rumber 9

June 1, 1954

WEST COAST
MARINE SHELLS

F»l»i»l.>«».M.i.l—.l«|.l>HWI»M 11.11111. 1^.1

rine Biological laboratory
X. I 13 ii A R. Y

I 16 195f

5y WOODS HOLE, MASS.

MYRTLE E. JOHNSON

The Publication Committee desires to ex-
press to Dr. Myrtle E. Johnson its appreciation
of her assignment to the San Diego Society of
Natural History her copyright covering the with-
in publication.

PREFACE

An attempt is made in these few pages to give information whicli
will enable young students to classify the marine shells. California
has a long shore line which offers such diverse types of habitats that
the complete list of moUusk species would be a long one. Only a
small number from this long list can be included here because of
limited space. In selecting species most likely to be found in the
north, we have had to include some that are rarely found in the south
and others common in the south that are never found in the north.
Again, any collector on his first trip to the beach may happen to
pick up a species that is found only rarely. This chance for surprises
makes collecting interesting but it also makes it quite impossible to
list all the shells that will be found even in a small school collection.
Although there are sure to be shells in tjie school cabinet that are
not included here, the general information will enable the student to
assign his shells to their classes and in some cases to genera and
species.

Scientific keys necessitate reference to anatomy of the soft parts
of the mollusk and the use of technical terms. Such material would
probably not attract the young student. To avoid this difficulty and
to conserve space for a more extended list of shells, the pictures were
made in the hope that this "short cut" method of .identification will
make the guide more usable and more interesting for the students.

The author expresses appreciation to Miss Edla L. Schreiner,
Assistant County Superintendent of Schools, Ventura, for suggestions
for pupil activities, and to Ian Moore for hel]) in selecting the list of
shells to be included. Unless otherwise credited, drawings and ])hoto-
graphs were made by the author.

Myrtle E. Johxsox

CONTENTS

Page

Preface i

Classifying Shells 2

Chitons 3

Key to Identification of Chitons 5

Bivalve Shells 7

Tooth Shells 17,

Snail-like Shells 15

Nautilus Shells 27

Suggestions for Pupil Activities 29

Collecting Specimens 29

Preparing Specimens 29

Conserving Shore Animals 30

Poisonous Clams and Mussels 30

Activities for Lower-Grade Pupils 30

Activities for Upper-Grade Pupils 34

Glossary 33

Bibliography 34

West Coast Marine Shells

A shell collection gives its owner great pleasure not only because
the shells are beautiful, but also because the shell collector has the fun
of numerous picnics and collecting trips to the lakes, streams, and
beaches. Here he also gets acquainted with the soft-bodied mollusks
that build the shells and he sees something of how they live. Then
after the collector has prepared the shells for his cabinet, they show
such interesting variety in form and coloring that he enjoys looking
at them again and again. Unlike some kinds of collections, shells are
durable and keep their colors for years, and if well cleaned are not
attacked by the troublesome museum pests.

The animals that build the shells and live in them are known as
mollusks. This name comes from the Latin word iuolHs which means
soft. The different mollusks are all alike in being soft-bodied, unseg-
mented animals though they may be quite different in shape and size.
A certain part of the moUusk body, the mantle, has the power of
secreting the shell; that is, these mantle cells take from the material
that comes to them by way of the blood stream, certain substances
whi<jh they can combine and deposit in the form of hard shell.

Examination of thin sections of shell of one clam under the micro-
scope showed three different layers; the outer periostracum is thin and
more or less horny or skinlike; the prismatic layer is thicker and made
up of microscopic prisms; and the inner, nacreous layer is smooth, often
pearly or iridescent. The last-named layer is built by the cells of the
mantle that are in contact with the inside of the shell over'a considerable
area. Thus the thickness of the shell is gradually increased at all points
where secreting cells of the mantle contact the shell. The periostracum
and prismatic layers are added only at the edge of the shell and are pro-
duced by the cells near the outer border of the mantle.

The surface of almost any shell will show the lines of growth
which mark successive additions put on by the mollusk as it grew.
Sometimes, if one examines a shell closely, he can discover something of
the mollusk 's past history; perhaps there is a place where at one time
the shell was broken along the edge and later repaired by its owner as
succeeding layers of shell were deposited at the broken spot.

It would be interesting to know the rate of growth of all our shells.
The growth of the Pismo clam has been carefully studied and the
size from year to year recorded. The average age of four-inch Pismo

1

2 SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

elams is five years. As in the case of human animals, the rate of
growth is probably faster when food is plentiful and temperature
favorable than it is under difficult conditions. Dr. Bartch^ says the
oyster is adult at about five years and may live as long as ten and that
fresh water mussels, Anodonta, may live for thirty years.

'Mollusks live in a variety of places, on rocky or sandy seashores,
at the surface or deeper in the sea, in fresh-water lakes and stieams,
on land, or even in the tree tops.

CLASSIFYING SHELLS

In learning to sort or classify mollusks so that we can call them
by name, the first step is to divide the large group or phylum into
classes. By the shape of the body and the number of parts or voices
that make up the shell one can quickly determine the class to which a
mollusk belongs.

Phylum Mollusca

A. Shell witli more than two parts or valves.

Chitons (lass Amphineura

A'. Shell absent or with one valve or two.

B. Shell in two parts, hinged together {hivalve).

Oysters, clams Class Fehcypoda

B'. Shell in one part {univalve) or absent.

C. Shell tusk-shaped, small, and open at both ends.

Tooth-shells Class Scaphopoda

C. Shell coiled, pen-shaped, or absent.

D. Shell absent, internal and pen-shaped, or coiled and
divided into a series of distinct chambers. Foot of
living mollusk divided into eight or ten long arms
provided with numerous suction disks.

Octopus, squid Class Cephalopoda

D'. Shell absent or .more or less coiled. Foot of living
mollusk flattened for crawling or winglike for swim-
ming.
Snails, slugs Class Gastropoda

Each of the classes will be described in a general way and some of
the more common representatives of each class will be named. If the
student fails to find some of his shells described or illustrated, he

^ R. S. Bassler, and Others, Shelled Incertehrates, Smithsonian Scientific Series,
Vol. X, New York: Smithsonian Institution Series Inc.. 1931, p. iT.f..

WEST COAST MARINE SHELLS 3

should look for them in one of the larger books listed in the bibliog-
raphy. There are so many kinds of shells found in California that it
takes many volumes to describe and diagram them all. If none of
these pictures and descriptions quite fit the shells that the student is
trying to identify, they will, at least, give him a clue which will help
him to find them in the larger books on the subject.

Students sometimes wonder why two shells which appear to look
a good deal alike belong in different families. This is because the
classification is based on the structure of the moUusk body rather than
wholly on its shell, and there nuiy be diiferences in the structure of the
animal that can not be known from a study of the shell alone.

The different books sometimes seem to disagree as to the name of a
given shell. Shells bear the names given them by the persons who
first described them. Sometimes it has happened that a number of
persons have described the same shell under different names, each
person not knowing that the shell had already been described and
named. In many cases shells have been known for a long time by one
name and then a still older name and description is found. In such a
case, according to the rules, this oldest name is the one by which the
shell must thereafter be known. The student who is interested in
learning more about the rules for classifying and naming species will
want to read chapter two in Josiali Keep's West Coast Shells.^

CHITONS {Amphineura)

The chitons, which cling fast to the rocks, are easily recognized
since they are so different from the other mollusks. The eight over-
lapping plates or valves covering the upper, or dorsal surface are
surrounded by a girdle. One sometimes finds these separate plates
among the wave-washed, broken shells on the beach. The middle ones
are often called butterfly shells and the end ones false teeth shells. In
most species of chitons the girdle is narrow and covers only the outer
ends of the plates ; but in the Black Chiton, only a narrow strip of the
plates is visible inside the wide girdle, and in the Giant Chiton, the
rough, leathery covering extends entirely over the plates (Figure 2).

