •!• -_i,' v. V* A
four tentacles. After Hincks. or cilia, which occur in bands
on the surface of the body, and
is later, by a process of metamorphosis, converted into the
more or less sedentary adult. The Echinoderms, again, as
we have already seen, have larvae very different in character
from the adults, and adapted for a free swimming and not
a sedentary existence. We have also emphasised the occur-
rence of pelagic larvae of many strange shapes among the
Crustacea, and a tow-netting at almost any season of the
year will show you that the surface-water simply teems
with these. The Mollusca also add their quota of minute
larval forms to the fauna of the open sea. Generally we
may say that although there are a few exceptions, yet it is
true of littoral animals as a whole that they produce minute,
active, pelagic larvae.
Further, these larvae are usually simple in structure, and
are often devoid of those peculiarities which are diagnostic
DISTRIBUTION OF SHORE ANIMALS. 327
of the class to which the adult belongs; thus the very
young mollusc is like a young
worm, and is without such struc-
tures as shell, foot, mantle, etc.,
which are characteristic of the
adults. Adult Echinoderms are
radially symmetrical, but the
larvse are bilaterally symmetrical ;
we might go on to give many
other examples, but these may
serve to make the point clear.
There can be no reasonable doubt
that in some cases these simple FIG. 91.— Naupiius of Peneus, a
larva, display what has been ff^J^fyyy^
aptly called " ancestral remi- Crustacea, and is very common
niscence"; that is, they display ^the^surface of the sea. After
ancestral features, which the
adults have lost. Thus the long tail of the megalopa stage
of the crab shows that crabs had long-tailed ancestors ; the
shelled larvse (veligers) of the common sea-slugs show that
these are descended from ancestors with shells. Can we,
then, say generally that the occurrence of pelagic larvse in the
life-history of littoral forms shows that these all had pelagic
ancestors 1 It would seem that such a view had much plausi-
bility, and yet there is a good deal to be said against it.
In the first place, when we study pelagic animals closely,
we find that while they often appear at first sight to be
extraordinarily simple and primitive, yet close examination
shows that they must have had complex and specialised
ancestors. Thus there are a great number of pelagic
molluscs, often without shell, sometimes without foot or
mantle, delicate and transparent in texture, simple, as one
might say, in structure, and yet closer study shows that
they are apparently descended from littoral forms with
distinct shell, foot, and mantle. The same thing happens
in other groups, and leads us to the conclusion that pelagic
animals in general are often, apparently as an adaptation to
their peculiar habitat, simple, delicate, and transparent
creatures, but this simplicity is adaptive and not primitive.
If armed with this deduction we return to the pelagic
larvse of littoral animals, we shall find some reason to doubt
328 LIFE BY THE SEASHORE.
our first hasty conclusion that these minute transparent
creatures are really simple — really represent the primitive
pelagic ancestors. The larvae must have means of keeping
themselves afloat, and these means are often wonderfully
elaborate; they often have curious spines and processes,
whose object seems to be to prevent them being engulfed by
a narrow-mouthed foe, but which are too complicated in
structure for us to believe that they could occur in a truly
primitive animal. These are common in Crustacean larvse,
and well shown in the accompanying figure. Another diffi-
culty is that in Echinoderms, where the occurrence of simple
pelagic larvae is so striking a characteristic, the larvse of
the different classes differ from one another markedly. For
example, we have seen that morphologically the brittle-stars
and starfishes are
nearly related, but
nevertheless the larvae
in the two classes
show marked differences. This at
once introduces a difficulty in regard
to ancestry, if we suppose that the
larvse represent ancestral forms.
Pro. Oi-Zoea of a crab(TWa . .
Note the long seems impossible to doubt that while
the adult starfish and brittle-stars
have been diverging, the larvse
have also been diverging along different lines. That is,
the common ancestors of starfish and brittle-stars must
have had larvse quite different from the larvse either of
existing starfish or existing brittle-stars, and if we endeavour
to discover the characters of those original larvse by studying
the common characters of starfish larva and brittle-star
larva, we find that this original larva becomes pretty vague.
Generally we may say that just as the apparent simplicity
of pelagic animals when closely studied becomes adaptive
rather than primitive, so the simplicity of the pelagic larvaa
of shore animals when closely examined no longer appears
to be due entirely to " ancestral reminiscence," but acquires
an adaptive significance.
This rather subtle argument would perhaps have little
force against the theory of the pelagic origin of shore
DISTRIBUTION OF SHORE ANIMALS. 329
animals, if we could not give a reason why pelagic larvae
showing adaptive simplicity should occur in the life-history
of shore animals. But a twofold reason is fairly obvious,
and has already been suggested by implication. Shore
animals usually have armour, are often sedentary, are rarely
strong or swift swimmers: the minute active larvae ensure
distribution ; in their own sphere they fulfil the same
function as the winged seeds of our great forest trees, and
their occurrence in the life-history is justified by this fact.
Again, Prof. W. K. Brooks (see his Foundations of Zoology
for details) suggests that this occurrence is also justified by
the fact that life on the whole is less precarious in the open
sea than near the shore. We have repeatedly emphasised
the fact that in the shore waters there are multitudes of
sedentary animals who live upon minute creatures found in
the water, and who are constantly creating miniature whirl-
pools in the water as they lash it through their bodies.
Against such maelstroms the young forms would have no
chance, so that it is safer for them to acquire more and more
purely pelagic characters, and get out into the open where
there are not so many hungry mouths ever ready for food.
