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Home , Atlantic stingray, Atlantic torpedo, Butterfly ray, Chimaera, Chimaera (genus), Diamond stingray

SHARKS, SKATES, RAYS, AND

UNITED STATES DEPARTMENT OF THE INTERIOR AND WILDLIFE SERVICE BUREAU OF COMMERCIAL

Circular 228 TABLE 1. -- tiximum sizes of camnon of

Species Traditional Mucimum length Muimum length maximum size (measure

SixgL. st.ark .... 1 sp. .•..•••••••. 15 feet 5 inches 26 feet 5 inches

nd hary...... taurus...... 10 feet 5 inches 12 feet 3 inches 15 feet 11 inches

Porbeagle •...... 1 LamTUl TUlSUS...... 10 feet 12 feet 12 feet

Sall10n . .... LamTUl ditropis ...... 8 feet 6 inches 8 feet 6 inches 12 feet

L 0 .•.••.•.•.... oxyrinchus ...... 10 feet 6 inches 12 feet 12 feet - 13 feet

'hi te sr.ark...... Carcharodan carcharias. . . 18 feet 2 inches 21 feet 36 feet 6 inches

Basking shar".... Cetorhinus maximus ...... 32 feet 2 inches 45 feet 40 feet - 50 feet

Thresher shark... Alopias vulpinus ...... 18 feet 18 feet 20 feet

rse shark...... Ginglymostoma cirraturn.. 9 feet 3 inches 14 feet

Whale shark...... Rhincodan typus...... •. 38 feet 45 feet 45 feet - 50 feet

Olain dogfish.... retifer...... 1 foot 5 inches 2 feet 6 inches

Leopard shark.... semifasciata...... 5 feet 5 feet

Smooth dogfish ... Alustelus canis ...... 4 feet 9 inches 5 feet rieer shark...... Galeocerdo cuvieri...... 13 feet 10 inches 18 feet 30 feet

Soupfin shark.... Galeorhinus zyopterus . . .. 6 feet 5 inches 6 feet 5 inches 6 feet 5 inches

Blue shark...... Prionace glauca ...... 11 feet 12 feet 7 inches 25 feet

Bul .. shark...... leucas...... 9 feet 10 inches 10 feet

Whi tetip shark. .. Carcharhmus longimanus .. 11 feet 6 inches 12 feet

Sandbar shark.... Caycharhinus milberti. . . .. 7 feet 8 inches 8 feet

Dusky soork...... Carcharhinus obscurus . . . . 11 feet 11 inches 15 feet

Bonn thead...... phyrTUl ttburo ...... 3 feet 7 inches 6 feet

Cr at hrum.erhead . Sphyrna mokarran ...... 18 feet 4 inches 15 feet

iny 0 fish.... Squalus acanthias ...... 5 feet 3 inches 5 feet I I n d fish .... 1 virens...... 0 feet 11 inches I ~d at r d fish. ep ••...••...•.. 0 feet 7 inches

nland shar .. Sommosus microcephalus. 16 feet 6 inches 21 feet 24 feet

r ...... 1 PrtStiophorus schroederi . 2 feet 10 inches

shark .••... , Squatrna dumerill ...... 4 feet 5 inches DEPARTMENT OF THE INTERIOR Stewart L. Udall, Secretary Johll A. Carver, Jr., Under Secretary Stallley A. CHin, Assistant Secretary jor F~sh and Wildlife FISH AND WILDLIFE SERVICE, Clarence F. Pautzke, Commissioner BUREAU OF COMMERCIAL F:SHERIES, Donald L. McKernan, Director

Sharks, Skates, Ray, and Chimaeras

By

J. R. Thompson

Stewart Springer

Circular ll8

Washington, D.C.

September 1965 CONTENTS

Page

Introduction...... 1 Class , the cartilaginous ...... 2 Sharks...... 4 Skates and rays...... 10 Chimaeras ...... 14 Annotated list of references...... 16