The large, flat, muscular foot enables the animal to cling to the
surf-beaten rocks. Some live up near high-tide line where they are
out of water for a large part of each day ; some are farther out where
they are only uncovered at the lowest tides; and many kinds are to
be found in the daytime clinging to the under side of rocks sheltered
from the light. Chitons are vegetarians, living on the seaweeds that
grow on the surface of the rocks. A long filelike tongue or radula is

1 Josiah Keep, West Coast Shells. (Revised by Joshua L. Baily, Jr ) Stanford
University: Stanford University Press, 1935.

4 SCIENCE GUroE FOR ELEMENTARY SCHOOLS

used to rasp off the seaweed. The radula is armed with regular rows
of teeth which are replaced as fast as they are worn away. The radula
is somewhat like that of the gastropod, Buccinum ( Figure 1 ) . The gills
of the animal are in the mantle cavity which lies between the foot and the
mantle

Figure 1. Teeth and the Radula of the Snail Buccinum (greatly magnified)

Figure 2. Collecting a Giant Chiton

WEST COAST MARINE SHELLS 5

III size, chitons rangQ from small kinds less than one-half an inch
long when fully grown, up to the Giant Chiton which may reach ten
inches in length. As the animal grows, material is added at the edges
of the plates.

The following key will help identify the nine species of chitons
pictured. The person using the key should first decide between A
and A' ; if A' fits, he should go on to B and IV, and so on until he comes
to a description that applies to his specimen. iNFany more species and
varieties are to bo found on the coast. The larger books listed in
the bibliography may be consulted for more.

The letters N., C. and S. indicate whether the species is found
on the northern, central, or sout^iern beaches of California. Upper
end is the anterior, or head end. in the figures of chitons. The size given
in the descriptions which follow i-epresents the usual dimensions of
large full-grown specimens. If the specimen is young, it may be much
smaller.

KEY TO IDENTIFICATION OF CHITONS

A. A'alves coinpletely concealed under dark red, leathery covering. Length : eight
inches or more. N.C. Giant Chiton, Crt/pfochiton sfelini, (Figure 2).

A'. Valves not completely covered by girdle (Figure :\) .

B. Black girdle covers at least two-thirds of each valve. Length: three inches.
N.C.S. Black Chiton, Katharina titnicata.

IV. Girdle covers less than half of each valve.

C. A'alves plainly marke<l with parallel, wavy lines. N.C.S. Length : one

inch or more. Lined Chiton, Tonicella lineata.
C'. A''alves not marked with distinct wavy lines.

D. Width less than one-half the length.

E. Attains length of three inches or more. Under rocks in the day-
time. Well-marked sculpturing on the valves. Light green.

F. Anterior valve concave. Girdle bears microscopic spines.

C.S. Conspicuous Chiton, Ischnochiton conspicnus.
v. Anterior valve straight. Girdle bears microscopic scales.

N.C.S. Gray Chiton, Ischnochiton heathiana.

E'. Attains length of one and a half inches. Usually found on upper
side of rocks in the daytime. Valves dark brown or greenish
with irregular white spots where valves are worn. N.C.S.
California Chiton, Nuttalina califoi-nka.

D'. Width more than half the length.

E. Girdle wider in front, with scattered hairs. N.C.S. Length:

reaches two inches. Veiled Chiton, Placiphorella velata.
E'. Girdle about the same size all the way around.

F. Valves and girdle smooth except for microscopic granules.
Dull, olive green. Length: one inch. N.C.S. Hart\^.»g's
Chiton, Cyanoplax hartwegii.

SCIENCE CUIDE FOR ELEMENTARY SCHOOLS

F'. Vnlves marked with sculptured pattern. Girdle -with stiff,
curling hairs.
G. Curled, straplike hairs of girdle bear bunches of short,

white thorns or spines which may be seen with the aid

of a hand lens. Length : two inches. N.C.S. Mossy

Chiton, Mopalia ciliata.
(i'. Curled hairs of girdle without short, white spines.

Length : two inches. N.C.S. Hairy Chiton, Mopalia

muscosa.

Bl.tck Chiton

California Chiton

1 l.irt >^ cj^'s C hiton

Mossy Chiton

Figure 3. Chiton Shells

WEST COAST MARINE SHELLS 7

BIVALVE SHELLS (Pelecypoda)

A clam builds a pair of shells called valves and is therefore known
as a bivalve. The two valves are joined at one point, called the hinge
and can be opened and closed. When the clam is alive, the two shells
are held together by muscles. Each muscle is attached to the inner
surface of both shells and when the muscle contracts, the two valves
are pulled together. When the muscles relax, the elastic ligament at
the hinge springs the valves apart.

Some clams can close their shells completely while the valves of
others are so made that they gape at one or both ends even when the
muscles are contracted.

An empty clam shell, unless it is badly worn, still shows the place
where the muscles were once attached and also the line where the
mantle attached to the shell (Figure 4). When a living clam in sea
water gapes and shows its fleshy parts the mantle can be seen as thin
tissue lying close to the inside of each valve (Figure 6).

The clam has no radula or rasping organ for biting off its food.
It feeds by drawing in a current of water laden with tiny organisms.
These countless microscopic plants and animals are carried to the
mouth by the currents of water. The locations of the various organs
and shell landmarks are shown in the diagrams (Figures 4-7). Some
bivalves live deep in the mud (Figure 7) while others do not burrow
at all. This explains the fact that some need long siphons for con-
veying the water current while others have short ones and still others
have none. The siphons are two tubes (Figure 6), one of which con-
veys water and food to the clam and the other carries water and
waste material away.

When the clam is burrowing downward, the lower end is called
the front or anterior end, and the upper end from which the siphons
extend is the hinder or posterior end. The pallial sinus (Figure 4)
marks the siphon end. Figures 4 and 5 also show how to take the
measurements of length, height, and diameter. As the figure shows,
the distance through the clam at the point where it bulges most is the
diameter. Thickness refers to the thickness of the shell material of
a valve.

The water also serves to bring air to the animal. The gills are thin
structures which hang down in the mantle cavity where the water can
wash over them. The colorless blood flows through the gills and
oxygen can pass into the blood through the thin tissue. Carbon di-
oxide passes from the blood out into the water and is carried away in
the current. The water is propelled by the active lashing of countless
cilia which are microscopic whips, especially numerous on the gills of
the bivalve.

SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

1

From Johnson and Snook: Seashore Animals of the
Coast. Courtpsy of The Macmlllan Company.

Figure 4. Inside of right valve of Pismo clam
Dorsal side is shoAvn at the upper edge, ven-
tral is at the lower edge, anterior on your left,
and posterior on your right. Length is extent
from side to side and height is extent from lowest
to highest point in this figure.

1. Umbo <>• Anterior lateral tooth

2. Cartilage T. Anterior muscle scar

3. Ligament. <^. Posterior muscle scar

4. Posterior lateral tooth 9. Pallial sinus

r». Cardinal teeth 10. Pallial line ^j-^

, I

From Johnson and Snook: Seashore
Animals of the Pacific Coast. Courtesy of
The Macmlllan Company.

Figures. A Hard-shell Cockle,
Chione californiensis, view of
the anterior end

1. External ligament of hinge.
2. Umbo. '-5. Lunule. 4 Tiines
of growth.

Diameter is extent from left
to right in this figure

-t \

From Johnson and Snook: Seashore Animals of
Pacific Coast. Courtesy of The Macmlllan Company,

Figure 6. Diagram of a clam, Chione
undatclla, dissected to show the ar
rangement of the internal organs

AM. Anterior adduc- K. Kidney

ES.

F.
G.
H.

IS.

tor muscle

Excun'ent si-
phon

Foot

Gills

Heart

Intestine

Incurrent si-
phon

L. Liver

M. Mantle

P. Palps

PM. Posterior adduc

tor muscle
R. Rectum
RO. Reproductive

organs
S. Stomach

:1

\fter Birtscl (m difle 1 from i:)rew) '^nutl n in S(ie
.f.c Series.

Figure 7. The Razor clam uses its
foot in digging
Left, preparing to extend foot ; cen-
ter, foot extended and expanded; right,
anchored foot draws the animal down.