We thus see that the arguments for the theory of the
pelagic origin of littoral animals seem to be nearly balanced
by the arguments against. Does the converse theory that
pelagic animals originated from littoral fare any better ? The
theory may be put in this way. Littoral animals send off
pelagic larvse out into the open, and the specialisation of
these larvae takes place along different lines from that of the
adults ; the larvae acquire elaborate mechanisms to keep
themselves afloat, forms of armour which may protect them
without adding greatly to the body-weight, such pale and
delicate colours as may render them inconspicuous in their
uniform background, and so on. Is it possible that long ago
some of these larvae forgot to grow up, if we may put the
matter so, and gave rise to the original pelagic animals 1 Is
the resemblance between pelagic animals and the pelagic
larvae of littoral animals due to the fact that the latter or
similar forms were long ago the ancestors of the first, in-
stead of to the converse relation 1 We shall not follow the
question in further detail — perhaps to some it may seem to
be identical with the momentous question whether the egg
330
LIFE BY THE SEASHORE.
or owl came first — but enough has been said to show that
the matter is worth thinking about. In closing, it may be
well to note that while on the one hand there are naturalists
who believe that the primitive animals were pelagic, and
on the other those who believe that they were littoral, there
is also a third and perhaps increasing school who hold that
while existing pelagic and littoral animals are interlocked
and interrelated in a thousand different ways, we have no
data at present from which we can discover
anything of the characters of the primitive
forms. Even those, however, who believe
that the open sea was the first home of life
do not deny that most of the existing
pelagic animals have passed through a lit-
toral phase, and then returned to the open
sea.
In the above discussion we have confined
ourselves to the evidence derived from In-
vertebrates, but those who follow the argu-
ment in larger works should not forget that
there is also a pelagic fish fauna, a pelagic
mammalian fauna (whales, dolphins, etc.),
even a pelagic insect. The last two cases
show that from land and air, as well as
FIG. 93.— Sea-goose- fr0m the shore, animals may return to the
berry, or Pleuro- ... » J
brackia, with the easy life of the open sea.
ed?taA peiagfcco?" &itol*l animals are not only interesting
lenterate with no on account of the question of their rela-
tion to pelagic forms, for we must think
also of their relation to the fresh -water and terrestrial
forms. Many shore animals live near the mouths of rivers
or streams, and not a few of them learn to tolerate a con-
siderable admixture of fresh water. By some such process
of gradual colonisation, we can suppose many fresh-water
forms to have originated. Periwinkles and some Crustacea
live at or near high-tide mark, and can tolerate free exposure
to the atmosphere ; it is reasonable to believe that in this
way some terrestrial Molluscs and Crustacea may have arisen
from littoral forms. The shore animals thus constitute a
most interesting group, and have relations with most of the
other great faunas of the globe.
DISTRIBUTION OF SHORE ANIMALS. 331
All this may, however, be objected to as somewhat
speculative, and it may be well to emphasise the practical
nature of this volume by briefly mentioning, in conclusion,
some possible lines of work for the shore naturalist. One
would naturally seek, in the first place, to acquire a general
knowledge of the common forms, and to obtain such an
acquaintance with species as to give one a general idea of
the meaning of specific differences, and ensure accuracy of
observation — the last being a quality of somewhat slow
growth. When this has been accomplished, the time for
specialisation begins. Possible lines of work are many.
For example, there is much to be done in regard to colour,
even looked at in its most external aspect. The range of
colour variation, the relation of colour to environment, and
kindred problems, are still untouched in many groups.
Most work in this respect has been done in Crustacea, but
Echinoderms and sea-anemones may be mentioned as suitable
objects for such investigations. Then the diet of many
shore animals is still very imperfectly known, and much of
the evidence points to the conclusion that in many cases the
food varies with the locality. Where this occurs the relation
of the diet to local variations in structure is obviously a
point of much interest. Again, many shore animals are
undoubtedly very variable, and the nature and extent of
this variation offers an interesting subject for investigation.
It seems probable that among the bristle-worms the range of
variation is very extensive, and that systematic investigation
would considerably reduce the number of so-called species.
In regard to the habits of even the commonest forms much
still remains to be done, and the keeping of isolated animals
in confinement might yield valuable results in this respect.
But this book is primarily addressed to the many, rather
than to the few who can spend much of their time in
scientific pursuits, so we may perhaps, in conclusion, urge
the beginner not to allow an interest in form or in
"problems" to obscure an interest in animals as living
creatures. It is much to learn to appreciate the charm of
the crowded shore area, to see the great drama of life which
unfolds itself there, as in other regions, to the patient ob-
server, and to realise something of the unity of nature, of
the order which runs through the apparent chaos of life.
SOME BOOKS OF REFERENCE.
Books marked thus * are those whose nomenclature has been employed in
the text.
GENERAL.
(1) A Manual of British Marine Zoology for the British Isles, by
P. H. Gosse. Two parts. London, 1855. Now out of print, but it
may occasionally be picked up second hand. In many ways it is a
most useful book.
(2) The Marine Invertebrates and Fishes of St. Andrews, by W. C.
Mclntosh. Edinburgh, 1875. Gives most useful lists, with many
notes on habits, distribution, and so on.
(3) The Marine Invertebrate Fauna of the Firth of Forth, by Herdman
and Leslie. Edinburgh, 1881. A similar work, but not quite so full.
In addition reference should be made to the works of Gosse, Lewes,
Woods, and others, most of which are published under general titles.
Further, the Reports of the different Biological Stations often contain
important faunal lists, etc. , for their special localities. See especially
the Journal of the Marine Biological Association, published at Ply-
mouth, and the Reports of the Liverpool Marine Biology Committee.
For details of structure reference should be made to the Outlines of
Zoology, by J. A. Thomson (third edition, Edinburgh and London,
1899), or to some of the books of reference named in 'it. As a book
of more elementary character, An Introduction to the Study of Zoology,
by B. Lindsay (London, 1899), may be mentioned.
SPONGES.
(1) *Bowerbank's Monograph of British Spongiadce (vols. i.-iv.,
1864-82) is the standard work, but it may be supplemented by —
(2) A Revision of Generic Nomenclature and Classification in
BowerbanTcs British Spongiadce, by R. Hanitsch, in Transactions of
Liverpool Biological Society, vol. viii., 1894.
CGELENTERA.
There is no English book dealing with the British representatives
of the entire group, but certain of the sub-classes have been fully
treated.