ILLUSTRATIONS

" tree" of the illustrating, in the opinion of many zo- ologists, the relations existing among member s of the group...... 2 A from the Gulf of and her litter. Few sharks produce this many young at one .. ime...... 4 A "typ1cal" shark, l11ustrating terms used in description...... 5 Top: A small shark, Squalus cubensis, from the . Many species of sharks are many times smaller than this species. Bottom: A large Silky shark, Eulamia floridana, taken on a longline. These large, oceanic sharks sometimes reach lengths of about 10 feet...... 6 A small , Alopias vulpinus. A 14-foot specimen of this species, recently taken was estimated to weigh aPfroximately 500 pounds and possessed a caudal lobe measuring 7z feet. The long caudal lobe 1S apparently used to stun prey...... 9 Removing the from a large silky shark...... 10 A generalized illustrating terms used in descnption...... 11 A "typical" ray, the roughtail , centroura. This specUne.n measured 62 inches across the fins and weighed 285 pounds. Such rays are taken frequently in trawl drags along the east coast of the United States...... 13 A generalized illustrating terms used in description...... 14

iii SHARKS, RAYS, SKATES, AND CHIMAERAS

By

J. R. Thompson and Stewart Springer

INTRODUCTION

Sharks, skates, rays, and, to a require special collecting and handling lesser extent, chimaeras--all grouped techniques. They are diificult to keep in by zoologists in the single captivity, and their collection and study class Chondrichthyes (cartilaginous as living is quite expensive. fishes)--have been the subjects of in­ But over the years, zoologists have tere st for many year s . On the negative succeeded in amas sing sufficient data side, the interest in many of these to outline, in greater or les ser detail, fishes has arisen largely from fear-­ the characteris~ic s and habits of many fear of injury to fishermen and of the cartilaginous fishes . swimmer s, fear of damage to fishing gear and equipment, and the fear that This paper has been written as an is a natural accompaniment of a lack of introduction to the members of the class knowledge. On the positive side, the Chondrichthyes . The information con­ interest has arisen as a result of at­ tained has been drawn from the litera­ tempts to turn some of these fishes ture, from zoologists and fishermen of to economic advantage, and out of man's many countries, and from the personal innate curiosity concerning the world experiences and observations of the around hlm. authors . The purpose of the paper is to answer the man y general questions Despite widespread lnterest, ac­ asked z oologists each year cumulation of adequate knowledge con­ concerning sharks, skates, rays, and cermng sharks and theIr close relatives chimaeras, o r if not to a nswer, at has been slow, and a large body of least to suggest further, m o re detailed speculation and "old wives' tales" has sources of information. Toward this arisen as a result of attempts to £111 end, the text has been kept brief and in the gaps . Obstacles to the study of general, and an annotated list of ref­ cartilaglnous fishe s are many. Most erences has been included. In most of these fishes are pelagic, and many cases, the r e ader who is sufficiently of them inhabit the open water s of the interested to pursue the subject beyond high where large ocean-going the confines of this circular will find vessels are needed for their study. more material in the references listed. Many species are confined to relatively He may also find clues to further re­ great depths where collection is dif­ search sources in the bibliographies ficult and expensive. Even those species contained in the references examined. that inhabit shallower, coastal water s To facilitate use, the references are listed by topic in an arrangement Note.--J. R. TIlOmpson. Fishery Biologist(Research). roughly paralleling the arrangement Bureau of Commercial Fisheries Exploratory Fishing Base. Pascagoula. Miss •• and Stewart Springer. Fishery Biologist of the subhec1dings of the text. (Research). Bureau of Commercial Fisheries Ichthyological Field Station. Stanford. Calif. Terms commonly applied to car­ tilaginous fishes and other large marine

1 creatures are frequently subject to the Greek words elasmo, mea n i n g confusion. Scientific names of Greek platelike or s 1 it 1 ike, and branchia, or Latin derivation are frequently re­ meaning ) which has corne into duced to English form and used as common usage and which refers to any English common names. Chimaera is shark, skate, or ray, but not to chi­ such a name (derived from the Greek maeras. The anglicized word selachian chimair, meaning goat), and it is useful (from the Greek term coined to de sig­ because it covers all one closely re­ nate fishes having cartilaginous skele­ lated group of cartilaginous fishes in­ tons instead of bone) has become even cluding some known as ratfishes, some more restrictive and now refers as elephant fishes, and others. Elasmo­ onl y to s h ark s, not to s kat e s or branch is another word (derived from rays.