WEST COAST MARINE SHELLS 9

The cells of the mantle deposit shell-building material on the
inside of the shells making them thicker and at the free edges making
the shells larger. One can study the lines of growth and see the outline
of the shell when it was smaller. It will be seen that the shell, when
it was tiny, had the same proportions and general plan of structure
as the full-grown shell. Some clams are about the size of a small
pinhead when fully grown. The largest clam is Tridacna, found on
tiie Great Barrier Reef near Australia. This species may get to be a
yard long and may weigh 300 pounds.

Bivalves are to be found living in burrows in the mud, in sand, in
rock, or in wood; and one common bivalve, the scallop (Pecten)
swims in the water by clapping its shells together. Some scallops
attach themselves to seaweed. The common oyster attaches itself firmly
and permanently to rocks, shells, or piling. The mussel attaches to
rocks or piling by means of stiff, strong threads that it makes for itself.
^J'hese threads are known as the hyssus.

The shipworms, which are mollusks with long, wormlike bodies,
bore into wood. Their shells are small but so shaped that they can
rasp the wood and extend the burrow as needed. They do great
damage to wooden structures that are in the salt water. Wooden
ships suffered greatly from the destructiveness of these mollusks.

The eggs of bivalves are produced in great numbers. One oyster
may produce many millions of eggs. The eggs may be fertilized
within the mantle cavity of the parent and may develop there for a
time. They are usually' set free as larvae which first swim by means
of microscopic cilia and later live as their parents did in mud, sand, or
wood, on rocks, or swimming about in the water. The tiny rock-borers
make their way into minute holes or crevices in the rocks. As they grow
and move about they gradually wear the holes larger. Siphon tubes con-
nect them with the water and food outside so that they do not need to
leave their rocky prisons.

Bivalves, in many cases, are used extensively as food. Most of the
pearls come from bivalves, and are made of the same material that
lines the shells. If some foreign substance becomes lodged near the
shell producing cells of the mantle, it is likely to be covered with the
pearly deposit. If it becomes cemented to the shell, it forms a blister
pearl, if it is free from the shell it becomes a spherical or irregularly
shaped body, entirely coated with mother of pearl.

Following are brief descriptions of a few of the most common
bivalves. N., C, and S. indicate that the shell is to be found on the
beaches of northern, central, or southern California. Structures to
which reference is made, are indicated in Figures 4. f). and G. Shells
are not all drawn to the same scale.

10 SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

Native Oyster, Ostrea lurida. Irregular shape, sometimes circular and some-
times elongated. N.C.S. Height : may reach two inches and one-half.

Fan-shell or Circular Scallop, Pecten circularis. Nearly circular and the
diameter more tlian half the height. Strong, regular rihs radiate from the hinge.
C.S. Height: nearly two inches. The specklwl scallop, variety aequisulcatus is
flatter and larger. S. Height : may be three inches.

Rock Scallop or Purple- Hinged Scallop, Ilinnites giganteus. Small shells
free and regular, older ones attached to rocks and irregular in shape. Hinge area
on the inside tinged with puri)le. N.C.S. Heiglit : reaches three inches.

Sea Mussel, Mytilus oalifornianus. Attach^nl to the nx-ks where the surf Insits
over them. Brownish-black, conspicuous radiating ribs. Height : may reach eight
inches; four inches more usual. N.C.S.

Bay Mussel, Mytilus eduliK. Attached to wharf pilings. lirowni.sh-black
epidermis. Valves wider in proportion to length than in ^f. californianus. N.C.S.
Height : reaches two and one-half inches.

Capacious Horse-Mussel, Modiplus capax (also called Volsella capax) . Common
on stones, breakwaters, and on wharf piles in bays and estuaries. Where periostracum is
removed, shell may be brick red. Height: about three inches. S.

Straight Horse-Mussel, Modiolus rectus (also called Volsella recta). Long, nar-
row, often bearded, brown. C.S. Height: reaches six inches.

"Rock-eating" Mussel, Jjithophaga plumula. In rock burrows, cylindrical
shell, slender. C.S. Height : about three inches.

Agate Chama, Chama pellucida. One valve solidly attached to support,
strong, rough, with translucent, concentric frills, white or tinged with red. Illus-
tration shows interior view of the upper valve. N.(\S. Height: about one inch.

Cockle or Heart-shell, Cardium nuttallii. Found on tide-flats, more abundant in
north. Conspicuous ridges (roughened but not spiny) radiate from umbo, ridges and
grooves of the two valves interlock at the margin. N.C.S. Height: about two and one-
half inches.

Pismo Clam, Tivela stuUorum. Shell thick, heavy, light-colored, sometimes
with radiating lines of brown. Glossy periostracum. ('.S. Length : up to .seven
inches or more.

Sea Cockle, Amiantis callosa. Heavy, pure white, gh)ssy shell with prom-
inent concentric ridges. S. Lejigth : up to four inches.

Washington or Butter Clam, Soj-idomus nuttaUi . Heavy shell with prom-
inent ridges, white inside with purple marks near j)osterior end, usually light brown
or dull white; deep pallial sinus. N.C.S. Length: to five inches. *V. giganteus
known by the same common names, is more nearly circular with finer and less
prominent ridges, no purple markings within. N.C. Length : about three inches.

Hard-shell Cockles, Chione fluctifraga, and C. californiensis. Found in bays, in
mud or sand; rounded, heavy shells. S. Length: two or two and one-half inches. Chione
fluctifraga: (Fig. 8) no distinct lunule, radiating ribs more pronounced than the con-
centric lines of growth. C. californiensis: (Fig. 5) conspicuous lunule, concentric ribs
few and more conspicuous than radiating ribs.

Rock Cockle, Protothaca staminea (formerly called Venerupis or Paphia staminea) .
Radiating ribs are even and more conspicuous than the lines of growth, margins of valves
on inside joughened with fine teeth. N.C.S. Length: reaches three inches.

WEST COAST MARINE SHELLS

11

Washington or Butter C lain Sea Cockle

Figure 8. Croup of Common Bivalve Shells (continued on next page)

12 SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

Bodega Tellen, Tellina hodegensLt. Long, flat, white, polished, marked with
fine, regular lines of growth. N.C.S. Length: two inches or more.

Bent- nosed Clam, Macoma nasuta. Shells thin, flattened, white, with con-
spicuous ligament, posterior end narrow and bent to right. Found in muddy bays.
N.C.S. Length : about two inches.

White, Sand Clam, Macoma aecta. Shells thin, white, with faint growth
lines, ligament conspicuous. Left valve flatter than right. N.C.S. Length:
reaches four inches.

Sunset shell, Gari californica. White, margin with brown periostracum, red rays
radiate from umbo to margin, faint, red, concentric lines. N.C.S. Length: to four inches.

Purple Clam, Sanguinolaria nuttalli. Appears to be covered with brown
varnish, below this, shell is tinged with purple; thin, flat; right valve flattened
more than left. C.S. Length : three inches or more.

Wedge-shell, Donax calif ornicus. Small, smooth, with fine radiating and concentric
lines. Margin edged inside with fine teeth. Hinge near middle. C.S. Length: reaches
one inch.

Bean-Clam, Donax gouldii. On ^andy ocean beaches; fine radiating and
concentric lines, often beautifully marked with radiating patterns of darker color.
Wide variation in the colors. Margin within bears fine teeth. C.S. Length :
usually three-fourths inch.

Jackknife Clam, Tagelus californianus. Length : three or more times height,
hinge central, shell thin, light-colored, often covered with brown periostracum. C.S.
Length : three or four inches.

Jackknife Clam, Solen su-ariua. Hinge near anterior end, shells thin with
yellowish periostracum. N.C.S. Length : three inches. ;Sf. rosaceus, also a jackknife
clam is similar but smaller, more slender, and its rosy color often shows through
the thin periostracum. S. Length : between two and three inches.

Ra«or or Sea Clam, SiUqtw, pntula and /Si. lucida. Shells thin, tinged with
violet ; a prominent rib extends from the hinge across the inside of each valve. In
S. patula the rib is broad and oblique. N.C. Length: five or six inches. In S. lucida the
rib is narrow and nearly perpendicular to the margin. C.S. Length: one and one-half
inches.

