s Eugene S. Clark, Jr. Cetological Research Laboratory Sandwich. Massachusetts JRIAT'S- BOOKS i1 Franklin Street Boston 7, Mass. GIANT FISHES, WHALES AND DOLPHINS a O < o c « S in A/p FIELD BOOK OF GIANT FISHES lv BY the late J. R. NORMAN, F.L.S. DEPARTMENT OF ZOOLOGY, BRITISH MUSEUM (NATURAL HISTORY) AND F. C. FRASER, D.Sc, F.L.S. DEPARTMENT OF ZOOLOGY, BRITISH MUSEUM (NATURAL HISTORY) With Eight Plates in Full Color and Over One Hundred Drawings by Lieut.-Colonel W. P. C. Tenison, D.S.O., F.L.S. K <+ G. P. PUTNAM'S SONS NEW YORK First published in nature field books . ig4g luced by photo-lithography by the Pitman Press, Bath, England CONTENTS Introduction xit PART 1 : FISHES. CHAPTER PAGE I. Sharks I II. Sharks (continued) ..... 27 III. Rays 56 IV. Soft-rayed Bony Fishes .... 86 V. Perch-like Fishes 114 VI. Perch-like Fishes (continued) . 141 VII. Barracudas, Remoras and Others . 160 VIII. Key to the Principal Fishes Described in this Book 188 PART II: CETACEANS. IX. Right Whales 203 X. 218 XI. Humpback Whale ; Californian Grey Whale 242 XII. Sperm Whales and Bottle-nosed or Beaked Whales 256 XIII. 283 XIV. Porpoises and Dolphins (continued) . 306 XV. Fresh-water Dolphins 338 XVI. Key to the Principal Cetaceans Described in the Book 344 Index 350 ILLUSTRATIONS i. Topography of a Fish ... . . 2. Topography of a Cetacean ..... 3. Flipper of a Sperm Whale ..... 4. Skull of a Whalebone Whale (Californian Grey Whale). 5. Skull of a Toothed Whale (False Killer Whale) . 6. Respiratory Organs in a Shark and a Bony Fish . 7. Six-gilled Shark or Griset (Hexanchus griseus) 8. Seven-gilled Shark or Perlon {Heptranchias perlo) 9. Sand Shark or Slender-toothed Shark (Odontaspis taunts) 10. Elfin or Goblin Shark (Scapanorhynchus owstoni) 1 1 . Common Porbeagle (Lamna cornubica) 12. Mediterranean Mackerel Shark {Lamna oxyrhynchus) . 13. Great White Shark or Man-eater (Carcharodnn rondeleti) 14. Basking Shark (Cetorhinus maximus) .... 15. Thresher or Fox Shark (A lopi as vulpes) 16. Common Nurse Shark or Gata (Ginglymostoma cirratxim) 17. Wobbegong or Carpet Shark (Orectolobus barbatus) 18. Zebra Shark {Stegostoma tigrinum) .... 19. Great Blue Shark (Carcharinus glaucus) 20. Tiger Shark (Galeocerdo arcticus) .... ji. Hammer-head Shark (Sphyrna zygcena) 22. Greenland or Sleeper Shark (Somniosus microcephalus) . 23. Bramble or Spinous Shark {Echinorhinus spirwsns) 24. Monk-fish or Angel-fish (Squalina squatina) . 25. Ulavi or Plough-headed Ray {Rhynchobatis djiddensis) . 26. Common Saw-fish (Pristis pectinatus) 27. Mediterranean Torpedo (Torpedo marmoratus) 28. Common Skate (Raja batis) 29a. Stingaree or Clam-cracker (Trygon centrums) 296. Common Eagle Ray (Myliobatis aquila) 30. Cow-nose Ray (Rhinoptera quadriloba) 31. Manta or Greater Devil-fish (Manta birostris) 32. Mobular (Mobula mobular) 33. Common Sturgeon (Acipenser sturio) 34. Tarpon (Megalops atlanticus) 35. Common Conger (Conger conger) 36. Common Gar-fish (Belone belone) GIANT FISHES, WHALES AND DOLPHINS Vll FIG. 37. How a Flying-fish flies ...... 38. Northern Deal-fish (Trachypterus arcticus) . 39. Common Stone Bass or Wreck-fish (Polyprion americanus) 40. California Jew-fish (Stereolepis gigas) .... 41. New Zealand Yellow-tail (Seriola grandis) . 42. Leer-fish (Lichia amid) ...... 43. Meagre or Kabeljau (Scicena holokpidota) . 44. Common Escolar or Oil-fish (Ruvettus pretiosus) . 45. Snoek (Thyrsites atun) ...... 46. Scabbard-fish (Lepidotus caudatus) .... 47. Black Scabbard-fish (Aphanopus carbo) 48. Common Tunny (Thunnus thynnus) .... 49. Atlantic Albacore (Germo alalunga) .... 50. Atlantic Yellow-finned Tuna (Neothynnus argentivitiatus) 51. Peto or Wahoo (A canthocybium solavdri) 52. Louvar (Luvarus imperialis) ..... 53. Black-finned Barracuda (Sphyrcena commersoni) . 54. Striped Marlin (Tetraplurus mitsukurii) 55. American Sail-fish (Istiophorus americanus) . 56. Sword-fish or Broadbill [Xiphias gladius) . 57. Shark-sucker (Echeneis naucrates) .... 58. Common Sun-fish (Mola mola) ..... 59. Teeth of Sharks and Rays ..... 60. Greenland Right Whale (Balcena mysticetus) 61. Black Right Whale (Balcena glacialis) 62. Skeleton of Pigmy Right Whale {Neobalana marginata) 63. Finner Whale or Common Rorqual (Balcenoptera physalus) 64. Sei Whale or Rudolphi's Rorqual (Balcenoptera borealis) (After Andrews) ....... C5. Piked Whale or Lesser Rorqual (BalcBnoptera acutorostrata) 66. Californian Grey Whale (Rhachianectes glaucus) 67. Sperm Whale (Physeter catodon) 68. Pigmv Sperm Whale (Kogia breviceps) 69. Bottle-nosed Whale (Hyperoodon rostratus) 70. Cuvier's Beaked Whale (Ziphius cavirostris) 71. Sowerby's Whale (Mesoplodon bidens) . 72. Lower jaw of Berardiiis .... 73. Skull and lower jaws of species of Mesoplodon 74. Killer Whale (Orcinus orca) 75. False Killer (Pseud orca crassidens) 76. Irawadi Dolphin (Orcella brevirostris) . 77. Pilot Whale (Globicephala melcena) 78. Burmeister's Porpoise (Phocczna spinipinnis) 79. True's Porpoise (Phoccznoides truei) 80. Spectacled Porpoise (Phoccsna dioptrica) 81. Finless Black Porpoise (Neomeris phoccenoides) .82. Right Whale Dolphin (Lissoaelphis peronii). (After Gray) Vlll LIST OF ILLUSTRATIONS FIG. 83. Heaviside's Dolphin {Cephalorhynchus heavisidei) 84. Hector's Dolphin (Cephalorhynchus hectori). (After Beneden) ....... 85. Commerson s Dolphin (Cephalorhynchus commersonii) 86. White-sided Dolphin (Lagenorhynchus acutus) 87. Lagenorhynchus cruciger ..... 88. Peale's Porpoise (Lagenorhynchus australis) 89. Dusky Dolphin (Lagenorhynchus obscurus). 90. Bottle-nosed Dolphin (Tursiops truncatus) . 91. Rough-toothed Dolphin (Steno rostratus) 92. Prodelphinus euphrosyne. (After Pucheran) 93. Gadamu (Solatia gadamu) .... 94. Skulls of Common Porpoise and Common Dolphin 95. Gangetic Dolphin (Platanista gangetica) 96. Amazonian Dolphin (Inia geoffrensis) 97. La Plata Dolphin (Pontoporia blainvillei) A Living Fossil (Latimeria chalumnae). (After Smith.) Van PAGE 317 317 317 323 323 323 325 325 325 335 335 335 340 340 340 XVf Century PREFACE The past ten or fifteen years have revealed a marked growth in the popular interest in the life of the sea, a growth which is perhaps associated with the ever-increasing popularity of the pleasure cruise. So numerous and varied are the inquiries received at the British Museum (Natural History) for facts concerning whales, dolphins, and the larger kinds of fishes, that the authors feel that little apology is needed for the publication of this book. Most of these inquiries come from travellers, seafaring men and sportsmen, and it is mainly for them that the book has been written. Arranged in convenient form for handy reference, the authors hope, nevertheless, that it will prove to be more than a mere reference work, and will provide general reading for anyone interested in the study of marine life. From the outset the question as to which animals should be included and which omitted provided a difficulty, but, as far as the whales and dolphins are concerned, it was decided to include all the better-known forms. In the case of the fishes, all those that ordinarily grow to a length of 6 feet or more find a place, as well as certain smaller forms, such as the flying-fishes, pilot-fishes, and remoras, which are so often observed during a sea voyage. The term " fishes " is, of course, used in a strictly scientific sense, and includes only those animals with a backbone (Vertebrates), adapted for a X GIANT FISHES, WHALES AND DOLPHINS purely aquatic life, that propel and balance themselves by means of fins, and obtain oxygen for breathing from the air dissolved in the water by means of gills. Thus, such creatures as sponges, jellynshes, crustaceans, shellfish, and even the gigantic squids of the ocean depths, often popularly referred to as " fishes ", are excluded, since they all lack a backbone. The main part of the book is divided into two sections, one devoted to whales and dolphins, the other to fishes, and the authors are each responsible for one of these sections. Only in the case of the introductory chapter has actual collaboration been attempted. At the same time, every effort has been made to ensure that the method of treatment of the various forms and the arrangement of the subject-matter is roughly the same throughout. Zoologically speaking, the two groups of aquatic animals dealt with in the separate sections of the book are vastly different in size and importance. In classifying the great group of Vertebrates, the zoologist divides this into a number of primary divisions or classes. These classes are : Lampreys and Hag-fishes, etc. (Marsipobranchii) ; Sharks, Rays and Chimaeras (Selachii) ; Bony Fishes (Pisces) ; Frogs, Toads, Newts, Salamanders, etc. (Batrachia) ; Reptiles (Reptilia) ; Birds (Aves) ; and Mammals (Mammalia). The Cetaceans (Whales, Dolphins, Porpoises, etc.) represent one of the Orders into which the class Mammalia is further subdivided, whereas the " fishes " include no less than three classes of Vertebrates. The aim of the book is twofold. In the first place, by the provision of simple keys, descriptions and accurate illustrations, it is hoped that the reader may be able to identify any of the whales, dolphins or large fishes that he may be in a position to examine. It is not claimed that these will enable a whale or fish to be recognized when swimming in the sea, although in many cases careful perusal of the descriptions and figures should render this possible. In the second place, the authors have tried tc provide a readable account of the appearance, size, habitat, mode of life, food, breeding habits, economic importance and so on of the various creatures that find a place in the book. They have not hesitated to draw upon the subject-matter of a large number of books and scientific papers not readily available to the general public. PREFACE xi The use of technicalities has been avoided as far as possible, and these are included only where, their omission would be at the expense of clarity. The introductory chapter has been designed to explain the meaning of the few scientific terms whose use has proved unavoidable, as well as to illustrate some of the more characteristic features of the Cetaceans and Fishes, so that the reader may have no difficulty in following the descriptions of the various forms given in later pages. A few words are necessary concerning the scientific names that have been used for the fishes. With the 6-foot rule as the standard for inclusion, it follows that we shall sometimes be dealing with a whole family of fishes, sometimes with the members of a single g^nus, and sometimes with one or more species selected from a genus. Immediately in front of each description is given the popular name or names of the fishes dealt with therein, and the scientific name of the family or genus (sometimes both) to which they belong. For convenience it has been considered preferable to retain in this book the larger and more conservative generic groupings favoured by the older naturalists, so that the generic names employed for certain forms may not correspond with those to be found in some modern works on fishes. Since modern authorities themselves are by no means in agreement as to the limits of fish genera, or as to the names by which they are to be called, the advantage of this plan appears clear. To take an example, in the case of the Blue Sharks or of the Whip-tailed Sting Rays, & number of species have here been grouped together under the generic names Carcharinus and Trygon respectively, but many modern authorities would subdivide each of these groups into several distinct genera. Finally, the authors wish to take this opportunity of thanking Lieut. -Col. W. P. C. Tenison, D.S.O., for his collaboration and for the care and skill that he has displayed in the preparation of the illustrations. All these have been drawn specially for this book, from specimens in the British Museum (Natural History), as far as these were available. J. R. N. London, 193;: F. C. F. INTRODUCTION. A glance at a typical Fish and a typical Cetacean (whale, dolphin or porpoise) reveals at once a general similarity in bodily form. This resemblance, however, as might be expected in two animals with such markedly divergent ancestral his- tories, is a purely