CLASS CHONDRICHTHYES, THE CARTILAGINOUS FISHES Member s of the c 1 ass Chon­ which are composed of rather drichthyes, the sharks, skates, rays, than true bone, a feature which sets and chimaeras, possess well-developed them apart from the bony fishes and lower jaws which set them apart from other higher vertebrates. The car­ the lampreys, hagfish, and other lower tilaginous skeletons, however, are often vertebrates; and theypossess skeletons made up of structural components that

AMPHIBIA

CHONDRICHTIITES (Cartilaginous fishes) OSTEICHTlIYES (Higher bony fishes)

PLACODERMI (Archaic: jawed fishes)

AGNATHA (Jawless fishes) + NON·VERT£BRAT£ CIIORDAT£S

. 'Family tree" of the vertebrates illustrating, in the opinion of many zoologists, the relations existing among members of the group. are so stiffened with mineral deposits Skates and rays have a more-or­ that microscopic examination and a less flattened appearance. and all ex­ k now led g e of the developmental cept a few are either wholly or partially processes involved in cartilage and covered with denticles or spines. which bone formation are necessary to deter­ may be scattered irregularly or ar­ mine that cartilage. not bone. makes ranged in definite patterns. All skates up the skeletons. For this reason. we and rays have five gill slits on each often speak of the "backbone" of a shark side of the lower surface of the head­ when referring to the hard. cartilagi­ neck region. nous (but bonelike) vertebrae that com­ prise the structure that places the Chimaeras. like sharks. are fusi­ members of the class Chondrichthyes form in shape. Unlike sharks. they in the Vertebrata . are usually smooth skinned. although a few denticles appear on the young records of primitive fishes and may per sist in some adults. and ancestral to pre sent-day s h ark s. they have only one external gill open­ skates. rays. and chimaeras. date back. ing on each side. perhaps a quarter of a billion years. to the period (mid-Paleozoic Although some sharks and rays era) . Moreover. representatives of all enter for short periods. of the presently existing families of and a few customarily enter fresh water cartilaginous fishes have been found in to give birth to their young. most the fossil deposits of the early Ter­ species are exclusively marine. One tiary period (early Cenozoic era)-­ species of shark is said to be es­ good evidence that these fish families tablished as a permanent resident of have been on earth at least a thousand Nicaragua. but this is exceptional. times longer than the human family. Most chimaeras inhabit deep water. This long geological history also indi­ and all live in strictly oceanic environ­ cates that the cartilaginous fishes can ments. maintain themselves successfully in spite of changing environment and vary­ Reproductive processes are ex­ ing conditions of competition. and that tremely variable in the class Chon­ they have been remarkably stable (in drichthyes. Many members of this the biological sense of resistance to class are ovoviviparous and bring forth evolutionary change) since at least the livin g young that have been hatched Tertiary period . from inside the ovi ducts of the mother . Once hatched. the Zoological definitions adequate to are nourished in a variety of ways . set off the classes of vertebrates from Some members are VIVIparous , or one another with precision. or to define nearly so, and bring forth living young the subdivisions of cartilaginous fishes. that have bef'n nourished by substances are necessarily long. To find the de­ in the mother's blood stream trans­ tailed and exact definitions required for ferred to the developing through taxonomic work. the reader is referred a . Some are oviparous and lay to one or more of the appropriate cita­ s enc a sed in horny or leathery cap­ tions at the end of this circular. For sules. which are deposted on the ocean general purposes. the following re­ floor. Regardless of the developmental marks should be sufficient to separate process, the number of eggs produced the major groups: by a single cartilaginous fish is very Sharks usually have the shape of a small compared with the number of eggs "typical fish"--a fusiform shape--and produced by a single bony fish. But the most of them are densely covered with cartilaginous fishes are able to main­ small. toothlike scales called denticles tain their numerical status quo. because which give the skin its rough sand­ their young. at birth or hatching, are paper like feeling. In addition. all sharks much larger than the newly hatched have from five to seven gill slits or young of most kinds of bony fishes and external gill openings on each side of are, therefore. better able to defend the head or neck. themselves against predators. A

3 A great hammerhead from the Gulf of Mexico and her litter. Few sharks produce this many young at one time. greater proportion of young cartilagi­ much greater when fertilization i s in­ nous fishes reach maturity for that ternal than when it i s external as with reason. most bony fishes. Male chondrichthoid fishes are easily recognized by the Fertilization is internal throughout presence of a pair of intromittent the clas s. Internal fertilization is organs called clasper s that arise from another mechanism by which the car­ the inner margins or bases of the tilaginous fishes make up for the small pelvic fins and usually extend beyond number of eggs produced. The chances the tips of the fins in mature cartilagi­ of the eggs becoming fertilized a:re nous fishes.