Gaper, Schisothaerus nuttalli. Shells gape where siphons enter, siphons
cannot be withdrawn between the valves. Shell white with brown periostracum. N.C.S.
Length: reaches eight inches.

Soft-shell Clam, Mya arenaria. Whitish, with darker periostracum, carti-
lage pit of left valve on a conspicuous spoonlike tooth. N.C. Length : reaches
five inches.

Rock Clam, Platyodon cancellatus. White or gray; fine, regular lines of growth;
hinge nearer the posterior end of shell; spoonlike tooth in le(t valve; valves markedly
arched. C.S. Length: reaches two and one-half inches.

Geoduck (pronounced goiduck), Panope generoaa. Liues of growth distinct,
valves can not be completely closed, left valve has a small, sharp hinge tooth.
N.C.S. Length : reaches seven inches.

WEST COAST MARINE SHELLS

13

Geoduck

Rock Clam

Figure 8. Group of Common Bivalve Shells (continued)

14

SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

Rough Piddock, Zirfara piltihryi (formerly Z. pahhi). Found in burrows in
clay; the liujje siplion can not be withdrawn between the shells; shells gape widely
at both ends, N.C.S. Length : reaches four and one-half inches.

Piddock, Parapholas calijomica. Anterior end rounded, rough, posterior end smaller
and covered with scaly periostracum, two long narrow plates over hinge region. N.C.S.
Length: reaches three inches.

Rock-boring Clam, Pholadidea penita. Anterior end rounded, posterior narrower
and with scaly periostracum. Triangular plate over hinge area. N.C.S. Length: reaches
three inches.

Shipworms, IhnikUi sctnrnt ( illus(rat«Ml ) . Teredo novalis, and Teredo dieyev-
.s/.s. These are three of tlie species of shipworms that byrrow into wharf piling and
other submergefl wooded structures. The shells are much shortened and gape
widely. The bo<ly of the siiipworm is long and covered by the mantle which secretes
the small pair of shells at the anterior end, the shell material that lines the burrow,
and a pair of oarlike pallets that may close the burrow in the rear. The pallets of
Bankia suggest a series of small coups and those of Teredo aie shaped like paddles.

Rock-boring Clam

Rough Piddock

Shipworm
Piddock
Figure 8, Group of Common Bivalve Shells (continued)

WEST COAST MARINE SHELLS 15

TOOTH SHELLS (Scaphopoda)

Tooth shells are shaped like miniature elephant tusks. The shells
are hollow and open at both ends. The living mollusks are to be found
partly buried in the sand below the low-tide line. Both the head and
the foot of the animal are at the large end of the shell. The foot can
be extended and is used to burrow into the mud. A number of cap-
tacida, like small threads, extend out into the mud and capture tiny
animals for food. This food is carried to the mouth and is broken up
by the fine teeth of the radula. As the animal grows, it builds on to
the shell at the large end.

Empty shells are sometimes washed on the beach in great numbers,
but there seem now to be comparatively few beaches along the Cali-
fornia coast where they are likely to be found. The Indians used
these shells for ornaments, and also strung them and used them as
money.

The Hexat^fonal Tooth shell, Dentalium neohexagonum is slen-
der and slightly curved. Six rounded, longitudinal ribs extend
the length of the shell. Because of the six ribs, the aperture (large
opening) and apex (small opening) of the shell
are hexagonal even though the ribs may be
much worn. Usually a little less than an inch
and a half in length. Found from Monterey

Hcx.igonal Tooth Shell

to Central America.

SNAIL-LIKE SHELLS

(Gastropoda)

The univalves or shells that are built all in one piece are usually
coiled. The coiling shows great variety, giving long turret sheUs, fat
m.oon snails, irregular wormlike tubes (Figure 9), abalone shells,
limpets (Figure 10), and many other kinds. Some of the gastropods
are like the garden slug in having no external shell. Some of the
kinds that appear to have none do have an internal shell which is of
little or no value as a protection to the owner.

Shells of the univalve type vary in size from little ones that are
mere specks to giants two feet long. The abalone shells are among the
largest found on the California coast. Some of these may reach nine
inches in length. Look for the extremely small kinds of shells among
the broken pieces that collect in tide pools or between the rocks. If
one brings home a few quarts of this shell mixture and looks it over at
home he can often find many small, perfect shells.

16 SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

In most of the gastropods, the large muscular foot and much of the
soft body of the moUusk emerge from the shell when the animal is
feeding or moving about and the shell is borne aloft on the animal's
back. A part of the body always remains attached within the shell
and tlie animal can quickly retreat to its protecting cover.

When the mollusk body is fully retracted, one may find that a
horny or hard trapdoor (operculum) blocks the aperture of the shell
and protects the owner from enemies. When the animal is moving
about, the operculum may be seen, attached near the hind part of the
foot (Figure 11) at just tlie right point to bring it into place in the
doorway of the shell when the foot has retracted completely. Some
of the gastropods are not provided with the operculum and many of
them in hot, dry weather keep from drying up by secreting a film of
slime which seals the aperture effectively. One often finds garden
snails attached to boards or leaves by the film of slime that has
hardened around the edge of the shell aperture. In wet weather, the
snail may break the seal and become active.

A gastropod is usually provided with a radula for rasping its
food into bits (Figure 1). The action of the radula is more like that
of a file than like the biting of a pair of jaws. Some of the gastropods
also have jaws with which they can bite off their food. Carnivorous
species usually have fewer and more powerful teeth than vegetarians
have. The Oyster Drill is one of the carnivores and uses its radula
to drill a hole through the oyster shell ; it then inserts its proboscis and
and devours its helpless victim. The neat, round hole made by the
gastropod drill may often be seen in an empty shell and tells how
the owner of the shell came to die.

The ''Tyrian Purple" with which the ancient kingly robes were
dyed, was produced by mollusks. The sea hare, a mollusk, of our coast
gives off a purple fluid as a smoke screen when it is disturbed. As dyes,
these colors are inferior to the ones that modern chemists have produced.

Following are brief descriptions of a few of the most common gastro-
pods. Structures, to which reference is made in the descriptions, are
named and located in Figure 12. N., C, and S. indicate whether the
species is to be found on the north, central, or southern California
beaches.

WEST ("OAST MARINE SHELLS

T7

•6

m m

Figure 9. Scaly Worm-shell, Aleles
squamipcrus, on a rock at the shore

'i'lip niolhisk sIipUs arp tho larf,'Hr oiios
which .sliow loiijjitiulinal and circular
ridjjcs. The small coilpd shells are those
of worms.

I'rom Johnson and Snook: Seashore Animals of tli(
I'acifle t'oHst. Courtesy of The Macmillan Company.

Figure 11. Carpenter's Turret as it
appears when fully extended
1. Oi>erculum 4. Eye

-• Foot 5. Siphon

3. Tentacle

Figure 10. Three living limpets on a
rock at the shore, Acmaea persona

From Johnfon and Snook: Seashore Animals of the
Pacific Coast. Courtesy of The Macmillan Company.

Figure 12. The Frog-shell, Bursa cali-
forniva

7. Anterior canal

1. Apex

2. Spire

3. Body whorl

4. Suture

5. Posterior canal

6. Outer lip

S. Columella
9. Aperture

10. Varix (plural,

varices)

11. Umbilicus

18 SCIENCE CIUIDE FOR ELEMENTARY SCHOOLS

Cloudy BubbTe, Bulla gouldiana. Gray or reddish, often mottled, compara-
tively thin. Mud flats. S. Length : two inches or more.

Green Bubble, Ilaminoca rirescens (illustrated). Thin, aperture markedly
wider below. Mossy rocks. S. Length : less than one-half inch. White Bubhle,
Jfaminoea vexiruJa. Similar but slightly larger, aperture less flaring below. Mud
flat.s. N.C.S.