superficial one, and a closer study of their anatomy reveals a number of important differences. The fish has always lived in the water, but the whale is a mammal that has exchanged a terrestial for an aquatic life, a change that has been accompanied by the assumption of a stream-lined and superficially fish-like form, designed to slip easily through the water. The whale has also undergone a number of other important modifications in connection with its adopted environment. For convenience, as well as for descriptive purposes, we may divide the body of a fish or cetacean into three regions : a head, a trunk and a tail (Figs, i, 2). As a general rule there is no trace of the neck so characteristic of most land Verte- brates, and the outline of the head passes into that of the trunk smoothly and without any sign of constriction. Similarly, the trunk itself merges imperceptibly into the tail, the line of division between the two regions being denoted by the vent. In fishes, the last of the external gill-clefts in the Selachians (sharks and rays), and the hinder edge of the bony gill-cover, INTRODUCTION xiii or, if this is absent, the gill-opening in the true or Bony Fishes, marks the boundary between the head and the trunk. In addition to the skin, most fishes are provided with another covering in the form of scales. In the Selachians these scales take the form of small, tooth-like bony structures known as dermal denticles (p. 2), but in the Bony Fishes the scales are usually thin, flexible bony plates, regularly arranged, and overlapping one another like the tiles on a roof. The skin of the whales has lost all trace of sebaceous and sweat-glands. Hair, so typical a feature of ordinary mammals, is reduced to a few scattered bristles on the surface of the head and snout, and is more frequently seen in young than in adult specimens. There are never any scales on the body, and the surface of the skin is exceedingly smooth, with a bright glossy sheen when fresh and dry. Immediately below the skin in a fish are the muscles, but in the cetacean there is a fibrous layer loaded with oil, known as blubber, in between. This acts mainly as an insulator, to prevent loss of heat, for it must be remembered that, unlike the generality of fishes, the whale is a warm-blooded animal and has to maintain a constant temperature within its body. The lateral line is a characteristic feature of most fishes, but nothing of this nature is found in any cetacean. This forms a kind of tunnel beneath the skin, which communicates at regular intervals with the surface by a series of small openings, which in scaly Bony Fishes are situated in a lengthwise row of special scales running along each side of the body. The lateral tunnels are continued on the head, where they form a branching system running in the bones of the skull. On the inner walls of the tunnels, which are filled with a jelly-like mucus, are special organs of sense, which alternate with the openings to the exterior. The function of the lateral line system is as yet imperfectly understood, but it is probably connected with the perception of movements in the water, perhaps enabling the fish to avoid obstacles, and providing it with a hint as to the presence of prey or natural enemies. It may be noted that the internal ear of a fish, which serves as an organ of balance as well as of hearing, is nothing more than a greatly enlarged and specially modified lateral line organ. The fins, which provide so characteristic a feature of any xiv GIANT FISHES, WHALES AND DOLPHINS fish, are supported by structures known as fin-rays, and are further strengthened at their bases by special parts of the internal skeleton. The fins are of two kinds : median or unpaired, and paired. The median fins consist of a dorsal in the middle line of the back, an anal on the middle line of the belly behind the vent, and a caudal or tail-fin at the hinder end of the fish. The fleshy part of the tail behind the dorsal and anal fins is known as the caudal peduncle. The paired fins are of two kinds only, the pectorals and pelvics, corresponding qperc*Ji ftamajidt C+mAJ Topography of a Fish. respectively to the fore- and hind-limbs of land Vertebrates. The pectorals are nearly always placed just behind the head, but the position of the pelvics varies in different fishes, some- times being well back on the belly, sometimes more or less below the pectorals, and sometimes in front of the pectorals. The form and position of the various fins present considerable diversity in the different groups of fishes, and are of some importance in classification (Fig. i). We have seen that the fins are supported by structures known as fin-rays, which are usually joined to one another by fine membrane. In the Selachians the rays are all covered over with a thick skin and are quite invisible. In many Bony Fishes all the fin-rays have the form of flexible jointed rods (soft-rays), which may be simple or branched and brush-like INTRODUCTION XV at their tips, but in many others the front rays of the dorsal and anal fins and the outer rays of the pectorals and pelvics are transformed into sharply pointed, stiff spines, sometimes with saw-like edges. Such spines provide useful offensive or defensive weapons. Dorset o, StccA /iJt- TYyyoej- -Topography of a Cetacean. Fig. 3. — Flipper of a Sperm Whale. In the cetaceans the hinder end of the body is flattened out into flukes (Fig. 2). These fleshy extensions are set in a horizontal plane, whereas the caudal fin of a fish is always set in a vertical plane ; this position of the tail provides a ready means of distinguishing any fish from any cetacean. On the middle of the back of cetaceans there is very frequently a fleshy eminence, the dorsal or back fin, which may be triangular xvi GIANT FISHES, WHALES AND DOLPHINS or sickle-shaped, but is never supported by any internal skeleton (Fig. 2). There is no structure corresponding to the anal fin of a fish. The fore-limbs of a cetacean are modified to form flippers, which are superficially like the pectoral fins of a fish, but within their solid flatness, instead of the irregularly arranged cartilages or bones of the pectoral fins, may be found the bones that constitute the limb skeleton of a typical land mammal ; upper arm, fore arm, wrist and finger bones are all present (Fig. 3). No external trace of hinder limbs remains, but within the body in the neighbourhood of the vent two small bones, entirely free from the backbone, represent the two halves of the pelvis, and, occasionally associated with them, are small nodules of bone — all that remains of the leg bones. In the vast majority of fishes the propulsion of the body is brought about mainly by means of lateral flexions of the muscular tail, aided by movements of the caudal fin. That is to say, the tail is lashed vigorously from side to side in order to drive the fish forward. The cetaceans swim in much the same way, but the movements of the tail are in a different plane. The horizontal position of the flukes is undoubtedly associated with the necessity for the whale to rise to the surface of the water periodically to renew the supplies of air to the lungs. The dorsal and anal fins of a fish, and probably also the back fin of the whale, normally serve as keels, and their purpose is to give stability to the body, but some fishes with fairly long and flexible fins make use of wave-like move- ments of these fins to propel the body at slow or moderate speed. The pelvic fins of a fish assist the dorsal and anal in keeping the body balanced, and appear to function after the manner of bilge keels. The pectoral fins, like the flippers of a cetacean, are probably used mainly for steering and balancing, but also act as brakes to check forward movement. The head of a fish or a cetacean, although presenting great diversity in size and appearance, possesses all the usual organs that might be expected in a Verbetrate animal — snout or muzzle, nostrils, eyes, mouth and so on. In a fish the nostrils are scarcely ever used for breathing purposes, and serve merely as organs of smell. In a cetacean the nostrils form a single or double opening called the blowhole, and are situated, almost INTRODUCTION xvii without exception, on the highest point of the head and usually at some distance from the tip of the snout (Fig. 2). The eye of a fish is built on the same general plan as that of other Vertebrates, but is somewhat modified for vision under water. Neither fishes nor cetaceans show any traces of external ears. In a fish there is no visible external aperture, and the internal organ associated with the sense of hearing is of comparatively simple design. In a cetacean the aperture is situated between eye and edge of flipper, and is so small and inconspicuous that even in a 100-foot monster its diameter is not greater than that of a lead pencil. The mouth, both in fishes and cetaceans, varies greatly, not only in size and shape, but also in position. In fishes the jaws are usually provided with teeth of one form or another. Among the cetaceans, teeth are present only in the members of the sub-order Odontoceti, the Toothed Whales (p. 256), and, although they are very variable in number and size, they do not show any differentiation into incisors, canines and molars in any living species. They are all uniform, usually conical in shape, and the range in number extends from 1 to more than 50 in a tooth row. Teeth may be present in both jaws, or they may be restricted to either the upper or the lower jaw. In certain forms such teeth as persist are concealed beneath the gums throughout life, so that the animals appear to be toothless. The members of the sub-order Mystacoceti, the Whalebone Whales, feed in quite a different manner, and instead of teeth, the characteristic whalebone or baleen is developed. This is horny in structure, and is suspended in two rows of flattened plates from the under surface of the rostrum (p. 203). The two skulls illustrated here (Figs. 4, 5) show the main differences between the mouths of the Whalebone and Toothed Whales. With the organs of respiration we encounter one of the most important differences between the fishes and cetaceans. The fish obtains the oxygen necessary for life from the air dissolved in the water by means of special organs known as gills. When a fish breathes, water is taken in through the mouth, and, after passing over the giil-plates or gill-filaments, is expelled through the external gill- openings in the sides of the " neck ". These plates are richly supplied with fine blood-vessels, in which the XV111 GIANT FISHES, WHALES AND DOLPHINS blood is separated from the surrounding water only by a delicate membrane. As the water bathes the plates, the blood absorbs the necessary oxygen, and at the same time liberates the waste products from the bodv in the form of carbon dioxide. Fig. 4. — Skull of a Whalebone Whale (Californian Grey Whale). Skull of a Toothed Whale (False Killer Whale). The principle of respiration is essentially the same in all fishes, but the form and arrangement of the gills is somewhat different in the Selachians and the Bony Fishes ; these differ- ences are illustrated in the accompanying diagrams (Fig. 6). Briefly, in Selachians, the walls of the gullet are perforated on each side by a row of from 5 to 7 narrow openings, the internal gill-clefts, each of which leads into a kind of flattened pouch, INTRODUCTION XIX which in turn communicates with the exterior by a compara- tively narrow cleft, the external gill-cleft or external gill- opening. There are, thus, from 5 to 7 external openings in the sides of the " neck " The iointed gristly structures ^Section tArou^A CD Fig. 6. — Respiratory organs in a Shark and a Bony Fish. known as the gill-arches lie between the gill-pouches, and encircle the walls of the gullet like hoops to provide supporting girders. The gill-plates are placed on the opposing walls of each of the gill-pouches. In the Bony Fishes there is the same series of internal openings in the walls of the gullet, but, instead of opening directly to the exterior by a similar number XX GIANT FISHES, WHALES AND DOLPHINS of external gill-clefts, they all open into a common branchial chamber on each side, with