A. HYDKOZOA (Sea-firs, etc.).
(1) * Hincks's British Hydroid Zoophytes. London, 1868.
(2) Allman's Monograph of GymnoUastic Tubularian Hydroids. Ray
Society, 1871-2.
332
SOME BOOKS OF REFERENCE. 333
(3) Forbes's Monograph of the British Naked-eyed Medusce. Ray
Society, 1848.
(4) For modern terminology reference may be made to E. T.
Browne's British Hydroids and Medusce in the Proceedings of the
Zoological Society of London, 1896.
(5) Ellis's Essay towards a Natural History of Corallines (1755) is a
carious old book of considerable antiquarian interest.
(6) Johnston's History of British Zoophytes (Edinburgh, 1838) is
comprehensive as regards the ground covered, but the descriptions in
most cases are too vague to be of much use.
B. ACTINOZOA.
(1) * Gosse's History of the British Sea-anemones and Corals
(London, 1860) is the standard work on the subject, but for the
modern names of the British sea-anemones reference should be
made to—
(2) A Revision of the British Actiniae, by Haddon and Shackelton,
in Transactions of the Royal Society of Dublin, 1889 and 1891.
We are unfortunate in not possessing books which deal with the
British representatives of such forms as the allies of Dead Men's
Fingers (Alcyonium), Lucenaria, the large jelly-fish, the Ctenophora.
and so on. Some of these are dealt with in Johnston's British
Zoophytes.
WORMS.
(1) The volume called * Worms, Rotifers, and Polyzoa, in the
Cambridge Natural History (vol. ii., 1896), by various authors, is an
admirable introduction to the subject, especially as regards the Marine
Bristle-worms. It contains numerous references which will enable
those interested to pursue the subject further.
(2) Mclntosh's British Annelids (Ray Society, 2 vols., 1873 and
1900) treats in detail of the British species of Nemerteans and certain
families of Bristle-worms.
(3) Johnston's British Mu'seum Catalogue of Non-parasitical Worms
(London, 1865), though not very full, and vague in its descriptions, is
helpful in some ways.
ECHINODERMA.
(1) The standard work of reference is * Jeffrey Bell's Catalogue of
British Echinoderms in the British Museum (London, 1892), but it
will probably be found difficult to use.
(2) Forbes's British Starfishes (London, 1841), thougnout of date, is
well worth reading on account of the interest of the style.
CRUSTACEA.
(1) * Bell's History of the British Stalk-eyed Crustacea (London, 1853)
is the standard work on the higher forms, but it should be sup-
plemented by —
(2) Stebbing's History of Crustacea. London, 1893. International
Science Series.
334 LIFE BY THE SEASHORE.
(3) Norman's British Mysidce, a paper in the Annals and Magazine
of Natural History (vol. x., 1893), together with some other earlier
papers in the same Journal, will be found helpful, but their results
are to a large extent incorporated in Stebbing's volume.
(4) For certain of the lower forms Bate and Westwood's History of
the British Sessile-eyed Crustacea (2 vols., London, 1861-8) may be
consulted.
(5) White's Popular History of British Crustacea (London, 1857) is
a useful and comprehensive little book.
MOLLUSCA.
(1) * Forbes and Hanley's History of British Mollusca. 4 vols.
London, 1853.
(2) Jeffrey's British Conchology. 3 vols. London, 1863-9.
(3) Alder and Hancock's Monograph of British Nudibranchiate
Mollusca. Kay Society, 1845-55. All these works are well illustrated,
and should be consulted, if only for the plates. There are many
other works of greater or less extent on the British shell-fish, but
these may serve for purposes of identification.
(4) For modern names see Norman's Revision of British Mollusca, in
Annals and Magazine of Natural History, vols. v. and vi. (1890).
TUNICATA.
Although in Prof. Herdman we have an eminent British authority
on this difficult group, his publications have mostly appeared in
scientific journals which are not always readily accessible. Brief
notes on the British species are included in *A Revised Classification
of the Tunicata, etc., published in the Journal of the Linnean Society,
vol. xxiii., 1890 ; but this paper will hardly be intelligible to those
who have not considerable acquaintance with Tunicate anatomy.
The same author's article on Tunicata, in the Encylopcedia Britannica,
republished in a volume entitled Zoological Articles (London, 1890),
affords a valuable introduction to the subject. In Forbes and Hanley's
Mollusca brief descriptions of the external appearance of some common
sea-squirts are given.
FISHES.
(1) Day's Fishes of Great Britain and Ireland. 2 vols. London,
1880-4.
DISTRIBUTION, ETC.
(1) A paper on Tlie Fauna and Bottom- Deposits near the Thirty-
Fathom Line, etc., by E. J. Allen, in the Journal of the Marine
Biological Association (vol. v., 1899), gives a large amount of informa-
tion on the distribution of British forms, with very copioiis references.
Many of the works cited above also include distribution.
GENEEAL INDEX.
(TEXT AND ILLUSTRATIONS.)
Figures in italics refer to illustrations ; those in thick type to the
pages where technical terms are defined.