Olive Ear-shell, Mehmptix olimreus. Hrown, marked with lighter bands,
two folds on the columella. Mud flats, abundant. Length: one-half inch. ('.S,

Netted Button, Trimusculus reticulata (formerly called Gadinia) . White, low
arch, blunt apex, fine radiating ridges crossed by lines of growth. Diameter: one-half
inch. N.C.S.

California Cone, ('onus cafiforxirns. Shell of living moUusk covered by
brown ei>idennis. worn shells chestnut color and porcelainlike. Length: usually
under one inch. C.S.

Purple Olive, Olivella biplirafa. Thick, heavy shell, gray, shaded with
j)urple or brown. Columella white with two folds at the base. Length: less than
one inch. N.C.S. Sandy, ocean beaches.

Pear-shaped Marginella, Cifpraeolina pyriformxs. I'ure white, polished sur-
face. Length : one-eighth inch N.C.S.

Wheat-shell, Marginella ralifornica. Size and color of a grain of wheat.
Four folds on the columella. Shining surface. S.

Kellett's Whelk, Kelletia kelleti. Large, heavy, with prominent nodes on the whorls.
Length: up to three inches. S.

Livid Macron, Macron lividas. Shell of living mollusk covered with brown epi-
dermis, worn shells light brown, smooth. Length: one inch or less. C.S. Rocky beaches.

Dire Whelk, Searlesia dira. Brown spiral lines, with ashy channels between. N.C.
Length: one and one-half inches.

Channeled Basket-shell, Nassarius jossatus. Brown or orange markings on a
lighter ground. N.C.S. Length: one and one-half inches.

Fat Basket-shell, Nassarius perpinguis. Spiral and longitudinal lines cut
the surface into uniform squares. N.C.S. Length : to one inch.

Covered- lip Basket-shell, Nassarius tegula. Stout, white callus over front
of ishell and inner lip. Gray or brown. C.S. Length : five-eighths inch.

WEST COAST MARINE SHELLS

19

Livid Macron
Figure 13. Group of Gastropod Shells

Fat Basket-shell

20 SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

Dove-shell, MitrcUa carinaia. Brown, glistening, whitish keel at the upper
boundary of the body whorl. C.S. M. gausapata: similar to M. carinata but no keel.
Length: one-fourth inch.

Festive Rock-shell, Pterynotus festivus. Each whorl has three backward-turning
varices with a prominent, rounded knob midway between two frills. Marked with fine
spiral lines. Canal closed to form a tube, bent back at the tip. Length: an inch and one-
half or more. S.

Leafy Horn-mout-h, Ceratostoma foliata (also called Purpura). Three prominent
varices. Prominent spiral ridges spread out fanlike on the varices. Inconspicuous knob
on spirals between two varices. Closed canal turned back at the tip. Margin of aperture
wavy, with a sharp horn below. N.C.S. Length: three inches or more.

Nuttall's Horn-mouth, Ceratostoma nuttalli (also called Purpura). Three knobs
and three varices about equal in size on each whorL Varices not rolled backward. Teeth
inside of lip corresponding to the spiral ribs on the body whorl. Sharp horn at base of
lip sometimes absent. Canal closed or open. Brown, white in aperture. Length: up to
two inches. S.

Poulson's Rock-shell, Ocenebra poulsoni. Varices are prominent, rounded ridges
on the central and lower part of each whorl. Fine spiral lines encircle all the whorls.
Five or six rounded teeth in outer lip. Length: two or three inches. S.

Wrinkled Purple, Thais lamellosa. Dirty white or banded with brown.
Strong, heavy shell. A number of varieties are known, some more frilled than
shown in the figure and some smooth. Length : two or three inches. N.C.

Rock-dwelling Thais, Thais cmarginata. Shell rough, with rough knobs on
some of the more prominent spirals. Wide, rounded aperture. Hough and smooth
varieties have been described. Length : usually under an inch and one-half.
N.C.S.

Angled Unicorn, Acanthina spirata. Clings to rocks. Small horn at base of
outer lip. Distinct angle below the suture. Dark, broken, spiral bands giving a
si>eekled pattern. Ten or twelve white spirals on the body whorl. Length : one
inch and one-quarter or less. N.C.S.

Square-spotted Unicorn, Acanthina paucilirata. Like A. spirata but with
three or four spiral white lines on the body whorl. Narrow white spirals alternate
with wide black bands broken into black squares. Length : about three-fourths of
an inch. S.

White Wentle-trap, Epitonium tinctum. White, rounded whorls, each
crossed by 11 to 14 sharp, thin ridges. Ridges may be turned backward slightly
with a sharp keel near the suture. Length : one inch or less. C.S.

Nut-brown Cowry, Cypraea spadicea. Brown above and white below.
Spire covered by newer parts of the shell. The red mantle of the living animal
almost covers the shell. Length : up to two inches. C.S.

Large Coffee -bean, Trivial solandri. Ranges from brown to pink. Low
ridges run around the shell ending in white knobs above and teeth on the outer
lip. Length : under three-quarters of an inch. S.

WEST COAST MARINE SHELLS

21

Festive Rock-shell

Poulson's Rock-shell

White Wcntle-trap

Anf^ltd Unicorn

Square-spotted

Unicorn

Niittuli's Horn-mouth

Dove- shell

Larije Coffee-bean
Figure 13. Group of Gastropod Shells (continued)

22 SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

Small Coffee-bean, Trivia californiana. Like T. solandri but smaller and darker
colored. Both shells are rounded above, and flattened below. Length: less than one-half
inch. N.C.S.

Apple-seed, Erato vitellina. Pear-shaped, reddish brown, white along the
toothed-aperture. Length : half an inch. C.S.

California Frog-shell, Bursa coUfoniica. Strong shell, with prominent length-
wise ridges and conical knobs. White within. Length : usually three inches but
may be larger. C.S. Fig. 12.

Oregon Triton, Fusitriton oregonensis (formerly called Argobuccinum) . Regular
longitudinal and spiral ridges. Dark, hairy epidermis in strong contrast to the glisten-
ing, white interior. Length: four inches. N.C.S.

Scaly Worm-shell, Aletes squamigerus (Fig. 9). Irregularly coiled shells fastened
to rocks or to other shells. Distinct ridges run lengthwise and circular lines or growth
show clearly. Circular aperture one-fourth inch in diameter or a little more. C.S.

California Horn-shell, Cerithidea californica. Dark l)ro\vn or black. The
ribs and ridges variable in size. Found on mud flats in great numbers. liengdi :
an inch or more. C.S.

Gray Littorine, Littorina platiaxis. Broad shells with only faint spirals or
lines of growtii. Inner lip flattened, outer lip thin. Length: a little over one-half
inch. N.C.S. Checkered Ijitlorino, Jj. scutulata, is more slender, with checks or
bands of white and without the flattened lip. N.C.S.

Ancient Hoof-shell, Ifipponix antiquatns. Obliquely flattened cone, lives
attached to locks. Surface rougliened by raised concentric lines of giowth. length:
about one-half inch. N.C.S.

Sculptured Hoof -shell, Hipponix tinneus. C/ap-shaped with the apex curved
over. Stirface with even, radial and concentric ridges. Length: not over tliree-
(piarters of an incii. N.C.S.

Onyx Slipper, Crepidula onyx. Dark brown with white deck. Apex at
m:irgin of the shell, turned to one side. liCngtli : reaches two inches. C.S.

Hooked Slipper, Crepidula udunca. Brown with white deck. Height nearly
two-thirds the diameter with apex reaching beyond margin. liength : one-half
inch or more. N.C.S.

Wrinkled Slipper, (Jrepidula lingulata. Rounded, flat, with free apex near
the margin. Radiating furrows near the margin give surface a wrinkled appear-
ance. Deck with ridge in the middle and partly detached from the left side.
I^ength: about one-half inch. N.C.S.

Cup-and- Saucer Limpet, Crucibuluni spinosum. High-arched or more flat-
tened, spiny or nearly smooth, apex nearly central, cup roughly triangular and
nearly white. Length: about one inch. N.C.S.