SHARKS Numbers and General water realms which have not been Distribution thoroughly investigated. An estimated 300 species of sharks are recognized in the world today. In A few species, including the Green­ several instances, especially among land shark and the Pacific sleeper the larger, far-ranging species, we shark, inhabit very cold seas, but the have probably described the same variety and number of sharks are sharks under more than one name. greater in tropical and subtropical There are, however, undoubtedly other waters. Sharks are present in greater species existing that hav.e not been given variety, and probably also in greater names as yet, particularly in the deeper abundance, in moderate depths--from sections of the ocean and in the mid- 50 to more than 500 fathoms. Some

4 c;0l Fin

Fins

Gill slits

ft ~ J~ Nostril r Pe lvic Fins [

Dorsal Fin ~th "

( Upper lobe, Co udal Fin

Anal Fin ~Lower lobe, Caudal Fin

A " typic al" shark, illustr ating terms used in description

sharks are found in much greater Size depths, although actual captures have not been made as yet in water s deeper A tabl e on the inside cover of this than 1,500 fathoms (9, 000 feet) . There circular lists the maximum :tecorded are also several species that inhabit lengths and weights of many of the very shallow waters along the coasts . common species of sharks. Sharks The se include some of the dogfishes, range in size from individuals that small blacktip sharks, hammerheads, nur se sharks, sand sharks, and sand­ mature at a total length of less than 1 bar sharks . foot to indi v i duals that do not mature until they are many feet long and that Abundance may reach lengths of about 45 feet. One of t he smalle st sharks k now n, Despite their appearance, at time..s, sp., lives only indeepwater in great concentrations, sharks are SquaUolus and apparently never reaches a length not normally abundant in companson much in excess of 6 inches . The little with many bony fishes. In the United green dog shark, States the spiny dogfish, one of the Etmopterus v ire ns , from the Gulf of Mexico, is full-grown smaller sharks, is common off the at a length of about 9 inches, and newly coasts of New England and the Mid~le born individuals are about 4 inches Atlantic States in the long. and off the coasts of Washington and Oregon in the Pacific Ocean. In these areas it is, at times, common enough The largest species, by weight, is to be a great nuisance to commercial the . Another large species, and sport fishermen. The larger sharks the , is somewhat less are less abundant. bulky, but about as long.

5

Most, or all, of the maximum exploratory research ve sse 1 Oregon recorded sizes contained in the table have confirmed this behavior. Whale refer ·to female sharks, and, indeed, sharks have also been observed to the females of all shark species studied drive tuna fishermen out of their fishing for this attribute average somewhat racks. But on the basis of accumulated longer with the average weight ap­ evidence, the whale shark is probably preciably greater than that of males. not ordinarily aggressive toward large On the Atlantic coast of the United creatures including man. It probably States, for example, adult male sand­ swallows large objects only if they are bar sharks vary from 5 feet 10 inches taken incidental to its regular feeding in length to 7 feet 4 inches, whereas activities. This, however, is sufficient female adults vary from 6 feet to 7 reason for treating these huge and feet 8 inches. This represents an powerful sharks with caution. average 5 percent longer length for the females, and this longer length is ac­ A few sharks, including the white companied by an average 25 percent shark and the . , normally greater weight. attack large and active prey. Other sharks, including the smaller hammer­ Food and Feeding Habits heads, and small blacktip sharks seem to prefer and small fishes. All sharks are primarily predators The tiger shark, which would normally in the sense that they all feed on be expected to obtain its food by active life. The variety of animal life con­ pursuit and capture of other fishes, sumed, however, is almost limitless, sometimes haunts steamer lanes to and nearly all sharks excepting perhaps gather in garbage. A large tiger shark, such forms as the specialized basking captured by the crew of the Oregon, sharks, are secondarily . contained not only food that had been Some sharks appear to be indiscrimi­ thrown overboard several hours ear­ nant in their feeding habits. Curiously, lier, but also tin cans and milk cartons. the largest known species feed on the Coastal fishermen frequently complain smallest prey, and some of the smallest about sharks of several species which sharks consume relatively large crea­ follow their vessels and tear up the nets tures. to obtain t he fish contained within.

The huge whale sharks and basking Large s harks such a s the white sharks are primarily filter feeders . shark, the dusty shark, and the white­ These sharks swim with their mouths tip eat porpoises 1 when they can cap­ open anq strain or filter out small ture them. Porpoises are much faster planktonic as the water, than sharks and can outrun them or coming in through the mouth, passes drive them away. If, however, a por­ over sievelike gill rakers and out poise is weakened through fatigue or through the gill slits. Examination of severe injury and is isolated, it may contents reveals that these meet a sudden end in an attack by large sharks filter great quantities of sharks. Observations, made from the small crustacea and minute fishes in Bureau's research vessel Oregon, have this manner, and such small prey con­ sub stantiated tale s of porpoi se s ac­ stitutes the primary source of food for tively driving sharks away from their them. On the other hand, there is little young and of schools of porpoises, the doubt that the whale sharks also, oc­ members of which would take turns casionally, consume larger pre y. driving off attacking sharks and rest­ Fishermen have reported that whale ing. At other times, however, porpoises sharks, feeding at the surface on great and sharks may even feed together on schools of small fishes, occasionally trash fish thrown from a boat, and the trap which are also feeding on porpoises apparently have sufficient the small fishes and which, in their lPorpoises are marine mammals. The term •'dolphin " quest for food, follow the small fishes is sometimes used for these animals. but "porpoise" is straight into the whale shark's mouth. probably preferable because "dolphin" is used also tode­ o b s e r vat s from the Bureau's note a bony fish commonly taken by sport fishermen.