Abdomen of crayfish, 153
Aberdeen, 193
Aberystwyth, 35, 265
Abyssal fauna, 319, 324
Acontia, or stinging-threads, 66,
70
Adaptive characters, 297
Alnmouth, 35, 81, 265
Alternation of generations, 17, 64
Alveolus of Aristotle's lantern,
136
Ambulacral areas of sea-urchin,
1 37 / 38
Lot t loo
Ambulacral groove, 127
Ampullae of sea-urchin, 138
Anal fins of coal-fish, 298
Ancestral reminiscence, 327
Anchors of Synapta, 144
Annuli, or rings, 61
Antennae of lobster, 156
Antennules of lobster, 156
Anus, or posterior opening of the
food canal
of sea-urchin, 137
of Cucumaria, 143
of heart-urchin, 141
Arctic region, 321
Aristotle's lantern, 135, 136
Auditory organs of Mysis, 212
Autotomy, or self-mutilation, 11,
162 ; of Galathea, 176
Barbule of cod, 301
of saithe, 298
Base of sea-anemone, 65
Basipodite, 174
Beaks of mussel shell, 268
Bilateral symmetry, 143
Biramose appendages, 161
Boreal region, 322
Bournemouth, 35
Branchial sac of sea-squirt, 292
Brood pouch of Mysis flexuosa,
209
Buccal cavity of Nereis, 87
Burrowing animals, 7, 321
Bursse of brittle- star, 130
Byssus, 270
of mussel, 267
Carapace of crayfish, 155
of crab, 10
Cardinal teeth of Cyprina, 279
Carpopodite, 174
Cephalothorax, 153
Chelipedes of crayfish, 156, 161
Chitin of Crustacea, 150
Cirri of Nereis pelagica, 84, 88
of parapodia, 86, 95, 109
of Trochus, 235
Ccenosarc of Alcyonarians, 75
Collar of Sabellids, 116
of Serpula, 117
Column of sea-anemone, 65
Commensalism, 187
Coxopodite, 174
Dactylopodite, 174
Disc of Ophiura, 130
of sea-anemone, 65
335
336
LIFE BY THE SEASHORE.
Dorsal fins of coal -fish, 298
Dunbar, 35
Egg capsules of dog-periwinkle,
242 ; of whelk, 243
Eggs of Cirratulus cirratus, 111
of Dendronotus, 258
of Eulalia viridis, 102
of lobster, 173
of lumpsucker, 305
of Mysis, 210
Elytra, or scales of Polynoe, 94-6
of Sthenelais, 98
Epidermis of Cyprina, 279
Epipodia of sea-hare, 250
Exhalent aperture of mussel, 267
Exhalent siphon of Tapes, 268
Eyes of scallop, 274
Eye-spots of sea-urchin, 137
Falmouth, 35
Firth of Clyde, 35, 165, 276, 322
Firth of Forth, 20, 63, 81, 111,
165, 254, 261, 272, 275, 285,
295, 323, 324
Flagella of crayfish's antennae, 156
Foot-jaws of crab, 160
of crayfish, 156
of lobster, 160
Foot of limpet, 24, 226
of Molluscs, 33
Genital pits of Aurelia, 77
Gills of Arenicola, 30
of Cirratulus cirratus, 111
of Crustacea, 152
of Doris, 251, 252
of edible crab, 160
of limpet, 226
of Nerine, 110
of Nephthys hombcryii, 109
of Pectinaria, 115
of Sabellaria, 118
of Serpula, 117
of TereMla, 113
Gill separator, 160
Gizzard of crayfish, 157
Gland-shields of Arenicola, 91
of Terebella, 114
Gonothecse, 50
of Campanulai'iaflexuosa, 52
Gonothecse of sea-firs, 50
of Plumularia setacca, 57
of Sertularia pumila, 55
Head of Phyllodoce lamelligera,
100
Heteronereis of Nereis pelagica,
106 ; of Nereis virens, 107
Hinge of Tapes, 268
Hooks of Terebella, 113
of Sabellids, 116
Hydroid polypes, 44
Ilfracombe, 35, 193
Inhalent siphon of Tapes, 268
Interambulacral areas of sea-
urchin, 137, 188
Introvert of Glyceridse, 108
of Nephthydidae, 108
of Nereis pelagica, 87, 104
of Phyllodoce lamelligera, 100
Ischiopodite, 174
Jaws of Glycera capitata, 109
of Nereis pelagica, 87, 104
Joppa, 127
Lateral line of fish, 298, 300
Ligament of mussel, 268
of Cyprina islandica, 279
Littoral fauna, 319; origin of,
325 et seq.
Lusitanian region, 322
Lyme Regis, 35
Lynmouth, 170, 247
Madreporite, 126
of brittle-stars, 131
of heart-urchin, 142
of sea-urchin, 137, 138
of Solaster papposus, 128
Mandibles of crayfish, 156
Mantle of limpet, 24, 226
of bivalves, 227
Manubrium of medusoid, 17, 40
Masking of crabs, 14
Maxillae of crayfish, 156
Maxillipedes, 156
of edible crab, 160
of lobster, 160
Megalopa of shore crab, 206, 327
INDEX.
337
Meropodite, 174
Mesenteries of sea-anemones, 66
of Arenicola, 92
Millport, 35, 81
Moulting in crabs, 204
Mouth-papillse of Ophiura, 130,
131 ; of AmpUura, 133
Mouth-shields of Ophiura, 130
Mysis stage of Norway lobster,
'206
Nauplius of Peneus, 327
Nematophores of Plumularidse, 57
Nephridia, or kidney tubes, 29,
92, 93
Nerve-cord of Arenicola, 92
North Berwick, 35
Operculum of acorn-shell, 220
of coal-fish, 298, 300
of crabs, 194
of sea-firs, 53
of molluscs, 6, 244
of Serpula, 117
Orbits of crab, 160
Oscula of sponges, 38
Paignton, 35
Pallial sinus of Tapes, 268
Palps of Nereis pelagica, 84, 88,
104; of Tapes pullastra, 269
Papillae of Doto, 259
of Eolis, 260, 261
of Trophonia, 116
Paragnaths of Nereis pelagica, 104
Parapodium, 83, 84
of Nephthys homier gii, 109
of Nereis pelagica, S6
Pectoral fin of coal-fish, 298, 300
Pedicellarise of Echinoderms, 127,
135
Peduncle of crayfish's antenna,
156
Pelagic fauna, 2, 319, 325 et seq.