a single external gill-opening at the back of the head. The outer wall of this chamber is usually provided by a movable bony flap, the gill-cover or operculum, and, if this is lifted up, the delicate red gill-plates, attached in double rows to the outer edge of each of the hoop- like bony gill-arches, may be observed crowded together in the underlying cavity. In those fishes whose normal food consists of more or less minute creatures swimming in the water, there is clearly a danger of some of these escaping by way of the gill-clefts and perhaps clogging or injuring the delicate gill-plates. To lessen this danger special structures known as gill-rakers may be present, which function in exactly the same way as the baleen plates of the whalebone whales, and serve to strain the water, which is to pass over the gills, and to prevent any solid particles from passing with it. These gill-rakers take the form of a double row of more or less stiff appendages on the inner edge of each hoop-like gill-arch, which project across the inner openings in the walls of the gullet. In fishes that feed upon minute animals and plants the gill-rakers form long, slender bristles, and are very numerous and set close together; in those whose food consists mainly of other fishes the rakers are few in number, stouter, and set wider apart, or they may even be reduced to a few bony knobs. Mention may be made here of the organs known as spiracles, which are found in many of the Selachians, but in only one or two Bony Fishes. There is one spiracle on each side of the head, and this takes the form of a (usually) small opening situated close behind the eye. The spiracle actually represents the vestige of what was once another external gill-cleft. The cetacean obtains its supplies of oxygen from the atmo- spheric air by means of lungs like any other mammal, the air being taken in by way of the blowhole. The channel from nostrils to lungs is modified so that the windpipe extends to fit round the hinder end of the nasal Canal. In this way a continuous connection is made between blowhole and lungs, so that no water can get into the latter by way of the mouth! The blowhole is closed by an elaborate set of pocket valves when the animal is submerged. INTRODUCTION xxi The internal skeleton of a fish calls for little or no comment here, and for details of the various bones the reader is referred to a good text-book of zoology. In the cetaceans the bones are spongy in texture and in form rather simplified, so that, in the backbone, for instance, the elaborate articulation between one bone and the next, common in ordinary land mammals, tends to be lost. The skull is very specialized, as may be seen in the accompanying figures (Figs. 4, 5), and the articu- lation of the lower jaw with the skull is much less complicated than in most land mammals. The 7 vertebrae of the neck are very much compressed. They remain distinct in the more primitive members of the group, but in the rest the first 2 or 3 may be fused, or all 7 merged into one bony unit. The sacrum of land mammals, formed by the fusion of vertebrae between the trunk and tail elements of the backbone, is completely wanting in cetaceans ; all the vertebrae in this region are separate, changing gradually in form from trunk to tail. Of the internal organs it will be necessary to mention only the air-bladder, an organ peculiar to Bony Fishes, and of considerable importance in classification. When present, this has the form of a long, cylindrical bag, with glistening silvery walls, situated within the body-cavity and just below the backbone. This bladder is filled with a mixture of gases, and in the majority of fishes serves as a hydrostatic organ or float, enabling its possessor to accommodate itself to the varying pressure encountered at different depths. In a few forms, however, it serves as an accessory breathing organ, functioning exactly like a true lung. The air-bladder may be connected with the gullet by a narrow pipe, or it may be entirely enclosed. Finally, in the possession of mammary glands and teats, by means of which they can suckle their young after birth, the cetaceans differ from all the fishes, in which no such organs are developed. Even if the young of fishes are brought forth alive, they are never suckled by the mother. The paired mammary slits of the cetacean lie on either side of the genital opening, and give access to little cavities in which lie the retracted teats. There are two apertures on the under surface of a whale, situated about two-thirds to three-quarters of the body length from the snout ; the one nearer the head is the XX11 GIANT FISHES, WHALES AND DOLPHINS genital aperture, the other the vent or anus. It is possible to distinguish the sex by the distance between the two aper- tures, these being closely approximated in the female and farther apart in the male. There is a modification in these aquatic mammals of the normal manner of suckling the young, necessitated by the environment in which they live. The mammary glands have large sinuses or reservoirs, in which the milk collects, and which, by the contraction of certain body muscles, are forcibly emptied by way of the teat into the mouth of the young, so that the whole process of feeding is greatly accelerated. Part I GIANT FISHES BY The Late J. R. Norman, F.L.S. CHAPTER I: SHARKS. Characters of Selachians. General features of the Sharks. Comb-toothed or Cow Sharks. Six-gilled Shark or Griset. Seven-gilled Shark or Perlon. Sand Sharks and Elfin Sharks. Sand Sharks or Slender-toothed Sharks. Elfin or Goblin Shark. Mackerel Sharks. Porbeagles and Mako Sharks. Great White Shark or Man-eater. Basking Shark. Thresher or Fox Shark. We have already seen that the Sharks, together with their relatives the Rays and the small and little-known fishes called Chimaeras, constitute a distinct class, Selachii, and may be collectively described as Selachians, a name derived from the Greek word meaning a shark. The other two classes covered by the popular term " fishes " are the Marsipobranchii (Lampreys and Hag-fishes) and the Pisces (Bony Fishes). The Marsipobranchii will not concern us here, as the members of this group are all of small or moderate size, but we may briefly indicate the principal differences between a Selachian and a Bony Fish — between, say, a Shark and a Tarpon. The skeleton of a Shark is entirely cartilaginous or gristly, and, although it is sometimes strengthened by the addition of limy matter, there are never any true bones. The slits in the walls of the gullet in the Shark open directly to the exterior by a coi responding series of external gill-openings, 5 to 7 in 2 GIANT FISHES number, situated on each side oi the hinder part of the head ; whereas, in the Tarpon these open into a common branchial chamber on each side, protected on the outside by a bony gill-cover or operculum, and with a single opening to the exterior at the back of the head. The Shark has a single nostril on each side of its snout ; the Tarpon (but not quite all Bony Fishes) has two. There is no air-bladder in the Shark, but this organ is developed in the majority of Bony Fishes. The male Shark is provided with curious organs called " claspers ", organs which are unknown in Bony Fishes. Finally, instead of being covered with overlapping scales as in the Tarpon, the body of a Shark is armed with numerous closely-set bony nodules, known as dermal denticles. The claspers, dermal denticles, and the teeth of Selachians are worthy of further consideration. Unlike the generality of Bony Fishes, the eggs of a Shark or Ray are fertilized within the body of the female as in most higher animals, and there is consequently a definite union of the sexes. The claspers of the male, which are actually modified portions of the pelvic fins and have a highly compli- cated internal structure, are used for the purpose of introducing the seminal fluid into the body of the female. The surface of a Shark or Ray is nearly always rough or prickly to the touch, and this is due to the presence of the innumerable tiny denticles embedded in the skin and covering the whole of the head, body and parts of the fins. These denticles are usually arranged in regular oblique rows, and, examined with a hand lens or under the microscope, each may be seen to consist of a bone-like base, which is embedded under the skin, and therefore invisible during life, and a superficial enamel-covered spine, which projects freely outwards and backwards. An even more intimate examination of one of the denticles reveals that in its structure it is essentially similar to one of the teeth in the jaws, being made up mainly of a substance known as dentine, with an internal pulp cavity and an outer coating of enamel. Thus, the very interesting fact emerges that the teeth of Selachians and Bony Fishes, indeed of all higher animals, including ourselves, must have arisen in the first place from the dermal denticles of the Shark's skin, the denticles in the region of the jaws having SHARKS 3 become enlarged or joined up with their neighbours to form the teeth. Another feature of interest concerning the teeth ol Selachians is the fact that instead of being more or less firmly attached to the jaws they are simply embedded in the gums. Further, a Shark does not retain the same set of teeth throughout the greater part of its life, nor is it content with two sets like ourselves, but provision is made for a constant supply of new teeth to replace those in use — a most enviable arrangement ! If the jaws of a large Shark be examined, the young teeth can be seen lying in a shallow cavity on the inner surface of the jaw closed by membrane (Fig. 59). They lie closely packed, one on top of another, with their points directed downwards in the lower jaw, upwards in the upper jaw. Those near the edges of the jaws can be seen to be in a more advanced stage of development and in a more erect position than those further back, and are, in fact, all ready to take the place of the row at present in use as soon as these shall be worn out and cast off. The forward movement of the whole phalanx of teeth goes on throughout life, a row or two doing duty for a time, only to be replaced by their successors, standing by, as it were, in the rear ! The number of different kinds of Selachians living to-day is far less than that of the Bony Fishes, but the class includes, nevertheless, a large and diverse assortment of types. The origin of the class may well be said to be wrapped in the mists of antiquity, for our knowledge of the earliest Sharks is based upon the discovery of isolated denticles, teeth, fin-spines and so on, buried as fossils in the rocks of the Silurian and Devonian periods of the earth's history. Since there is reason to believe that these rocks were laid down at least 200,000,000 years ago, the class is a very ancient one, and the very diversity of the fossils suggest that even at this remote age there already existed a wealth of different kinds of Sharks. Unlike the Bony Fishes, comparatively few Selachians can be described as of very great value to mankind. Some of the smaller Sharks and Rays, it is true, provide wholesome and nutritious food, and in parts of the Orient there is quite a respectable trade in shark-fins for use in making soup The crude skins of certain Sharks and Rays, with the dermal 4 GIANT FISHES denticles in situ, are used by carpenters and cabinet-makers, as well as by metal-workers and others, while the dyed skins, suitably prepared, provide a handsome shagreen for ornamental purposes. With the denticles removed, and after undergoing a special tanning process, the skins of certain Sharks and Rays provide a strong and durable leather, and there is nowadays a brisk demand for shoes, bags and other articles made from this commodity. All the existing Sharks are grouped into a single order, the Pleurotremata (literally " side openings "), and may be readily distinguished from the Rays, which form the second order of existing Selachians, the Hypotremata (literally " under openings "), by the position of the external gill-clefts, which are placed on the sides of the head ; by the free front edges of the pectoral fins, which are never joined to the sides of the body