WEST COAST MARINE SHELLS

23

Onyx Slipper

California Horn-shell

Small Coffee-bean

Applc-seccI

Gray Littorinc

Ancient Hoof-shell

Oregon Triton

Hooked Slipper

Sculptured Hoof-shell Wrinkled Slipper Cup-and-Snucf r I.rmpet

Figure 13. Group of Gastropod Shells (continued)

24 SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

Lewis Moon-snail, Polinices lewisii. Large, heavy shell, yellowish white,
nearly smooth. Umbilicus is open, the patch of enamel on the columella overhangs
umbilicus little or not at all. Height : about four inches or more. Height greater
than the diameter. N.C.S. El Draco's Moon-snail, P. draconis. Like P. lewisii but
diameter greater than height. Each whorl more rounded. N.C.S.

Southern Moon-snail, Polinices reclusianus. Flattened spire, umbilicus nearly or
quite covered with the enamel patch. Height: an inch and one-half or more. S.

White Cap, Acmaea mitra. Heavy, conical, white shell, aperture nearly cir-
cular, apex nearly in the center. Length : an inch or more. N.C.S.

Plate Limpet, Acmaea patina (sometimes called A. scutum). Large shell with
rounded apex near the center. May have a pattern of black radiating or broken lines.
Threadlike ribs, with inter-spaces wider than ribs, or surface worn smooth. Inside is an
irregular central area of brown and a dark border at the margin. Length: about an inch
and one-half. N.C.S.

Shield Limpet, Acmaea pelta (sometimes called A. cassis). Strong, heavy shell,
high apex, near the center, large rough ribs. Inner margin has a black border or a series
of scallops between ends of ribs. Central brown spot inside small or absent. Radiating
ribs sometimes lost. Length: about an inch and one-half. N.C.S.

Mask Limpet, Acmaea persona. Apex pointing forward. Numerous, tine,
threadlike, radiating ribs. Large, central, brown area, usually present. Length :
lip to two inches. N.C.S.

Fingered Limpet, Acmaea digitalis. Outer surface coarse, usually with rough
ribs which are larger near the margin. Apex almost directly above the anterior
margin or overhanging it. Inner surface with elongate, dark, brown spot in ap4>x
and dark border. I^ength : up to one inch. N.C.S.

Ribbed Limpet, Acmaea scabra. Conspicuous ridges giving the margin a
very irregular outline. Length : may be a little over an inch. N.C.S.

File Limpet, Acmaea limatulu. Low arch and outline like .4. scutum but
surface with radiating, beaded ridges, yellowisli brown. licngth : an inch and
one-half. N.C.S.

Owl-shell, Lottia gigantea. Outer surface rough, inner dark with a bluish
center sometimes marked with brown. Arch low and apex near end. F-iength :
usually two inches but may reach three and one-half. N.C.S.

Wavy top, Astraea undosa. Large shell. Prominent spiral ridge just above
suture. Pearly under the brown periostracum. Operculum heavy, thick, with
two curved ribs on outside. S. Length : up to six inches. Red Top, Astraea in-
aequaUs, is similar but the spiral ridge above the suture is less prominent and the
operculum lacks the curved ribs. N.C.S. Length: up to two and one-half inches.

•Smooth Turban, Norrisia norrisii. Brown shading to black near the deep
umbilicus which is bright green. Body of the living mollusk is red. Reaches
nearly two inches in diameter. C.S.

WEST COAST MARINE SHELLS

25

Owl-shell
Figure 13. Group of Gastropod Shells (continued)

26

SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

Black Turban, Tegula funehralis. Nearly smooth, black, pearly within, um-
bilicus nearly closed. A variety has prominent spiral ridges. N.C.S. Diameter
may reach one inch.

Gilded Turban, Tegula aureotincta. Spiral and cross ridges, gray, umbilicus
stained bright yellow. S. Diameter may reach one inch.

Blue Tap, Calliostoma ligatum (formerly called C. costatum) . Brown, bluish when
wave-worn, strong, with even, smooth, spiral ribs. N.C.S. Diameter a little less than
one inch.

Ringed Top, CaUiostoma annulaium. Beaded, spiral ridges, shell thin, straw
color with purple band at the sutures, at the angle of the body whorl and at the
columella. N.C.S. Diameter: reaches one inch.

Channeled Top, CaUioatoma ranalicnJatinn. Ligljt brown with conspicuous
whitish spiral ridges with little, if any, bending. N.C.S. Diameter : may be
slightly over one inch.

Black abalone, IlaUoiia crarheiodii. Greenish black with high arcii, outside
is smooth except for the lines of growth. No conspicuous ridges at the line of holes.
Silvery red and green within. Five to eight open holes. N.C.S. Length: may
reach six inches.

Red Abalone, Haliotis rufescens. Relatively low arch, outside with low
irregular radijitiiig waves, holes tubular, large, three or four open. C.S. Length:
reaches nine inches.

Volcano-shell, Fissurella volcano. Oval, narrower in front, "Keyhole" oblong
and n*'}ir the center. Reddish to brown. N.C'.S. Length: reaches one inch.

Giant Keyhole Limpet, Megathura cienidata. Gray with fine, even, radiat-
ing ridges crossed by lines of growth. In life, the black mantle of the animal
nearly covers the shell. S. liength : four inches or more.

Rough Keyhole Limpet, Diodora aspera. High-arched, nearly circular hole. Promi-
nent radiating ridges. N.C.S. Length: reaches two inches.

\'ol*..ino-shcll

Red Abal<

Rough Keyhole gj.,^.,, j^, ,[,.,„

Limpet Channeled Top

Figure 13. Group of Gastropod Shells (continued)

Gi.int Keyhole
Limpet

WEST COAST MARINE SHELLS 27

NAUTILUS SHELLS (Cephalopoda)

The Nautilus is the only recent cephalopod that has much of a
shell. The Pearly Nautilus which is found near the shores of the
South Pacific and Indian Ocean has a large shell that is coiled
symmetrically (Figure 14). It also differs from the gastropod shelJs
in that its interior is divided into a series of chambers by partitions or
septae. As the animal grows, it walls off the old part except for a
small opening through which a slender strand of body tissue extends
to connect with the first sm-all chamber at the beginning of the spiral.

higure 14. Nautilus and huge fossil ammonite

The smaller shells are those of the Pearly Nautilus.
Xautilus pompilius. One of the specimens is cut in half
(o show tiie partitions. The lurj?e fossil ammonite Avas
collected by Charles II. Steinberg near Catarina, Lower
California. This specimen is seventeen inches across.

Thus it occupies the outermost chamber in the largest part of the coil.
The Nautilus animal looks somewhat like our squid, octopus ( Figure 15 ) ,
cuttlefish, or Paper Nautilus, but these others have very different shells
or none at all. The cuttlefish have internal limy shells that we know as
cuttlebone. The squid's shell is called a pen, being thin and straight and
of chitinous material (Figure 16). One fi^ds no shell in the octopus.

The Paper Nautilus is sometimes found off the west coast. The
female of this species produces a spiral shell in which she carries her
eggs. This shell is only an egg ca.se which can be left by the owner at
will and is quite different from the shell of the Pearly Nautilus which
is a permanent home to which its owner is firmly fastened.

28

SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

From Johnson and Snook ; Seasliorc Animals of the Pacific Coast. Cour-
s.v of The Macmillan Company.

Figure 1 5. An Octopus, Octopus bimaculatus, small
specimen, drawn from life

portions
Of shelf
A B C 0 E F

.After Bartsrh from Smithsonian Scientific Series, by permission.
Figure 16. Internal shells of cephalopods

A. Pen of n bcloninoid. a fossil cephalopod ;
li, (\ I>. Pons of squid ;

E. Ciittlofish with mantlo roinoved to show shell ;

F. Coiled shell of Spirula, a cephalopod.

Although the cephalopods of this coast now provide the collector
with little interesting shell material, there was a time many thousands
of years ago when huge cephalopods lived here. Fossil shells of
ammonites (relatives of the Nautilus) have been found in southern and
Lower California that are more than a foot across ( Figure 14) . For some
reason these ammonites died out so that they are known now only as in-
teresting fossils.