Pelvic fins of fish, 300
Pentamerous symmetry of sea-
urchin, 139
Penzance, 35, 63
Peristomium of worms, 84
of Nereis pelagica, 86
of Terebella, 112
Peri visceral fluid of sea-urchin,
139
Pharynx of fish, 300
of Nereis, 87
Pinnse, or branches of Hydrall-
mania falcata, 56
of Plumularia setacea, 57
Pinnate tentacles of Alcyonium,
75
Poly carps of sea -squirt, 294
Polymorphism, 45
Polype, a name applied to a mem-
ber of a Coelenterate colony, or
to a simple Ccelenterate, e.g. a
sea-anemone, 16, 41
Poole, 35
Portland, 35
Preoperculum of Coitus, 301
Proboscis of Arenicola, 30
of Nemerteans, 120
of Nereis pelagica, 87
Propodite, 174
Prostomium of Nereis pelagica, 84,
86
Protective coloration, 14, 256
Radial shield of Opkiothrix fra-
gilis, 129, 130
Radial or radiate symmetry, 29,
126, 143
Radula, 227
of Chiton, 228
of limpet, 226
Rostrum, 154
of Decapods, 163
of Galathea, 178
of Hippolyte varians, 167
of lobster, 173
of Nephrops, 174
of Palcemon, 165
St. Andrews, 35, 63, 81, 127, 193
Scale of crayfish's antenna, 156
of Mysis, 212
Scales of Polynoids, 95, 96, 97,
98, 102, 107
Scarborough, 35
Segmentation, 85 •
of Chiton, 229
Self-mutilation, 11, 126
Septa of bristle- worms, 91, 92
338
LIFE BY THE SEASHORE.
Siphon of whelk, 234, 844
Siphonoglyphes, 66
of Actinoloba dianthus, 74
Skin-gills, 128
Spawn of Doris, 253
of Doto coronata. 259
Spicules of Alcyonium, 75
Spicules or needles of sponges, 36
Sporosacs of sea-firs, 41> 42, 46,
48, 49, 50, 58
Squame of crayfish's antenna, 156
Stinging-cells, 29
Stolons, basal connecting pro-
cesses of sea-firs, shown in
Figs. IX. and XVII., 29, 51
Stone canal of sea-urchin, 138
Sub-chelate, 169
Sub-equivalve, 275
Swimmerets, 154, 156
Swimming movements of Deca-
pods, 253 [13
Symbiosis or animal partnerships,
Tail fan of crayfish, 157
Teeth of Cyprina islandica, 279
of Ophiura, 131
of sea-urchin, 136
Teignmouth, 35
Telson, 155
of Mysis, 212
Tenby, 35
Tentacle scales of Ophiura, 130
Tentacles of Cucumaria, 143,
144, 145 .
Tentacles of heart-urchin, 142
Tentaculocysts of Aurelia, 77
Test of common sea-urchin, 135
of Echinocardium cordatum,
of Tunicate, 291 [140
Thoracic membrane of Serpula,
117
Tooth-papillse of brittle-stars, 131
Torbay, 264
Torquay, 35, 63, 193
Tube of Pectinaria belgica, 114
of Pomatocerostriqueter, 117
of Serpula vermicularis,\!7
Tube-feet of Asterias rubens, 126,
of Cucumaria, 144 [127
of heart-urchin, 142
of Ophiothrixfragilis, 130
of sea-urchin, 137
Uropods, 157
Velum, or veil, of medusoids, 47
Ventral fin of coal-fish, 298
"Water-vascular system, 126
Weymouth, 35, 264
Whitby, 35
Woolacombe, 289
Zoea, 205
of Thiapolita, 328
Zooid, a member of an animal
colony, 41
INDEX TO
CLASSIFICATION AND NAMES OF ANIMALS.
(TEXT AND ILLUSTRATIONS.)
Figures in italics refer to illustrations ; those in thick type to the
page on which the animal is described.
Acmcea testudinalis, 23, 24, 232,
233, 246
A. mrginea, 232, 246
Acorn-shells, 6, 219
Actinia mesembryanthemum, 65,
67, 80
Actinoloba dianthus, 16, 73, 73,
80, 317
Adamsia palliata, 12, 187
Alcyonaria, 74, 80, 81
Alcyonium digitatum, 16, 20, 74,
80, 317
Ammodytes lanceolatus, 311, 316
A. toUanus, 9, 311, 316
Amphictenidae, 123
Amphipoda, 14, 215, 223
Amphiporus lactiftoreus, 120
Amphithoe podoceroides, 217
Amphiura elegans, 133, 148
Anarrhichas lupus, 307
Ancula cristata, 256, 256, 263
Angler, 303
Annelids, 29, 32
Anomia ephippium, 270, 287
Anthea cereus, 20, 65, 81
Anthozoa, 64, 80
Aphrodite aculcata, 96, 103
Aphroditidae, 102, 122
Aplysia hybrida, 250, 250, 263
Aporrhais pes-pelecani, 240, 246
Arenicola piscatorum, 30, 88, 92,
115, 119, 122, 124, 321
Arenicolidse, 122
Aristotle's lantern, 136
Arthropods, 30, 32
Ascidiella mrginea, 295
Asiphonate bivalves, 269
Astacidae, 171, 192, 208
Astacus flumatilis, 171
Asterias rubens, 127, 147, 149,
323
A. glacialis, 127, 147, 149, 323
Asteroids, 126, 147
Asterophyton, 223
Atelecyclus heterodon, 191, 193,
194
Aurelia aurita, 76, 81
Azygobranchia, 230, 246
Balanus balanoides, 219, 224
Beroe, 79, 81
Bivalves, 7, 31, 32, 227, 266 et seq.
Blackamoor's tooth, 245
Blennidse, 315
Blennius pholis, 10, 306, 307,
315
Blenny, 10, 308
Bony fish, 297
Botrylloides, 296
Botryllus, 296
Bottle-brush coralline, 56, 56
Brachiopods, 268
Brachyura, 194, 207, 208
Bristle-worms, 83 et seq.
Brittle-stars, 126, 129, 147
Brown cat, 98
Buccinum undatum, 244) 244,
247
Bullhead, 301, 302, 303, 309
Butter-fish, 307
339
340
LIFE BY THE SEASHORE.