or head ; and by the distinct margins of the eyes. The order Pleurotremata includes a number oi genera and species, ranging from veritable monsters 50 feet or more in length to comparative dwarfs scarcely more than 2 feet long. Sharks are to be found in nearly all the seas of the world, and at most depths ; a few even ascend rivers beyond the influence of the tides, and at least one lives permanently in fresh water. The great majority are active animals, chasing and hunting down their prey, aided by a very well-developed sense of smell. All have a carnivorous diet, but the food taken varies from shellfish and tiny shrimp-like creatures to fishes, marine mammals and even man himself, and includes also a good deal of carrion and garbage. Most of the larger Sharks are viviparous, that is to say the eggs hatch within the body of the mother and the young are brought forth alive, but many of the smaller kinds produce large yolky eggs, which are deposited in horny protective cases. COMB-TOOTHED OR COW-SHARKS. (Family Hexanchid^e.) Sharks with a comparatively long body and a long unequally lobed tail. The snout is pointed and overhangs the mouth, which is large and not connected by grooves with the nostrils. SHARKS 5 The teeth are different in the two jaws, but are mostly flattened and more or less comb-like in character (Fig. 59) . The spiracles are small, and the external gill-clefts, 6 or 7 in number on each side, are all placed in front of the pectoral fins. There is only 1 dorsal and 1 anal fin, and both are without spines. There is no pit at the root of the caudal fin. The Comb-toothed Sharks are found in all warm seas, but as a rule are not numerous. All are viviparous. Fossil remains, mostly teeth, date back to the Cretaceous period. SIX-GILLED SHARK OR GRISET. (Genus Hexanchus.) Fig. 7. There are 6 external gill-clefts on each side. The coloration is uniformly dark brownish-grey or black above, shading to paler below ; there is usually a pale streak along the middle of each side. Young individuals are brown. Grows to a length of 26 feet or more. The single known species (H. griseus) is found in the Mediter- ranean, Atlantic and Pacific. The so-called Shovel-nosed Shark (H. corinus) from the coast of California is probably only a variety. Little is known of the habits of this shark, but it is believed to be fierce and voracious, and to feed almost entirely upon fishes. It occasionally strays close to the British coasts, especially in the summer months, and there is a record of one, 26 feet 5 inches long, caught at Polperro, Cornwall, in February, 1846. It is of no use as food, and those who have sampled the flesh report a strong purgative effect. SEVEN-GILLED SHARK OR PERLON. (Genus Heptranchias.) Fig. 8. There are 7 external gill-clefts on each side. The coloration is brown or grey above, shading to paler below ; the back, especially in the young, is sometimes provided with small, scattered, dark spots. Grows to a length of more than 10 feet. The Perlon {H. perlo) is found in the Mediterranean, in the GIANT FISHES Fig. 7. — Six-gilled Shark or Griset (Hexanchus griseus). Fig. 8. — Seven-gilled Shark or Ferlon (H eptranchias perlo). Fig. 9. — Sand Shark or Slender-toothed Shark (Odontaspis laurus) SHARKS 7 Atlantic, and in the neighbourhood of Japan. Other species of Seven-gilled Sharks (H . platycephalus , H. pectorosus) occur in the Mediterranean, Indian Ocean, Eastern North Pacific, Patagonia, Australia and New Zealand. Like the Griset, this shark is a fish-feeder. One species is not uncommon round the North Island of New Zealand, where the Maoris called it Tuatini, and are reported to have used its teeth to make a saw-like instrument (Ripi or Mira tuatina) for cutting human flesh. It is of some interest to note that, whereas in South Australia this shark is regarded as dangerous to man, in New Zealand the same species is recorded as harm- less. In Japan the Perlon is known as the " Aburazame " or Oil Shark, on account of the oil yielded by its liver. SAND SHARKS AND ELFIN SHARKS. (Family Odontaspid^;.) Sharks with a long body, flattened head, and sharp snout. There is no third eyelid, and no grooves connecting the mouth with the nostrils. The mouth is large and crescent-shaped, and lies below the snout. The teeth are large, long, slender, and roughly awl-shaped, with smooth edges ; most teeth have i or 2 small points at the base on either side of the main cusp (Fig. 59). The spiracles are small. The external gill-clefts are 5 in number on each side, and are all placed in front of the pectoral fins. There are 2 dorsal fins, which are nearly equal in size and without spines, and 1 anal fin. The tail is not provided with a keel, is long and flattened, and is asymmetrical in shape. These sharks are found in nearly all warm seas, and are believed to be viviparous. Fossil remains date back to the Cretaceous period. SAND SHARKS OR SLENDER-TOOTHED SHARKS. (Genus Odontaspis.) Fig. 9. The snout is short, and the mouth is capable of being protruded only to a moderate extent. The dorsal, anal and pelvic fins are all nearly equal in size. There is a pit at the 8 GIANT FISHES root of the caudal fin, and the lower lobe of the fin itself is distinct. The coloration is grey above, becoming paler beneath. The young are spotted and blotched with brown or black. Grows to a length of 10 to 12 feet. The Common Sand Shark (0. taurus) is found in the Mediter- ranean, in the Atlantic and in South African seas. Other species (0. ferox, 0. cucpidatus, 0. owstoni, 0. platensis) are found in the Mediterranean, Indian Ocean, Japan, South America, and in Australian and New Zealand seas. Some of these other species appear to grow to a somewhat larger size. The Sand Sharks are mostly of small or moderate size, but are of voracious habit, and subsist mainly upon a fish diet, although lobsters, crabs and squids are also eaten. While the vast majority of sharks appear to chase and seize their prey in a more or less haphazard manner, the Sand Shark may be said to be at times distinctly methodical in its manner of feeding. Mr. Coles describes how he saw a school of a hundred or more at Cape Lookout on the coast of New Jersey which surrounded a shoal of bluefishes, and forced them into a solid mass in shallow water, and then the entire school dashed in and attacked the prey. In Australian waters the sharks are said to attacK schools ot the fishes known locally as " Sea Salmon " or " Kahawai " as they migrate northwards in the summer-time near the beaches, causing great havoc among the fish. In this part of the world the two species of Sand Sharks are known respectively as " Grey Nurse " and " Blue Nurse ", and both have the reputation of being dangerous to bathers. The word " nurse ", sometimes written as " nusse ", is simply an ancient term for any large fish, and does not imply that the shark would be reliable with children ! Mr. Stead writes of the Grey Nurse that " these ' wolves of the sea ' rove along the eastern shores of Australia at least in thousands, freely entering harbours ". They are at times a great nuisance to fishermen, especially along the Atlantic coast of the United States, as they bite readily at a hook and are very destructive to nets. They are of little value to man, although the skin makes a good leather. SHARKS ELFIN OR GOBLIN SHARK. (Genus Scapanorhynchus.) Fig. 10. The snout is long and the mouth is capable of being greatly protruded. The dorsal fins are smaller than the pelvics or the anal. The pit at the root of the caudal fin is indistinct and the lower lobe of the fin itself is not very prominent. The coloration is generally greyish-brown, with the lower parts somewhat paler. The fins are all darker tov/ards their edges. Grows to a length of about 14 feet. The single known species (S. owstoni) is well known in Japan, and has also been recorded from the Indian Ocean. It probably has a much wider distribution in warm seas, for a second species which has been described from deep water off the coast of Portugal is probably identical. Originally discovered in 1898, this curious shark, locally known as " Tenguzame ", is taken from time to time in the warm Black Current or gulf stream of Japan. Its occurrence in the Indian Ocean was recorded in an unusual way. A , break " occurred in one of the submarine telegraph cables lying at a depth of about 750 fathoms on the ocean floor, and when the cable was brought to the surface for examination the damage was found to have been caused by a shark, one of whose broken teeth was lodged between the coils of wire protecting the cable. Closer examination of this tooth revealed its owner to have been an Elfin Shark. Little is known of the feeding habits of this creature, but, judging by the form of its curiously protrusible jaws, and the flat blade-like snout, it seems likely that it is mainly a ground feeder, and the supposition is that in the case quoted above the shark pierced the cable when feeding on barnacles or other succulent forms of animal life growing on its outer cover. It is of interest to note that the Elfin Shark is a survivor of a very ancient type, for fossil sharks have been found in Cretaceous rocks which are essentially similar to the form existing to-day. 10 GIANT FISHES MACKEREL SHARKS. (Family Lamnid/E.) Very similar to the Sand Sharks, but with a stout, torpedo- shaped body, and usually with a strong keel on each side of the tail. The spiracles are minute or absent altogether. Where the external gill-clefts are small, the fifth or last is placed just above the root of the pectoral fin ; where they are large, the last extends downwards just in front of the base of the fin. The second dorsal fin is much smaller than the first, and is placed nearly opposite to the anal. The caudal fin is roughly moon-shaped, with the lower lobe but little shorter than the upper, or the upper lobe is very long and the lower quite short. The pectoral fins are sickle-shaped. These are large surface-swimming sharks, found in most of the seas of the world. All are believed to be viviparous. Most of the genera appear to date back to the Cretaceous period. The general shape of these sharks, with their powerful tails, suggests active, predaceous creatures, capable of producing a high rate of swimming when required. The torpedo-like, streamlined body is eminently suited for rapid progression in a comparatively dense medium such as water, and the pointed snout overhanging the mouth provides an efficient cutwater which greatly facilitates progress. The coloration is practically the same in all the members of the family, being a dark bluish- grey on the back, shading away gradually to white on the lower parts. This is the typical coloration of most pelagic fishes, that is to say of fishes that habitually live at or near the surface of the sea, and illustrates the principle of what is known as obliterative shading. The shading is exactly the reverse of that which is produced by light thrown upon the fish from above, and its general effect is to destroy the appearance of thickness and to 'make the creature appear as a flat object. This type of coloration also tends to conceal the fish in its natural surroundings, for, seen against a background of dark water coloured very much like its own back, it is almost indistinguishable. SHARKS Fig. io. — Elfin or Goblin Shark (Scapanorhynchus owstoni). -it Fig. ii. — Common Porbeagle (Lamna comubica). Fig. 12. — Mediterranean Mackerel Shark (Lamna oxyrhynchus). 