WEST COAST MARINE SHELLS 29

SUGGESTIONS FOR PUPIL ACTIVITIES

COLLECTING SPECIMENS

The children should all have the fun of finding shells and living
mollusks at the beaches. Whether they care to keep the collections or
jiot, they can learn much from a beach excursion. If possible, trips
should be made to sandy, rocky, and muddy beaches. This will make
clear the fact that different animals are adapted to life in different
situations and are dependent on certain food supplies. If the teacher
can take all or a part of her class to the beach, she should first study
the tide table and choose a day and hour when the tide will be low.
It is better to be at the shore at least an hour before the tide is lowest
so that one can do most of the collecting while the tide is going out.
An incoming tide on some of the beaches makes the collecting hazardous
if the children are too venturesome.

PREPARING SPECIMENS

Great numbers of empty shells may be picked up at the beaches
but many of them are so worn and broken that only an expert can
identify them. Among the broken shells will be some that are nearly
perfect. This is the only way that one is likely to come into posses-
sion of the shells of some animals that live far out in the deep water
unless one has at his command a deep-sea dredging outfit. These
ready cleaned shells can go into the collection without special prepa-
ration, but the ones tliat contain tlie living or recently dead animals
must be cleaned. The easiest way to free the animal tissue from the
shell is to boil the mollusks for a short time. Large sliells thrown into
boiling water may crack ; so it is better to heat tliem slowly. After
boiling, remove the body of the snail by means of forceps, or a bent
pin, or wire. If the collector thinks that there may be a little of tlie
animal left in the tip of the shell, he should soak cotton in alcohol
(70 or 80 i)er cent) or formaldehyde (5 per cent) and stuff it into
the spire, then fill the rest of the shell with cotton. If the mollusk
has an operculum, it should be glued to this cotton. The collector
should always save the operculum and if he is making a scientific
collection the radula should be placed in a small bottle of 80 per
cent alcohol. The label on the bottle should correspond with the shell
label. The information on the label should include the scientific name
of the specimen, the place where it is found, the date when taken,
and the collector's name.

30 SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

Chitons may be dried whole or cleaned as one prefers. One can
tie them tightly to a lath or small board before they be«>in to curl
out of shape. After the animal is dead it can either be removed from
the shell or dried until there is no odor from it. Some collectors pre-
fer to put chitons in a jar or pail of sea water. After they have all
attached firmly to the sides of the container, the watei- may be ])()iire(i
out and the animals will remain attaclied and dry flat.

CONSERVING SHORE ANIMALS

Pupils should be taught to select their- specimens carefully at the
beach, not destroying or taking awa.N' more than they have use for.
Even the apparently endless supply of shore animals can be depleted.
Species vary in abundance from year to year. Sometimes the Donax
clams, for instance, are very abundant and then suddenly there are
few of them to be found. Shifting tides and currents, food supply, para-
sites, temperature, perhaps other factors are responsible for their appear-
ance and disappearance. In some cases, as perhaps in this instance, man's
greed in taking great numbers of clams probably has little to do with their
disappearance; but in many cases overfishing has depleted the numbers;
consequently the restrictions outlined in the state fish and game laws are
very necessary and should be carefully heeded.

The teacher should get a current copy of the fish and game laws for
his seotion of the coast and should know what species and how many of
them can be taken. This is a good opportunity to teach law observance
along with nature study. Closed seasons are often prescribed during the
reproductive season of the animals.

POISONOUS CLAMS AND MUSSELS
Mussels and clams on some parts of the coast are poisonous and not
fit for food during certain months of the year so they are quarantined dur-
ing that time. The California State or local Department of Public Health
can furnish up-to-date information on this point. The quarantine dates
are not always the same from year to year but are determined by the re-
sults of weekly examinations of the shellfish.

ACTIVITIES FOR LOWER-GRADE PUPILS

1. Study the garden slugs and snails kept in the terrarium. Have
pupils oft'er the animals various kinds of food to tiiid what the mol-
lusks will eat.

2. Watch the pond snails in the aquarium. They can usually be
seen at work scraping the algae from the glass sides of the aquarium.

3. Study the feeding habits of clams. Most of the marine clams,
if covered with clean sea water and left undisturbed for at time, will

WEST COAST MARINE SHELLS 31

extend the siphons and demonstrate the water currents flowing in and
out by way of the tubes.

4. Watch the living scallops (Pecten) . These animals will usually
expand in clean sea water so that the mantle edges and numerous tiny,
jewel-like eyes are clearly visible as the shells gape.

5. Study a variety of living gastropods. Have pupils notice how
the operculum is carried when the animals travels and how the aper-
ture of the shell is closed by the operculum when the animal withdraws
into the shell.

6. Make collections of shells in the vicinity. A convenient way
for children to arrange their collections is to put them in Riker Mounts
or similar, homemade, glass-topped boxes. These can be purchased of
the supply houses or made by cutting out most of the top from the
cover of a strong, sliallow cardboard box and replacing the cut-out
area with glass or cellophane bound to the cover with paper, cloth, or
cellulose tape. A thick, smooth bed of cotton should keep the shells in
place. If the cover is bound with black tape, before the glass or
cellophane is attached, the box will be stronger and look better.

7. Learn songs and poems about sea life.

8. Make booklets of poems and stories illustrated by original
drawings.

ACTIVITIES FOR UPPER-GRADE PUPILS

1. Observe and collect material as suggested for lower-grade pupils.

2. Experiment with a snail. Have the pupils study the muscle
action in the foot of a snail by allowing it to crawl on a clean piece of
glass. The underside of the foot can be seen through the glass.

3. Dig for specimens at the beach. Have older pupils dig for clams,
or break up the sandstone to find rock-burrowing worms and clams,
or locate shipworm burrows in water-soaked wood.

4. Devise games for the study of shells. A game similar to a
spelling down match may be arranged by using the names of the shells
that have been studied. The person or side naming the most shells
correctly wins. Also a game that requires observation and an effort
at accurate description may be played. One child selects a shell and
describes its form as clearly as possible without telling the name. A
good description is one that enables the class to recognize the shell
quickly. The child who describes best and the one who names the
shells first would together win the game.

32 SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

5. Learn the poem "The Chambered Nautilus" by Oliver Wendell
Holmes for concert or individual recitation.

6. Learn the fish and game laws pertaining to the taking of clams,
mussels and other shore animals.

7. Keep notebooks. Have pupil arrange a notebook of his own
observations and illustrated with his own sketches or with pictures
found in magazines.

8. Make a map of the nearest beaches to show where certain aui
inals of the shore are found in abundance.

9. Collect poems about sea life.

10. Find songs and pictures that correlate with the topic.

11. Read books on sea life.

WEST COAST MARINE SHELLS 33

GLOSSARY

Anterior end — The head end of an animal.

Aperture — The opening into a spiral, univalve shell.

Apex — The tip of a spiral shell.

Bearded — More or less covered with soft hairlike spines.

Bivalve — Shell consisting of two parts or valves, or the mollusk that produces such

a shell.
Byssus — Tough threads produced by some bivalves and used to attach the animal

to a rock or other support.
Cilia — Microscopic, whip-like projections from cells on surfaces of some animals.

These cilia by vibrating may produce a current of water through the animal

or if on the outside surface they may serve as swimming organs for the animal.

Columella — The central axis of a spiral shell.

Foot — Muscular organ for locomotion (Figures 6 and 11).

Gastropod — A mollusk belonging to the class Gastropoda, for example, a snail

(see pp. 15-26).
Girdle — The fold of integument which encircles and partly covers the chiton.
Larva — Early stages of certain animals which are free-living but have not yet

attained adult form.
Lunule — Sunken area in front of umbo in certain clamsi (Figure 5).
Mantle — Soft, outer sheet of tissue of mollusk body (Figure 11).
Nodes — Knobs or swellings.
Operculum — Cover or plate with which aperture of spiral shells may be closed

when the mollusk body is withdrawn into the shell.
Outer lip — In a spiral shell, the margin of the aperture farthest from the central

axis of the shell (Figure 12).
Periostracum-7-Outer layer of the mollusk shell.
Phylum — One of the chief divisions of the plant or animal kingdom; example

phylum Mollusca.