Calyptoblastea, 44, 49, 61, 81
Campanularia flexuosa, 51, 52,
61, 62
Campanularidfe, 61
Campanulinidee, 53, 61
Cancer pagurus, 26, 200, 208
Caprella linearis, 218
C. tuberculata, 219
Caprellicke, 223 [208
Carcinus mcenas, 26, 153, 200,
Cardium edule, 282, 288
Candida, 164, 170, 172, 208
Carpet-shell, 868, 281
Catometopa, 202, 207, 208
Cave-dwelling anemone, 14, 70
Centronotus gunnellus, 308, 308,
315
Cephalopoda, 228, 285
Chsetopoda, 83, 102
Chiton fascicularis, 229, 246
C. marginatus, 228, 229, 246
G. ruber, 230, 246
Chitonidae, 231, 246
Chlorhsemidse, 123
Chrysaora, 77
Ciona intestinalis, 291
Cirratulidee, 123 [124
Cirratulus cirratus, 111, 119, 123,
Cirripedia, 219, 224
Clava squamata, 45, 45, 61
C. multicornis, 61
Glytia johnstoni, 51, 62, 326
Cockle, 282
C(Blentera, 29, 32, 40, 61
Corals, 75
Corellaparallelogramma, 292, 292
Coryne pusilla, 46, 61
Corystes cassivelaunus, 189, 190,
193
Corystidse, 189, 192, 193, 208
Cottidse, 315
Coitus scorpius, 34, 301, 301, 315
C. bubalis, 302, 315
Cowry, 245
Crangon vulgaris, 168
Creeper, 107, 119
Crenella marmorata, 271, 273,
287
Crinoids, 126
Crumb-of-bread sponge, 28, 32, 37
Crustacea, 30, 32, 150 et seq.
Ctenophora, 79, 81
Cucumaria lactea, 143, 148, 149
C. pentactcs, 149
C. planci, 144
Cuttles, 31, 228, 285
Cyanea, 77
Cyclometopa, 199, 207, 208
Cydopterus lumpus, 21, 304. 315
Cyprea europcea, 245, 247
Cyprina islandica, 279, 287, 289
Dab, 314
Daisy anemone, 81
Daisy brittle- star, 132
Dasychone bombyx, 116, 123, 124
Dead men's fingers, 16, 74
Decapoda, 153, 170, 207, 223
Dendronotus arborescens, 256, 264
Discoboli, 315
Discomedusse, 81
Dog-periwinkle, 241
Donax vittatus, 280, 288
Doris bilamellata, 252, 263
D. johnstoni, 251, 252, 263
D. pilosa, 254, 263
D. repanda, 252, 263
D. tuberculata, 251, 263
Doto coronata, 13, 259, 259, 264
Echinocardium cor datum, 9, 139,
148
Echinoderms, 30, 32, 125 et seq.
Echinoids, 126, 148
Echinus esculentus, 135, 138, 138,
148
E. miliaris, 135, 148, 149
Edible crab, 26, 151, 200, 208
Edible mussel, 71, 267, 271
Eledone cirrosus, 286
Entomostraca, 219, 224
Eolis coronata, 22, 260, 264
E. papillosa, 260, 264
E. rufibranchialis, 261, 261, 264
Esop prawn, 151
Eulalia viridis, 101, 103, 119
Eulamellibranchs, 270
Eupagurus bernhardus, 193
E. prideauxii, 193
Father-lusher, or lucky proach,
301
INDEX,
341
Fiddler- crab, 201
Filibranchs, 270, 287
Filigrana implexa, 118
Fishing-frog, or angler, 303
Flatfish, 312
Flounder, 312, 314
Flustra, 120
Flustrella, 122
Fusus antiquus, 244, 247
F. islandicus, 244, 245, 247
Gadidje, 316
Gadus virens, 298, 299, 316
Galathea, 22, 175, 189
G. squamifera, 177, 177, 192
G. strigosa, 178, 192
Gammarus locusta, 217
Gasteropoda, 31, 33, 227, 246, 264
Gasterosteidae, 315
Gasterosteus, 10
G. aculeatus, 310, 315
G. spinachia, 309, 315
Glycera, 119, 122, 321
G. capitata, 108, 109, 124
G. gigantea, 109
Glyceridse, 108, 119, 122
Goby, 21
Goniodoris nodosa, 254, 255, 263
Gooseberry sea-squirt, 294
Gorgon-headed starfish, 223
Grantia ciliata, 39
G. compressa, 28, 38
Gunnel, 307, 308, 308
Gyranoblastea, 44, 61, 81
Haleciidse, 53, 62 [319
Halecium halecinum, 53, 54, 63,
HalicJiondria panicea, 37 [81
Haliclystus octoradiatus, 78, 7S,
Heart-urchin, 9, 139, 321
Helcion pcllucidum, 23, 232, 246
Henricia sanguinolenta, 127, 147,
149, 319
Hermit-crab, 12, 183, 184
Herring-bone coralline, 53, 319
Hippolyte cranchii, 167. 170, 321
H. varians, 167, 170
Holothurians, 126, 143, 148
Homarus vulgaris, 152, 171, 173,
192
Horse-mussel, 271, 273
Hyas araneus, 14, 196, 197, 207
H. coarctatus, 198, 207
Hydractinia echinata, 12, 41, 61,
63
Hydrallmania falcata, 56, 63
Hydra-tuba, 76
Hydrozoa, 43, 61, 81
Idotea tricuspidata, 215, 216, 216,
223
Inachus dorhynchus, 199, 207
/. dorsettensis, 14
Invertebrates, 27, 31
Isopoda, 215
Jelly-fish, 17, 64, 76
Lacuna, 236
Lafoea dumosa, 53, 63
Lafoeidse, 53, 62
Lamellar ia per spicua, 241, 246
Lamellibranchs, 227, 266 et seq.