12 GIANT FISHES PORBEAGLES AND MAKO SHARKS. (Genus Lamna.) Figs. II, 12. The snout is pointed and overhangs the large, crescentic mouth, which is armed with large, slender, awl-shaped teeth, with smooth edges (Fig. 59) ; sometimes the teeth have a pair of small points at the base. There are 3 or 4 rows of teeth in use at a time, and these point either directly down the throat or towards the roof of the mouth. The external gill-clefts are wide. The coloration is dark bluish-grey above, shading to white beneath. Grow to a length of 12 feet or more. The Common Porbeagle (L. cornubica) is found in the Mediterranean, North Atlantic and North Pacific ; the American Porbeagle (L punctata), sometimes referred to locally as " Blue Shark ", is found on the eastern coasts of the United States ; the Sharp-nosed Mackerel Shark (L. tigris) ranges from Cape Cod to the West Indies ; the Blue Pointer or Mako Shark (L. glauca) inhabits the seas of Australia and New Zealand ; and the Mediterranean Mackerel Shark (L. oxy- rhynchus) is found in the Mediterranean and the adjacent parts of the Atlantic. The Common Porbeagle is not uncommon round the coasts of the British Isles. It is also known as the Beaumaris Shirk, as Pennant, in his ' British Zoology ', published in 1776, described a specimen from that district of North Wales. The fishermen sometimes refer to it as the " Bottle-nosed Shark ". All the Porbeagles and their allies are fierce, voracious sharks, and feed mainly upon fishes; herring, cod, whiting, hake, mackerel and dogfish being the favourite food ; squids and cuttlefishes are also included in the diet of some species. On the British coasts the Porbeagle is frequently captured In mackerel and salmon nets, or on lines that have been laid to catch bottom-living food-fishes, and when they entangle themselves in drift or gill-nets, and roll themselves up into an inextricable mass of twine, they can be a perfect nuisance to the fisherman. It is recorded that a shark taken in the cod gill-nets in the Firth of Forth at the beginning of the present century had in its stomach no less than eleven hooks with SHARKS 13 their attached hair " snoods ", the fish having passed along the fisherman's line and removed the catch by biting through the snoods. In Alaska its ravages among the salmon have earned for it the name of " Salmon Shark " Porbeagles and Makos are usually observed in small companies, although they can scarcely be called gregarious , sometimes a single shark will pursue its prey alone. The teeth are not adapted so much for cutting as for seizing the prey, which seems to be swallowed whole — a tribute to the digestive powers of this shark ! The Mako is said to be a lover of the open sea, where it dashes madly after its foou, and does not hesitate to attack boats, in the woodwork of which it not infrequently leaves some of its teeth. Most of the species are savage and dangerous to man, although the Porbeagles found close inshore in our own seas are mostly too small to cause much damage. Mr. Couch once wrote : " I have been informed of an instance, where in the prospect of being taken, it sprang at a fisherman and tore a piece out of his clothing." Little is known as to the exact breeding season of these sharks, but it has been ascertained that from 2 to 5 young are produced at a single birth. The Porbeagles are of no great economic importance. They are not normally used for food, although the flesh was at one time esteemed in some parts of France. One observer even describes the Common Porbeagle as emitting " an extremely disagreeable fetid smell ", and the ultimate fate of individuals captured by fishermen, if they are not killed and thrown back into the sea, is to be used as manure. In some parts of the world the oil from the liver used to be prized by curriers, but this minor industry has long since died out. It is of interest to note, however, that the liver of a 9-foot shark yielded as much as 11 gallons of oil. The Maoris of New Zealand use the teeth of the Mako Shark as articles of adornment. At least two members of this genus provide good sport for the sea angler. The Common Porbeagle is taken on rod and line on the west coast of Ireland, and to play a large shark from a small boat is no mean test of the angler's strength and skill. In the fish gallery at the British Museum there is a plaster cast of a fine specimen of 210 lb., which was taken in this manner by the Marquis of Sligo in 1932 off Achill Island. 14 GIANT FISHES co. Mayo. The Mako is still more famous as a game-fish, and in New Zealand waters provides strenuous and exciting sport. The world's record Mako Shark captured by fair angling stands to the credit of Mr. White-Wickham. It was taken in the Bay of Islands in January, 1931, was 11 feet 6 inches in length, and weighed 798 lb. The scientific name Lamna is derived from a Greek word for a horrible monster of man-eating tendencies, a creature used by the ancient Greeks to terrify naughty children. The term " Porbeagle " is simply a combination of porpoise and beagle, and refers to the porpoise-like appearance and active, predaceous habits. GREAT WHITE SHARK OR MAN-EATER. (Genus Carcharodon.) Fig. 13. Similar in appearance to the Porbeagles and Mako Sharks, but may be readily distinguished by the large, flat, triangular teeth, with fine, saw-like edges (Fig. 59). The coloration is bluish-grey or slaty grey above, shading to white beneath ; the fins are nearly all darker towards their edges. Grows to a length of 40 feet or more. The single living species (C. rondeleti) is found in all the warm seas of the world, ' and occasionally strays into more temperate waters. The Great White Shark, sometimes called the White Pointer, is just as swift and fierce as the Porbeagles, but is very much larger and more powerful. The huge, strong jaws, with their jagged knife-like teeth, are truly formidable weapons. There is a pair of jaws in the British Museum collection which belonged to a shark 36 feet in length, and the largest single tooth in either jaw is nearly 3 inches long. The " Challenger " Expedi- tion dredged some teeth from the floor of the Pacific Ocean which measured no less than 5 inches in length, and these must have belonged to a shark nearly 100 feet long. Fossil teeth from the rocks of the Eocene period and later are even larger, and indicate that veritable monsters must have roamed the seas in these times. The food of the Great White Shark consists mainly of fishes of SHARKS 15 all kinds, but the late Professor Jordan has recorded a specimen taken near Soquel, California, in 1880, which had a young sea lion in its stomach. Mr. Coles mentions a large shark more than 20 feet in length seen by him near Cape Lookout, North Carolina, in 1905, which he believed to be a Man-eater. " It apparently had no fear of us." he writes, " as it struck the side of the skiff with some force. It then swam away for a distance of several hundred yards, then turned and swam rapidly towards us. I was about to fire into it as a large loggerhead turtle arose to the surface and was attacked by the shark. The shark seized the turtle in its jaws and both disappeared beneath the surface. The next day I harpooned this turtle and found the upper shell for a width of nearly 30 inches showing the marks of the shark's teeth. The edge of the shell and the right hind flipper had been torn away." Further testimony as to the voracious habits and catholic diet of this shark is provided by the late Sir Frederick McCoy, who wrote as follows concerning a specimen from Port Phillip, Australia : "A specimen between 15 or 16 feet long had been observed for several days swimming around the ladies' baths, looking through the picket fence in such a disagreeable manner that the stationmaster had a strong hook and iron chain made so as to keep the rope out of reach of his teeth, and this, being baited with a large piece of pork made to look as much like a piece of lady as possible, was swallowed greedily, and then, with the aid of a crowd of helpers, the monster was got on shore. On opening the stomach, amongst a load of partially digested objects, a large Newfoundland dog was found, with his collar on, identifying him as one lost the day before, no doubt swallowed while enjoying a swim in the comparatively shallow water." Perhaps the queerest meal of all is one mentioned in what must rank as one of the most remarkable of all shark stories. This is vouched for by Mr. Frank Cundall, Secretary of the Institute of Jamaica, and though the shark was never identified it may well have been a Man-eater : " In the eighteenth century an American privateer was chased by a British man-of-war in the Caribbean Sea, and, finding escape impossible, the Yankee skipper threw his ship's papers overboard. The privateer was captured and taken into Port Royal. Jamaica, and the 16 GIANT FISHES Captain was there placed on trial for his life " — (Mr. Cundell says "for violation of the Navigation Laws"). "As there was no documentary evidence against him he was about to be discharged when another British vessel arrived in port. The Captain of this cruiser reported that when off the coast of Haiti a shark had been captured, and when opened the privateer's papers had been found in the stomach. The papers thus marvellously recovered were taken into court, and solely on the evidence which they afforded the Captain and crew of the privateer were condemned. The original papers were preserved and placed on exhibition in the Institute of Jamaica in Kingston, where the ' shark's papers ', as they were called, have always been an object of great interest. (Signed) A. Hyatt Verrill, New York, Nov. 20, 1915." According to the great Swedish naturalist, Linnaeus, it was the Man-eater Shark that swallowed the prophet Jonah, but this is only one of several claimants to credit for this feat. " Jonam Prophetum," he writes, " ut veteris Herculem trinoctem, in hujus ventriculo tridui spateo baeisse, verosimile est." The question as to whether or no a shark will attack and devour a man is one which has always been hotly debated, and which still remains a matter of considerable controversy. The normal diet of nearly all sharks consists of living animals, but not a few will turn scavenger when occasion offers, and will follow ships for days at a time in the hope of securing food thrown overboard The presence of unusual numbers of dangerous sharks in Sydney Hr^bour at one time was believed to be due to the discharge of blood and offal from the local abattoirs into the harbour waters, and there can be little doubt that sharks with their keen sense of smell may be attracted by the scent of blood. The stomach of one Great White Shark was found to contain "a tin can, a number of mutton bones, the hind quarters of a pig, the head and fore- quarters of a bull-dog, a quantity of horseflesh, and other and smaller things — as the auction bill says — too numerous to mention" — eloquent testimony to this shark's powers as a scavenger. It must be admitted that the bodies of drowned men and women would not come amiss to a hungry shark, and human corpses partially eaten after death are perhaps SHARKS 17 responsible for some of the stories of men killer1 and eaten by " man-eaters " ! Nevertheless, there are a number of well- authenticated cases of attacks on human beings, frequently resulting in the death of the victim, but it seems likely that the man happened to be particularly handy, as it were, and the shark more than usually hungry. Mr. Gilbert Whitley, of the Australian Museum, has compiled an interesting list of attacks in Australian waters. " 1920, March 8 . . . Young man. Cleveland Bay . . ." ; " 1920 (or earlier) . Head of native in shark's mouth. Thursday Island . . ." ; " 1924, Feb. 13 . . . Woman. Bronte, N.S.W. . . ." ; " 1925, June. Human arm found in shark. Princes Royal Harbour, W.A. . . ." ; " 1930, Dec. Female lunatic's body found bitten after death. Parramatta River, N.S.W." ; these are a few extracts taken at random from his grim list of some 80 cases. Of more than 40 records from New South Wales alone, about one-half of the attacks seem to have been fatal. Mr. Whitley classifies the modes of attack into five categories : (1) taking of surfers on ocean beaches ; (2) taking of bathers in harbours or well up rivers ; (3) bumping of boats, often viciously attacked ; (4) biting of hands, legs, or bodies of bathers ; and (5) net fishermen bitten when hauling in their catch. He further notes that the worst months for attacks are from October to April — the most popular bathing months in that part of the world ! Dr. F. A. Lucas, of the American Museum of Natural History, who has made a long and critical study of " shark stories ", is decidedly more comforting. He admits the existence of a number of well-authenticated records of fatal attacks in tropical seas, but states most implicitly that the danger of being seriously molested in temperate waters is very small indeed. It is noteworthy that at the end of the