Proboscis — Tubular prolongation of mouth region in some gastrofwds.

Radula — Ribbonlike structure bearing rasping teeth, found in many gastropods and other
mollusks.

Siphons — Tubes of mollusks by which water is drawn in or ejected (Figure 6).
Suture — Line where two whorls of a spiral shell are joined (Figure 12).

Umbilicus — In gastropods, the pit at the base of the central axis of the shell
(Figure 12).

Umbo — (plumal, umbones) Knob on a clam shell just above the hinge (Figure 4).
Univalve — A mollusk shell that consists of one piece, or the mollusk that produces
this shell.

Valve — One of the separate parts of a mollusk shell.

Varices — (singular, varix) Ridges or frills across the whorls of a shell; they mark
successive points where the mollusk ceased growing for a period and built
additional material into what was tlien its outer lip.

34 SCIENCE GUIDE FOR ELEMENTARY SCHOOLS

BIBLIOGRAPHY

Arnold, Augusta Foot. The Seabeach at Ebb Tide. New York: The Century Company,
1901.

Well-illustrated account of Atlantic Coast seaweeds and invertebrate animals,

Bassler, R. S., Resser, C. E., Schmitt, W. L., Bartsch, P. Shelled Invertebrates.
Smithsonian Scientific Series, Vol. X. New York: Smithsonian Institution Series Inc.,
1931.

Part III of Vol. X of tliis series is on moUusks and written by Paul Bartsch. It is
an excellent and interestingly written general account of the mollusks.

BoNNOT, Paul. "Soft Shell Clam Beds in the Vicinity of San Francisco Bay." Cali-
fornia Fish and Game, 18, 64-66, 1932.

. "California Abalones." California Fish and Game, 26 (3), 200-211, 1940.

. "The Edible Bivalves of California." California Fish and Game, 26 (3), 212-39,

1940.

. "The Abalones of California." California Fish and Game, 34 (4), 141-69, 1948.

Cooke, Re\. A. H., and Others. Molluscs and Brachiopods. Cambridge Natural His-
tory, Vol. III. New York: The Macmillan Company, 1895.

A good reference for the teacher. Contains much general information on mollusks
of all kinds.

Crowder, William. Dwellers of the Sea and Shore. New York: The Macmillan Com-
pany, 1935.

Well-written description of habits of many of the common mollusks of the Atlantic
Coast.

Fitch, John E. "Common Marine Bivalves of California." Fish Bulletin No. 90, Cali-
fornia Fish and Game Commission, State Fisheries Laboratory, Marine Fisheries
Branch, Terminal Isl. Sta., San Pedro, Calif., 1953.

Sixty species of common bivalves illustrated and described. Range, habits, use, and
common and scientific names given. A useful key and many other helpful items included.

Gaylord, Ils^ien N. Little Sea Folk. Boston: Little, Brown, and Company, 1923.

A small book for children, describing seashore animals and their habits.

These stories were written for the Atlantic Coast but the general information is
equally applicable to Pacific Coast forms.

Guberlet, Muriel Lewin. Animals of the Seashore. Portland, Oregon: Metropolitan
Press, 1936.

Good photographs and descriptions of the Washington marine fauna. Particularly
helpful to those who collect on the northern beaches of California.

Johnson, Myrtle E., and Snook, Harry J. Seashore Animals of the Pacific Coast.
New York: The Macmillan Company, 1927.

One chapter on mollusks, with 314 black and white and 22 colored illustrations of
common mollusks of our coast.

WEST COAST MARINE SHELLS 35

Keen, A. Myra, and Frizzell, Don L. Illustrated Key to West North American Pelecypod
Genera. Stanford, Calif.: Stanford University Press, 1939.

Keen, A. Myra, and Pearson, John C. Illustrated Key to West North American Gastro-
pod Genera. Stanford, Calif.: Stanford University Press, 1952.

Keep, Josiah. Revised by Joshua L. Baily, Jr. W'est Coast Shells. Stanford, Calif.:
Stanford University Press, 1935.

The most complete small book on shells of the west coast, illustrated with line draw-
ings.

Kellogg, James L. The Shellfish Industries. New York: Henry Holt and Company, 1910.

A good book on the edible mollusks from the industrial standpoint.

KiNCAiD, Trevor. The Oyster Industry of Willapa Bay, Washington. The Tribune,
Ilwaco, Washington, 1951.

An account of the basic problems of planting, cultivating, and harvesting the oyster.
(For sale by Calliostoma Co., 1904 East 52nd St., Seattle, Washington. $1.00.)

Marcy, Clarence A. The Padre's Garden. San Francisco: Harr Wagner Publishing
Company, 1932.

A few stories on seashore collecting.

MacGinitie, G. E., and MacGinitie, Nettie. Natural History of the Marine Animals.
New York: McGraw-Hill Book Company, 1949.

This boolc has many original observations on the behavior and habitats of seashore
animals, especially those found near the KerckhofI Marine Laboratory near Newport
Bay.

Morris, Percy A. A Field Guide to Shells of the Pacific Coast and Hawaii. Boston:
Houghton-Mifflin Company, 1952.

Excellent illustrations, many in color.

Oldroyd, Ida S. The Marine Shells of the West Coast of North America. Vol. I, Vol. H,
Parts 1, 2, and 3. Stanford, Calif.: Stanford University Press, Vol. I, 1924, Vol. II, 1927.

Four good-sized volumes, well illustrated and giving more complete lists of species
and descriptions than the smaller books can give. For the advanced shell collector.

RiCKETTs, Edward F., and Calvin, Jack. Between Pacific Tides. 3d revised ed., revised by
Joel W. Hedgpeth. Stanford Calif.: Stanford University Press, 1952.

Deals with Pacific Coast animals and their habitats.

Rogers, Mrs. Julia Ellen. The Shell Book. New York: Doubleday, Page, and Com-
pany, 1908. Reprinted 1952 (with name changes in appendix).

Includes the more common shells from all parts of the world. Most of the species
mentioned are illustrated, some of them in color.

Smith, Jeanette. A Summer by the Sea. New York: American Book Company, 1935.

A well-written book for children. Includes other seashore animals as well as mol-
lusks.

Tryon, George W,, Jr., and Pilsbry, Henry A. Manual of Conchology. Philadelphia:
Academy of Natural Sciences. Marine Mollusks, Vols. 1-17, 1879-1898; Land Mol-
lusks. Vols. 1-28, 1885-1935.

The most complete and expensive work on shells. Sometimes available in city or
scientific libraries, and one which the serious collector will want to consult. New volumes
are still being published at intervals.

Verrill, a. Hyatt. Strange Sea Shells and Their Stories. Boston: L. C. Page and Com-
pany, 1936.

Much interesting general information on mollusks.

Weymouth, Frank W. The Edible Clams, Mussels and Scallops of California. Fish
Bulletin No. 4. State of California Fish and Game Commission. Sacramento: Cali-
fornia State Printing Ofl&ce, 1920.

Good pictures and descriptions of the edible bivalves. Very helpful in identifying
the clams that are found in the markets.

. The Life History and Growth of the Pisrno Clam. Fish Bulletin No. 7, State of

California Fish and Game Commission. Sacramento: California State Printing Office,
1920.

Technical paper telling about studies on rate of growth of these clams.

ADDITIONAL TITLES ON SHELLFISH POISONING

Curtis, Brian. "Mussel Poisoning Twenty-five Years Ago and Today." California Fish
and Game, 29 (3), 151, 1943.

. "Mussel Poisoning on the Pacific Coast." Nautilus, 57, 70, 1943.

A reprint of the above.

Meyer, K. F., and Sommer, H. "Mussel Poisoning." Calif, and Western Med., 42 (6) ,
423-26, 1935.

Sommer, Herman. "The Occurrence of the Paralytic Shell-fish Poison in the Common
Sand Crab." Science, 76, 574-75, 1932.

MBL WHOI Librai

5 WHSE 00004