Lamp-shells, 268
Leaf-worms, 98, 119
Lepas anatifera, 220
Leptoplana tremellaris, 119
Lima Mans, 273, 277, 287, 289
Limpet, 6, 24, 226, 231
Linens marinus, 120, 121, 121
Lithodes maia, 187, 188, 193, 195
Lithodidse, 192, 193, 208
Littorina, 236
L. littorea, 238, 246
L. neritoides, 238
L. oUusata, 238, 246
L. patula, 238
L. rudis, 238, 246
Living film, 119
Lobster, 152, 171, 192
Lob-worm, 11, 30, 83, 92, 115
Loligo vulgaris, 286
Lophius piscatorius, 303, 315
Lucenaria, 78, 78
Lucenarise, 81
Luidia, 134
Lumpsucker, 21, 304
Lutraria, 9, 321
Lutraria elliptica, 283, 288
Macrura, 162, 208
Madra solida, 280, 287
342
LIFE BY THE SEASHORE.
M. stultorum, 280, 280, 287
M. subtruncata, 280, 287
Maia squinado, 195, 207
Malacostraca, 219, 223
Masked crab, 189
Medusoids, 42, 46
of Clytia, 60
of Obelia, 60
Meiribranipora, 122
Modiola (or Crenella) marmorata,
12, 271, 273
M. modiolus, 271, 273, 287
Mollusca, 31, 32, 225 et seq.
Mya, 9
M. arenaria, 283, 288
M. truncata, 283, 283, 288
Mysidffi, 211, 223
Mysis, 161
M. flexuosa, 209, 211, 212, 223
M. lamornce, 214, 223
M. vulgaris, 213, 223
of Norway lobster, 205
Mytilus edulis, 267, 271, 272, 287
Nassa incrassata, 242, 247
N. reticulata, 242, 247
Natantia, 163, 164, 170, 208
Nauplius of Peneus, 327
Nematoda, 82
Nemertea, 29, 82, 120
Nephrops norvegicus, 151, 171,
174, 192, 322
Nephthydidse, 108, 122
Nephthys, 98, 119, 122
N. hombergii, 108, 123
Nereidse, 122
Nereis cultrifera, 106, 119, 123
N. dumerilii, 106, 123, 124
N.fucata, 12, 94, 106, 123
N. pelagica, 84, 85, 104, 119, 123,
124
N. virens, 107, 119, 123
Nerine, 119, 122, 321
N. coniocephala, 110, 124
N. vulgaris, 110, 124
Noctihica, 28
Norway lobster, 151, 171, 174,
192, 322
Notodelphys ascidicola, 294
Nudibranchs, 13, 248
Nymphon, 222, 224
Obelia geniculata, 51, 51, 62
Octopus vulgaris, 286
Old maid shell, 9, 283
Oligochsetes, 83
Ommastrephes todarus, 286
Opercularella lacerata, 53, 62
Ophidiidse, 316
Ophiocoma nigra, 149
Ophiopholis aculeata, 132, 148
Ophiothrix fragilis, 129, 131, 147
Ophiura albida, 133, 148
0. ciliaris, 133, 148
0. lacertosa, 133
Ophiuroids, 126, 129, 147
Opisthobranchia, 230, 248 et seq.
Opossum-shrimp, 205, 209
Ostrea edulis, 278, 287
Otter-shell, 9, 283
Oxyrhyncha, 195, 207, 208
Oyster, 278
Paddle-cock, 305
Paddle-worm, 99, 119
Paguridre, 183, 192, 193, 208
Pagurus bernhardus, 184, 186,
322
P. prideauxii, 187, 322
Palcemon serratus, 151, 165, 170
P. squilla, 151, 165, 170
Palinuridse, 174, 192, 208
Palinurus vulgaris, 174, 178, 192
Palolo Avorm, 105
Paludina, 236
Pandalus annulicornis, 151, 166,
170
Patella vulgata, 23, 226, 226, 231,
246
Peachia, 9, 321
Pearly nautilus, 228
Pecten maximus, 276, 287
P. opercularis, 31, 274, 287
P. pusio, 27 Q, 287
Pectinaria, 94, 119, 123
P. belgica, 114, 115, 124
Pediculati, 315
Pelican's foot, 240
Peltogaster paguri, 185, 220
Peneus, 164, 172, 327
Pennatula phosphor ea, 75, 80
Periwinkles, 236, 238
Pholas, 8, 284, 289
INDEX.
343
P. Candida, 285, 288
P. crispata, 8, 285, 288
Phoxichilidium femoratum, 222,
224
Phyllodoce lamelligera, 99, 100,
103, 119
P. maculata, 99, 103, 119
Phyllodocidre, 98, 122
Physalia, 63
Pinnotheres pisum, 202, 208
Pisa, 198
Plaice, 313, 314
Pleurobrachia, 79, 81, 330
Plcuronectes flesus, 314, 316
P. limanda, 314
P. platessa, 314
Pleuronectidse, 316
Plumose anemone, 16, 72, 73
Plumularia setacea, 29, 57, 57, 63
Plumularidse, 57, 62
Polycarpa rustica, 295
Polyccra quadrilineata, 255, 263
Polycheeta, 30, 83, 93, 102
Polynoe, 119
Polynoe imbricata, 95, 103
Polyzoa, 121
Pomatoccros triqueter, 117, 124
Porcelain-crab, 175, 179
Porcellana, 175, 189
P. longicornis, 180, 183, 192
P. platycheles, 179, 182, 191, 192
Porcellanidse, 192, 208
Portuguese man-of-war, 40, 45, 59,
63, 81
Portumnus variegatus, 201, 208
Portunus depurator, 202
P. marmoreus, 202, 208
P.puber, 201, 208
Prawn, 151, 163
Protozoa, 27, 32
Pseudo-lamellibranchs, 270, 287
Purple heart-urchin, 143
Purple-tipped urchin, 135
Purpura lapillus, 241, 247
Purse-sponge, 28, 32, 38
Pycnogonida, 221, 224
Pycnogonum littorale, 221, 224
Rag- worms, 109
Razor-shell, 2, 284
Reptantia, 163, 170, 192, 207, 208
Ribbon-worm, 9, 32, 120
Rissoa, 240
Rock lobster, 174, 192
Sabellaria alveolata, 7, 83, 118,
119
Sabellidse, 116, 123
Sabellids, 119
Sacculina carcini, 220, 221, 224
Saddle-oyster, 270
Sagartia bellis, 81
S. miniata, 81
S. troglodytes, 70, 70, 81
Saithe, or coal -fish, 298, 298 et seq.