last century an American, Mr. Herman Oelrichs, offered the sum of $500 " for an authenticated case of a man having been attacked by a shark in temperate waters ", but the reward was never claimed ! Mr Lucas also disposes of one or two popular fallacies concerning shark attacks. " One of the commonest statements," he writes, " is that ' the shark bit off the man's leg as if it were a carrot ', an assertion that shows that the maker or writer of it had little idea of the strength of the l8 GIANT FISHES apparatus needed to perform such an amputation. Certainly no shark recorded as having been taken in these waters could possibly perform such an act, though this might occur if a shark thirty feet or more in length happened to catch a man fairly on the knee-joint where no severing of the bone was necessary. The next time the reader carves a leg of lamb, let him speculate on the power required to sever this at one stroke — and the bones of a sheep are much lighter than those of a man." Mr. Lucas goes on to record his disappointment at witnessing the efforts of a 12-foot shark to cut a chunk out of a sea lion. " The sea lion had been dead a week and was supposedly tender, but the shark tugged and thrashed and made a great to-do over each mouthful." His final advice is pertinent : " It is the part of wisdom to keep away from both ends of a captured shark, for a blow of the tail is almost as bad as a bite ". Although it had been assumed that, like its relatives the Makos and Porbeagles, the Great White Shark was viviparous, it was not until quite recently that the young were observed. In the summer of 1934 a shark was caught at Agamy, near Alexandria, in the Mediterranean, weighing 2\ tons, and of a length of 14 feet. It was only after a struggle lasting several hours that it could be landed by three boatloads of Egyptian fishermen. When it was cut open, 9 young were discovered inside, each 2 feet long and weighing 108 lb. Judging from the published photographs of the mother, and from the size of her babies, there can be little doubt that this was a Great White Shark, which is well known in these waters, and this must be very nearly the first time that the young have been observed. The Great White Shark is of practically no economic impor- tance. It has been taken on occasions by sea anglers, and the largest specimen taken on rod and line was captured at Bridle, New Jersey, in June, 1935 ; this weighed 998 lb., and was 12 feet long. The names Great White Shark and White Pointer refer to the pure white colour of its belly- The scientific name, Carcharodon, is derived from two Greek words meaning " rough " and " tooth ". SHARKS 19 Fig. 13. — Great White Shark or Man-eater (Carcharodon romlcleti). Fig. 14. — Basking Shark (Cctorhinus maximus). To 40 feet. FlG. 15. — Thresher or Fox Shark (Alopias vulpes) 20 GIANT FISHES BASKING SHARK. (Genus Cetorhinus.) Fig. 14. The snout is bluntly pointed and overhangs the mouth ; it is especially prolonged in young individuals. The mouth is large, with numerous, very small, conical teeth, set in several rows in both jaws. The spiracles are small and situated behind the eyes. The external gill-clefts are very large, extending nearly right round the neck, and the gill-arches in the walls of the gullet are provided with long, slender, comb-like rakers. The colour is bluish-grey, greyish-brown, or sometimes nearly black on the back, generally becoming paler on the lower parts. Grows to a length of 40 feet or more. The single species (C. maximus) is found in the temperate seas of both hemispheres, and is especially common in the North Atlantic. This relatively enormous shark is easily the largest to be found in temperate waters, and is exceeded in size only by the Whale Shark of tropical seas. It is a sluggish and quite inoffensive creature, which derives its name from the habit of lying motionless at the surface of the sea, as if basking in the sun. The inhabitants of Wales and the west coast of Ireland know it as the " Sun-fish " for the same reason, but this name is more properly used for a totally different fish (Mold) with similar habits (see p. 183). When " basking " it is generally to be seen with the dorsal fin and sometimes part of the back above the surface, but at times it will lie on its side or even belly uppermost. Sometimes solitary in its habits, sometimes swimming about in twos or threes, at certain times, probably during the breeding season, the Basking Shark may be observed in shoals of 60 to 100 individuals. Its seasonal movements are as yet imperfectly understood, but there appears to be a regular annual migration along the west coast of Ireland to the western isles of Scotland, and thence north- wards, the sharks approaching Ireland during the spring and reaching Norway during August. SHARKS 21 It is a by no means uncommon spectacle to see two large Basking Sharks swimming one behind the other in tandem fashion, and it is likely that the sight of two large dorsal fins showing above the water about 40 or 50 feet apart has sometimes provided the basis of one more story of the great " sea serpent ", especially if the foremost shark is swimming with his mouth open and his snout projecting above the surface. At the British Museum accounts are received from time to time of gigantic " sea serpents " left stranded by the tide,' generally on some remote and inaccessible shore, and these monsters are nearly always described as possessing a long and eel-like body Some of the descriptions are further elaborated by accounts of a " head just like a camel with an upturned nose ", and a " body covered all over with coarse white hair ". On closer investigation these monsters generally prove to be stranded whales or Basking Sharks in an advanced stage of decompo- sition, and the covering of hair is seen to be the frayed muscle- fibres produced by the disintegration of the flesh under the action of the waves. As the carcase of the shark rots on the shore, or is buffeted against the rocks, the whole of the gristly skeleton of the jaws and gill-arches, by far the bulkiest part of the head skeleton, as well as that of the pectoral and pelvic fins, is soon washed away, leaving only the backbone and the somewhat curiously shaped box-like cranium to represent the eel-like body and camel-like head respectively. In one or two cases of recorded " serpents " the shark in question was a male, and the remnants of the pectoral fins and of the pelvics with their associated claspers were still attached to the carcase, giving the appearance of fore and hind limbs. Such a monster was found stranded at Stronsay in the Orkney Islands at the beginning of the nineteenth century, and was actually described as an unknown species of animal in a learned journal under the imposing name of Halsydrus pontoppidiani. In this case, however, a few of the bones were preserved, and on subsequent investigation these were shown to be vertebrae of a large Basking Shark. Especially interesting features of the Basking Shark are the minute teeth, the very large gill-clefts, and the curious rakers on the hoop-like gill-arches — features which are found in only one other shark, the Whale Shark already mentioned. These 22 GIANT FISHES rakers, each of which is from 4 to 6 inches long, are closely set in a row on each gill-arch, and, as they project across the internal clefts leading into the gullet, they form a very effective sieve or strainer. Their microscopic structure is very similar to that of the teeth. In appearance they recall the baleen plates of the whalebone whales (see p. 203), and have an exactly similar function. Indeed, they provide an excellent example of what is known to scientific men as parallelism : that is to say, the evolution in totally unrelated groups of animals of similar structures designed to serve the same ends. It was the fancied resemblance of the gill-rakers to the whale- bone plates that led the older whalemen to call this shark the " Bone Shark ", a name still in use in some parts of the world. A study of the normal food of the Basking Shark gives a clue to the meaning of these structures. The diet consists almost entirely of small shrimp-like crustaceans, together with other minute creatures that swarm near the surface of the sea and make up what is known as the plankton. The manner of feeding is simplicity itself, and the Basking Shark has no call to go in active pursuit of its prey like its fish-eating rela- tives. Swimming among a mass of plankton, with its large mouth wide open, the shark takes in quantities of water with the contained life. This water is forced out through the gill- clefts, leaving the food adhering to the inner walls of the gullet and to the sieve-like gill-rakers, where it can be swallowed at leisure. The water which passes over the gills serves to oxygenate the blood, so that the Basking Shark may be said to feed and breathe by one and the same action ! Nothing is known of the breeding habits of the Basking Shark, but it is assumed to be viviparous like the other members of the family. Very young specimens have never been seen, and it is probable that these stay in deep water until they grow to a fair size. Small individuals, 10 to 15 feet in length, are sometimes captured, however, and differ markedly from the adults in the shape of the head. The fore part of the head is considerably drawn out, and forms a thick, pointed, fleshy snout, the tip of which is produced into a curved, soft hook. The flesh is of little value as food, and the Basking Shark cannot lay claim nowadays to be of much economic value. SHARKS 23 It has, however, an enormous liver, which yields a large quantity of oil, which can be used for tanning, for tempering steel, and for other purposes. Individual sharks yield from 80 to 200 gallons of oil, with an average of 125 gallons, and there is a record of 400 gallons from a single liver. At one time there was a regular fishery for Basking Sharks off the coasts of Norway, Scotland and Ireland, while it is said to have been hunted to a somewhat lesser extent on the coast of Massa- chusetts in America. The method of hunting was much the same as that employed for Whales, individual sharks being harpooned from a small boat. As the sharks tended to become less abundant, probably as the result of their wholesale slaughter, and as the commercial value of the oil gradually declined, these fisheries slowly died out. The methods employed in hunting the Basking Shark on the west coast ol Ireland were illustrated in an interesting and picturesque manner in the film " Man of Aran ", which met with such well-deserved success in recent years. Mr. Couch, writing in 1877, gives a detailed and vivid account of the hunt : " The boat . . . approaches the fish with a man in the bow ready to harpoon it ; the line attached to the harpoon is 200 fathoms long, and is coiled up in the bow ; a man stands by with a hatchet, ready to cut it, should it get entangled or foul of anything in running out. When the fish is struck, he will at the first dart carry out from 70 to 150 or 200 fathoms of line ; he makes this rush to the bottom, where he rolls himself, and rubs his wound against the ground to free himself from the harpoon. The fishermen generally allow him an hour to tire himself before they begin to haul upon the harpoon line ; they coil up the slack of it again, ready for him to make another rush, and play him in this way, sometimes for eight or nine hours, before they can get him to come to the surface ; and when he does so they are ready to strike him with two or three more harpoons ; and when these are fixed in him, they are able to pull him alongside the vessel with the harpoon lines ; they then stretch him fore and aft along the vessel's side, and get a jowl rope round his head, and the bight of a hawser round his tail ; they then give him two deep cuts, one on each side of the tail with a hatchet. In his agony and his efforts to get free, he works his tail so hard, that 24 GIANT FISHES he snaps the bone across where the cuts were made ; they then cut flesh holes in the body of the fish on both sides, that will take a large rope through them ; they then reeve ropes through these holes, and by hauling taut on the side of the fish next the vessel, and slacking away rope to the other side of the fish, it will cant him over on his back. They then split down the stomach, take out the liver, which is the only part they use for oil, and let the rest of the fish go adrift." " . . . These fish are most powerful in the water, and if harpooned in the shoulder they are very hard to kill, often carrying off the whole harpoon line , but experienced har- pooners strike them in the body near the dorsal fin, rather low down, where it will go through into the intestines, or near the vertebrae towards the tail. They must be struck with great caution, as they will stave in the boat with a blow of their tail, if it is at all within their reach." The shark is apparently quite indifferent to the approach of a boat, and a clever harpooner is sometimes able to place his weapon quite, close to the snout, thus preventing the fish from diving before other harpoons can be brought into play. A lean fish is said to hold out for a much longer period than a fat one. THRESHER OR FOX SHARK. (Genus Alopias.) Fig. 15. Similar in form to the Porbeagles, but easily distinguished by the very long tail, which is as long as the head and body together, and gently curved rather like the blade of a scythe. The tail is not provided with a keel. The snout is short and blunt. The teeth are small, flat, triangular, and with smooth edges. The external gill-clefts are only of moderate size. The pectoral fins are long and sickle-shaped. The coloration is dark greyish-brown to nearly black on the back and upper parts of the sides, changing somewhat abruptly to the white of the lower parts ; the lower sides of the pectoral fins and a space below the gill-openings are leaden in hue. Grows to a length of 15 to 20 feet, and a weight of nearly 1000 lb. There is probably only one species of Thresher {A. vulpes), SHARKS 25 which is found in most subtropical and temperate seas, being especially abundant in the Mediterranean and Atlantic. A Japanese writer has recently described two forms to be found in the seas around Formosa, distinguished principally by differences in the shape of the caudal fin, the size of the eye, and the proportions of the tail and body, but it seems possible that these are only varieties of the same species, the one with the larger eye inhabiting deeper water or even living near the sea bottom, and the one with the smaller eye living at the surface. The Thresher is one of the commonest of the larger sharks found on the British coasts. This is a rather formidable looKing shark, although quite harmless to man. It is a great nuisance to fishermen, as it not only destroys their catches, but also becomes entangled in their nets with disastrous results. It is a speedy surface swimmer, feeding almost exclusively upon fishes, especially herring, shad, pilchard and mackerel. In obtaining a meal the Thresher sometimes makes use of a curious and unique method, swimming round and round a shoal of fish in ever- decreasing circles, lashing the water with its tail, and thus driving the prospective victims into a compact mass, when they form a comparatively easy prey. Sometimes a pair of sharks will combine in carrying out this organized method of feeding. Mr. Coles has described one which was feeding in shallow water on the coast of Carolina, which was " throwing the fish to its mouth with its tail, and . . . one fish, which it failed to seize, was thrown for a considerable distance, clear of trie water ". A Thresher taken in the trawl in the Firth of Forth had half a bushel of garfish in its stomach — a good example of its voracious appetite ! Stories of Threshers attacking whales in league with swordfishes are probably without founda- tion, and may be due to faulty observation, the shark being confused with the Killer Whale. Its mouth and teeth are both far too feeble for the achievements in this direction that have been ascribed to it. The breeding habits of the Thresher are unknown, but the young are believed to be born during the summer. It is of practically no economic value, although the Chinese and Japanese make some use of it. Dr. Day reports that the Greek fishermen are said to have sought the Thresher for food, 26 GIANT FISHES and that a certain Dr. Caius, in 1569, " compared its flesh to that of the salmon, but admitted it was not quite so agreeable to the palate ". The names Fox Shark and Whip-tailed Shark probably refer to the length of its tail, while such popular names as Thresher, Thrasher, Swingletail, Swiveltail, etc., have reference to the peculiar method of feeding. The generic name, Alopia$, is the Greek word for a fox, and the trivial name, vulpes, is the Latin word for the same animal. CHAPTER II : SHARKS {continued). Orectolobid Sharks. Nurse Sharks. Whale Shark. Wob- begongs or Carpet Sharks. Zebra Shark. Requin Sharks. Blue Sharks. Tiger Shark. Topes. Hammer-head Sharks. Spined Sharks. Greenland or Sleeper Shark. Bramble or Spinous Shark. Angel- or Monk-fishes. ORECTOLOBID SHARKS. (Family Orectolobid.^.) Related to the Sand Sharks (Odontaspidae), but distin- guished from them by having grooves connecting the mouth with the nostrils, and by the position of the last 2 to 4 external gill-clefts, which lie on either side above the base of the pectoral fin. The two dorsal fins are placed well back on the body, the first being above, a little in front of, or behind the level of the pelvic fins. This family includes a number of different looking Sharks, some large, others quite small. All are found in tropical and subtropical seas. Fossil remains of Sharks believed to belong to this family date back to the Jurassic period. 28 GIANT FISHES NURSE SHARKS (Genus Ginglymostoma.) Fig. 16. The body is long and nearly circular in cross-section, and the tail is long and bent upwards at its base. The head is short and blunt, and the snout does not project much beyond the straight mouth. The eyes are small and without folds below. There are several rows of small teeth in each jaw, all or most of the rows being in use at one time (Fig. 59) ; each tooth has 3 or more points. The spiracles are small and situated behind the eyes. The external gill-clefts are of moderate size, the last 2 close together, and the last 2 or 3 above the base of the pectoral fin. The second dorsal fin is above or partly in front of the anal, which is quite free from the caudal fin, the lower lobe of which has a small notch. The coloration is more or less uniformly brownish, but young individuals often have small, scattered round black spots. Grow to a length of 6 to 12 feet. The Common Nurse Shark or Gata (G cirratum) is found in the tropical Atlantic and on the west coast of Mexico. Other species occur in various parts of the Indian and Pacific Oceans. The Nurse Sharks are shore-dwelling creatures, and the common species is abundant in the comparatively shallow water round Florida Keys and in the coral reefs of the West Indies. They are sluggish and quite inoffensive, and may often be observed basking in the sunshine in small groups, or nosing about in search of food among masses of seaweed or pieces of loose coral. At times they lie in water so shallow that their dorsal fins project above the surface, and they have been known to allow a boat to bump into their heads before moving away. These sharks have a varied taste in food, including such diverse creatures as small fishes, squids, cuttlefishes, shrimps, lobsters, crabs, sea-urchins and shellfish in their diet. An American author has described them as looking like " well-fed pigs in a barnyard ", and adds that " there is no more sport in harpooning or hooking one than in doing so to a fat pig ". " So harmless, so sluggish and so lacking in fear are these SHARKS 29 sharks," writes Dr. Gudger, " that they may rather easily be driven into shallow water and caught without harpooning. . . . My men used to drive them into shallow water, catch and drag them up on the beach, and after 1 had finished measuring and examining them, put them back into the water." In their breeding the Nurse Sharks are ovo-viviparous ; that it to say, the eggs are shed from the ovaries, passed into a shell-gland where they are enveloped in a brownish-black horny case, and then lie in the lower part of the oviduct (the passage leading from the ovary to the exterior) until the young are finally hatched by the breaking of the shell. It is probable that the ancestors of these sharks produced eggs, which were deposited in cases in the open sea like those of the Dogfishes, and that to-day they are on the way to becoming viviparous, but still retain the egg-capsule within the body of the mother. The skin of the Nurse Sharks, with its very small, close- set, tile-like denticles, is said to provide a particularly good shagreen. They seem to have little other economic value. The name " nurse " would seem to be a contemptuous epithet, and to refer to the ease with which they may be cap- tured. "Nurse" or "Nusse" is also an ancient term for a large fish. As early as 1699 we find in Dampier's ' First Voyage to Campeachy a reference to " sharks, sword-fishes, and nurses ". Dampier states that " the Nurse is just like a Shark, only its skin is rougher, and is used for making the finest Rasps ". The scientific name, Ginglymostoma, is derived from two Greek words meaning " hinge " and " mouth ". WHALE SHARK. (Genus Rhineodon.) PL II a. A very large Shark, with a long, nearly cylindrical body, and a broad, blunt head. The upper part of the body is provided with curious keels or ridges, running lengthwise, one along the middle line of the back and 2 or 3 on each side. The eyes are small and without folds below. The large straight mouth is nearly at the end of the head, and each of the jaws is armed with a band of numerous, very small, curved teeth, forming a kind of rasp. The spiracles are small and are placed 30 GIANT MSHES behind the eyes. The external gill-clefts are wide, and the last two on each side are placed above the base of the pectoral fin ; the gill-arches are provided with long, close-set gill-rakers as in the Basking Shark {Ceiorhinus). The second dorsal fin is above the anal, which is quite free from the caudal fin. The caudal fin itself has a well-developed lower lobe, without a notch, and, as the axis of the fin is bent strongly upwards, it appears almost symmetrical. The pectoral fins are large and somewhat sickle-shaped. The general coloration is brownish or greyish, becoming paler on the lower parts, and the head and body are covered with round white or yellow spots ; on the head the spots are smaller and much closer together, giving it a marbled appearance, while on the body they are separated by narrow vertical streaks of the same colour. Grows to a length of at least 50 feet and a weight of several tons. The single existing species (R. typus) is found in the warmer parts of the Atlantic, Indian and Pacific Oceans. This enormous surface-swimming Shark may be readily distinguished from all other forms of the open sea by its striking colour pattern. It was first discovered in 1S28, when a specimen was harpooned in Table Bay, South Africa, and examined by Dr. Andrew Smith, an army surgeon, and a keen student of South African fishes. He published the first scientific description of the Whale Shark, but it was not until twenty years later that his figure of the Shark appeared. Dr. Smith records that the skin of this specimen was purchased for £6, and was forwarded to the Natural History Museum in Paris. Since that time a number of individuals of varying sizes have been washed ashore or harpooned in different parts of the world, but mounted skins are still rarities in museums. A 38-foot specimen captured in Florida waters in 1912 caused so much interest that it was skinned and stuffed and then carted round the principal towns of the eastern United States. In spite of its huge bulk, it is quite inoffensive, and the only danger to be apprehended from the largest Whale Shark is an accidental bump of its head or body against the side of a small boat or a blow from its powerful tail. Like the Basking Shark it can be easily approached and harpooned, but on being wounded it will either dive straight down or set off at SHARKS 31 a high speed, dragging the