Sand-eel, or sand-launce, 9, 311
Sand-hoppers, 215, 216, 817
Sand-mason, 7, 111
Sand-stars, 130, 133
Sarsia, 17, 46, 47
Saxicava rugosa, 8, 284, 288
Scale-worm, 95
Scallops, 31, 274
Scaly squat-lobster, 177, 177
Schizopoda, 164, 211, 223
Scyphomedusse, 81
Scyphozoa, 64, 80
Sea-cucumbers, 126, 143,^, 148
Sea-firs, 17, 43
Sea-gooseberry, 79, 330
Sea-hare, 250, 250
Sea-lemons, 250
Sea-lilies, 126
Sea-mat, 121
Sea-mouse, 96
Sea-nettles, 40
Sea-pen, 75
Sea-scorpion, 21, 34, 801, 301
Sea-slugs, 248
Sea-snake, 120, 121
Sea-spiders, 221, 224
Sea-squirts, 290, 292, 295
Sea-urchin, 126, 135, 138, 148
Segmented worms, 29, 32
Serpula vermicularis, 6, 90, 94,
117, 117
Serpulidse, 116, 123
Serpulids, 119
Sertularella polyzonias, 54, 63
Sertu laria putnila, 55, 63
Sertularidae. 54, 62
Shanny, 306
Shore crab, 26, 151, 153, 200
344
LIFE BY THE SEASHORE.
Shrimp, 168
Sickle-coralline, 56
Siphonate bivalves, 269
Siphonophora, 59
Siphonostoma, 94, 116
Siriella armata, 214, 223
Skenea planorbis, 240
Smooth anemone, 65
Solaster end&ca, 129, 147
S. papposus, 128, 128, 147
Solen, 9, 321
S. ensis, 284, 288
S. siliqua, 284, 288
Spatangus purpurcus, 143, 148
Spider-crabs, 14, 195, 197 > 321
Spiny spider-crab, 195
Spiny starfish, 149
Spionidse, 122
Spirorbis, 6, 83, 118
Sponges, 28, 32
Starfish, 125-9, 147, 149, 322
Stenorhynchus longirostris, 322
S. phalangium, 198, 207, 322
Sthenelais boa, 97, 97, 103, 119
Stickleback, 10, 309
Stone-crab, 187
Styelopsis grossularia, 294
Sun-star, 128, 149
Swimming-bells, 17, 47, 326
Swimming crabs, 201
Syllis, 105
Synapta, 9, 144, 148, 321
S. inhcerens, 145
Syncoryne eximia, 46, 61
Talitrus saltator, 216
Tapes pullastra, 268, 268, 281,
288
T. virgineus, 282
Tealia crassicornis, 67, 68, 68, 80
Teleosteans, 297, 315
Tellina tennis, 281, 288
Terebella, 7, 83, 90, 113, 123
T. conchilega, 111, 113, 124
Terebellidse, 123
Terebellids, 111, 119
Themisto brevispinosa, 215
Thick-horned anemone, 67, 68
Thuiaria thuia, 56, 56, 63 .
Tortoise-shell limpet, 23, 24, 233
Tower-shells, 240
Triopa claviger, 255, 263
Trochus cinerarius, 235, 246, 247
T. lineatus, 247
T. umUlicatus, 247
T. zizyphinus, 285, 246
Trophonia plumosa, 115, 119, 124
Tubularia indivisa, 29, 32, 48,
49, 61
Tunicates, 31, 290
Turbellaria, 119
Turritella communis, 240, 246
Unsegmented worms, 29, 32
Velvet-crab, 201
Venus striatula, 281, 288
Viviparous blenny, 308
Water-flea, 219, 294
Weever, 34
Whelk, or buckie, 844, 244
White cat, 98, 108
Wolf-fish, 307
Wrinkled swimming crab, 202
Zoantharia, 80, 81
Zoarces viviparus, 308, 315
Zoophytes, 12, 17, 40, 41, 43
Zygobranchia, 230, 246
VV. BKENDON AND SON, LIMITED, PLYMOUTH
MM 01 WOH G
YOUNG COLLECTOR SERIES
Fully Illustrated. Crown Svo, Cloth. Each ONE SHILLING.
ANTS, BEES, WASPS, AND DRAGON FLIES - W. H. BATH.
BIRDS (British) - - REV- H- A- MACPHERSON.
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SERG. CALLAGHAN RECOMMENDS
MEAD 'FLYER' CYCLES.
^
Gentlemen,— The Bicycle I purchased from your firm in 1901 has given me
entire satisfaction. I have now used it for four years, and during that period have
travelled over all classes of roads both in summer and winter; its durability and
hill-climbing capacity could not be excelled. Although 13 stone in weight, I have
ridden the machine 5,000 miles and judging from its present appearance it will cover
another 5,000 miles ivithout any danger of breakdown. These facts speak for
themselves. Yours faithfully, R. CALLAGHAN, Serg
MEAD FLYERS
as speed, and will outlast any other cycles
made. WARRANTED Six YEARS. PACKED FREE,
CARRIAGE PAID, AND TEN DAYS' TRIAL ALLOWED
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"els 1
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ff II. n I lit rfltt AH I DUUIV and marvellous Bicycle offer ever
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Call or write to-day. Open evenings till 9.
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MT An /»V/»f F f*n n/»«f 01« n Gla-£ow: 168, Buchanan Strut.
mtAU UYGLt. CO. Dept. 216 K. i)ub|fn: Ig7( Brunswick Strett.
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UNIVEESITY OF CALIFORNIA LIBEAEY,
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MAR 12 1932
JAN 31981
75m-7,'30
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