boat behind it. Its staying powers are remarkable, and several hours may elapse before it finally succumbs. On more than one occasion a Whale Shark basking at the surface has been rammed and nearly cut in two by a large vessel. It is believed that when once lanced or harpooned the Shark will in some way contract the muscles of the back, and in this manner try to prevent the entrance of another weapon. In many respects the Whale Shark recalls the Basking Shark of our own seas, dealt with in the previous chapter. There is the same bulk, tiny teeth set in a huge mouth, long, close-set gill-rakers, wide external gill-clefts, and keeled tail with apparently symmetrical fin. Indeed, some authorities are inclined to place the two forms close together, but others are of the opinion that these resemblances have been brought about by the adoption of similar modes of life, and particularly of similar methods of feeding, and do not indicate actual relationship. Our knowledge of the anatomy of the Whale Shark is not yet complete, but it would seem to be more closely allied to the Orectolobid Sharks. It is of some interest to note that the curious ridge-like keels along the body also occur in the Zebra Shark and in other members of this family, but not in any other Sharks. Like the Basking Shark the Whale Shark feeds on small crustaceans and other planktonic creatures, which it strains from the water by means of the sieve-like gill-rakers. So huge is its mouth, however, that other objects may enter on occasion, and it is recorded that an individual caught in the Philippine Islands had swallowed a number of shoes, leggings, leather belts, etc., and another from Japan had a fragment of an oak pole, about a foot long, in its stomach ! Nothing at all is known of its breeding habits, but it is almost certainly viviparous. It appears to have no economic value, although the liver might be expected to yield an oil of commercial importance. The Whale Shark is known by a variety of names in different parts of the world, of which " Chagrin " (Seychelles), " Tiburon ballenas " (California), " Tintoreva " (Gulf of Panama), "Chacon" (Philippines), and " Mhor " (Karachi) may be mentioned. The name Whale Shark may refer to its size, 32 GIANT FISHES Fig. 16. — Common Nurse Shark or Gata (Ginglymostoma cirratum) Fig. 17. — Wobbegong or Carpet Shark (Orectolubus barbatus). ps^g? Fig. 18. — Zebra Shark (Stegosioma ligrinum). SHARKS 33 but more probably to the baleen-like gill-rakers. The scientific name, Rhineodon, is derived from the Greek words for " file " and " tooth ", and refers to the rasp-like tooth bands. WOBBEGONGS OR CARPET SHARKS. (Genus Orectolobus.) Fig. 17. The body is thick-set and its front part is more or less flattened ; the head is broad and flat, with a very blunt snout. The sides of the head, and often the chin as well, are provided with tassels of skin. The eyes are small and are provided with folds below. The mouth is wide, nearly straight, and is situated almost at the end of the head ; it is armed with slender, pointed teeth, of which those in the centre are larger and with a single point and those at the sides smaller and with some additional points. The spiracles have the form of wide, oblique slits, situated behind and below the eyes. The external gill-clefts are of moderate size, and the last 3 or 4 on each side are above the base of the pectoral fin. The second dorsal fin is about as large as the first, and is placed in front of the anal, which reaches to or is actually joined at its base to the lower lobe of the caudal fin. The caudal fin is moderately long, with a straight axis, and there is a notch in the hinder part of the lower lobe. The pectoral fins are broad and often rounded. The coloration is very variable, the ground-colour being yellowish, greyish or brownish, and variously marbled, spotted, barred or striped with paler and darker. The larger species grow to a length of 6 to 8 feet or even more. There are about five species, occurring on the coasts of China Japan, eastern and southern Australia. The flattened, thick-set shape, the curious tassel-like appendages on the blunt head, and the mottled coloration, give these Sharks an appearance very different from any so far considered. When the mode of life, however, and especially the manner of obtaining food is considered, the meaning of these features becomes clearer. Instead of going in active pursuit of prey like a Blue Shark, a process associated with a 34 GIANT FISHES slender, streamlined, uniformly coloured body, or gulping down large masses of planktonic life like the Whale Shark, the Carpet Sharks rely on cunning to obtain their meals, and make use of less strenuous but none the less effective methods of feeding. A Carpet Shark spends most of its time on or near the sea bottom, lying motionless among rocks and weeds or half buried in sand or mud, until such time as a prospective victim — a fish or crustacean — comes within reach of the jaws. It is not built for speed, but any loss of swimming power is amply compensated for by the remarkable resem- blance of the Shark to its surroundings. When at rest it looks for all the world like a rock or stone overgrown with seaweed, and the flaps of skin on the head and round the mouth, waving gently in the water or lying spread out on the sand, enhance the deception, and at the same time help to break up the outline and render the Shark less conspicuous. As a general rule Carpet Sharks are quite harmless, but they will snap viciously when caught and have been known to attack persons wading in shallow water. Little is known of their breeding habits, but they are ovo-viviparous like their relatives the Nurse Sharks. A large number of young is produced at a single birth. The small rough denticles in the skin, and its handsome varie- gated pattern, makes it a favourite shagreen for decorative purposes, and there is in consequence a considerable demand for these Sharks. They have little or no value as food. ZEBRA SHARK. (Genus Stegostoma.) Fig. 18. The body is long, with its hinder part flattened from side to side ; the head is short and blunt. There are some ridges or keels running lengthwise along the back and sides. The eyes are small and without folds below. The mouth is straight, and is provided with many rows of small teeth, each of which has 3 points. The spiracles are of moderate size and are situated behind the eyes. The external gill-clefts are fairly large, and the last 3 on each side are above the base of the pectoral fin. The second dorsal fin is rather smaller than the first, and is placed partly above and partly in front SHARKS 35 of the anal, which just reaches the caudal. The caudal fin is very long, with a straight axis, and with a notch in the hinder part of the lower lobe. The pectoral fins are broad. The general coloration is yellowish-brown, ornamented with many vertical series of rounded dark spots ; the young have a very different pattern, with broad dark brown cross-bars with black edges, separated from one another by narrower interspaces of pale yellow. As the fish grows up the bars gradually become paler and dark spots appear on them, while the dark edges of the cross-bars break up into spots. Grows to a length of 6 feet or more. The single existing species (5. tigrinum) is widely distributed in the tropical parts of the Indian Ocean, East Indian Archi- pelago, and Chinese Seas, and occasionally strays southwards to the coasts of Australia. This handsome shore-dwelling Shark is quite harmless, and feeds mainly upon shellfish and crustaceans. Little is known of its habits. It produces eggs, that are deposited close to the shore. Apart from the use of its skin as shagreen, it has little economic value. REQUIN SHARKS. (Family Carcharinid.e.) Sharks with a long body and somewhat flattened tail. The snout is more or less pointed, flattened above, and projects above the crescent-like mouth. The eyes are each provided with a third eyelid, or nictitating membrane, that can be drawn up across the eye from below. There are no grooves connecting the mouth with the nostrils. The spiracles are small or absent altogether. The last i or 2 external gill-clefts on each side are above the base of the pectoral fin. There are two dorsal fins, without spines, the first of which is usually placed in front of the pelvic fins ; there is a single anal fin. This is the largest family of existing Sharks, and its members are found nearly all over the world. The family is a compara- tively modern one, as fossil remains, mostly teeth, do not occur in rocks older than those of the Eocene period. All the Requin Sharks are viviparous or ovo-viviparous. 36 GIANT FISHES BLUE SHARKS. (Genus Carcharinus.) PI. II b ; Fig. 19. The teeth either stand erect or are set obliquely in the jaws; each tooth has a single, strong, sharp point, which is either smooth or finely saw-edged (Fig. 59). There are no spiracles. The second dorsal fin and the anal fin are both very small. There is a pit at the root of the caudal fin, which has a distinct lower lobe. The coloration is always uniform, and is usually grey or bluish-grey on the back, shading away to white on the lower parts ; in certain species some or all of the fins are tipped with black. The largest species (Great Blue Shark) grows to a length of 25 feet or more ; many others attain to a length of 10 to 15 feet. This is a large genus of Sharks, containing many species, and some authorities group these into four or more distinct genera or subgenera, distinguished from one another mainly by the size and character of the teeth. Blue Sharks are to be found in almost all tropical and subtropical waters. The Great Blue Shark (C. glaucus) is cosmopolitan in its distri- bution, and small individuals are not uncommon on the British coasts ; the Black-finned or Black Shark (C. melanop- terus) occurs in the Indian and Pacific Oceans ; the Dusky Shark (C obscurus) is found in the North and Middle Atlantic : and the Cub Shark or Requiem (C. lamia) abounds in the Mediterranean and in the tropical parts of the Atlantic. These are four of the better-known species. The Zambesi Shark (C. zambesensis) , which has been captured 120 miles from the iiver mouth, and the Ganges Shark (C. gangeticus), common in the Ganges, Tigris and other large rivers, are examples of species that habitually entei rivers. One species (C. nicara- guensis) is unique among Sharks in being confined entirely to fresh water, and is found only in Lake Nicaragua and its outlet the Rio San Juan. These Sharks, as their lithe, streamlined bodies and uniform coloration suggest, are mostly dwellers in the open sea, and pass a roving, predatory life in the upper layers of the water. Whether disporting themselves at the surface in the sunlight, SHARKS 37 or swimming aoout in shallower water, often quite close to the shore, they readily catch the eye. Nearly all the sharks described in books of travel belong to this genus, and those observed by the voyager following in the wake of a vessel are almost always Blue Sharks. They have more than once been compared to hungry dogs in search of food when seen from the deck of a ship, and they well merit the names of " wolves of the sea " or " chien de mer " that have been bestowed upon them. The Great Blue Shark visits the coasts of the British Isles during the summer months, and small individuals may be seen on calm, warm days swimming lazily near the surface, often with the tail and the tips of the dorsal fins projecting from the water. When in pursuit of prey, or when otherwise excited, they have been observed repeatedly to cover and uncover their eyes with the third eyelids, and it seems that this is a kind of " blinking " caused by the irritation of the intense light. At night their activity is greatly increased, and at such time they hunt their prey mainly by scent. The tiny pores with which the surface of the snout is pitted probably serve some sensory function. The Blue Sharks are both fierce and voracious, and their appetite^ are well nigh insatiable. Other fishes form the principal food, and they may even include their own kind in their dietary, but no kind of animal food, whether alive or dead, comes amiss to them. The larger species of the op