7 confidence in their own speed and of the shark is de:­ strength that they do not waste energy centralized to a much greater extent attacking the sharks when the sharks than it is in the higher vertebrates, are not aggressive. and the areas of the brain usually re­ garded as thought centers are absent in sharks. Sharks have been shown ex­ Some of the smaller species, in­ perimentally to be capable of develop­ cluding the deep-water green dog shark, ing rather complicated responses to are thought by some to hunt in packs, conditioning stimuli and may t h us because their stomachs often contain be able to learn at the ref lex the beaks of and , repre­ level. senting prey too large and agile for these small sharks to kill and eat alone. Anatomical Features

Sensory Perception In addition to the general anatomi­ cal features described in the introduc­ Studies on sensory perception of tion, each species of shark has its own sharks have been difficult to carry structural adaptations. Many of these out satisfactorily. In the broad/est con­ features can be correlated with a more not-ation, the senses of sharks are or less specific way of life assumed by similar to those of other animals. The the shark species. A few examples of sense of smell is presumed to be highly divergence from the generalized developed and has been shown experi­ shark pat t ern and of adaptive fea­ mentally to playa major role in food tures can be given here, many more finding. Sharks also have a sense exist. corresponding to our sense of taste, but organs for t as tin g are widely The angel sharks, found on both scattered over the skin of the head and coasts of the United States, diverge even other parts of the body. Although from the typical fusiform shape and this sense is in some way related to display a flattened appearance char­ feeding habits, it is possible that in acteristic of rays. A second raylike sharks it serves other functions as well. shark, although not flattened, is the Sharks I eyesight is apparently adapted of the deep water s of the best for the detection of movement, but their are extremely complicated Straits of which resembles closely the of shallow coastal structures, adapting especially to low light levels. wa~er s. Sawfish, though sharklike, are true rays. In spite of the superficial resemblance to rays exhibited by Some sharks have cal car e 0 us these two shark species, close ex­ bodies in the chamber of the inner ear amination shows that the i r more which are presumed to be associated basic characteristics are tho s e of with the sense of balance. Sharks are sharks. responsive to noises and pressure waves, but the importance of sound and pressure differentials to sharks is The thresher shark has a pecul­ not well understood. Experimental pro­ iarly enlarged and elongated upper cedures to determine the roles of the caudal lobe which, according to fisher., ears (internal) and the men observers, it uses to stun its prey organs have met with only limited by "threshing" around in a school of success. fish. Its tail is one of the toughest flexible structures developed in the animal kingdom. Many other correla­ Sharks apparently have a very low tions between anatomy and mode of life intelligence level and many, if not all, can be pointed out. Fast- swimming, of their activities are reflexive. The oceanic sharks, such as the mako and

8 A small thresher shark, Alopios vulpinu$. A l-t-foot specimen of this species, recently taken was estimated to weigh approximately 501) pounds and possessed a caudal lobe measuring 71 feet. The long caudal lobe is apparently used to stun prey. the white sharks, are streamlined and Relation to Man possess large stiff pectoral fins for The relation of sharks to man stabilizers. In contrast, most rather sterns from commercial utilization of sluggish sharks, such as the cow sharks, nurse sharks, and even the sharks and shark products by man and bull sharks, are less streamlined and from damage caused man by sharks. often more bulky, or display adapta­ Until 1950, a commercial fishery tions to other ways of life . The large for sharks was carried on in the United whale sharks, which engulf and strain States, on both coasts, and the annual their prey in great volumes of water, catch reached a maximum of 4.5 mil­ have terminally placed mouths to better lion pounds landed on the Atlantic coast facil~tate their feeding. The basking and 39 million pounds on the Pacific sharks have extremely wide mouths coast. The fishery was carried out nearly terminal in position to better chiefly to obtain the shark-liver oil engulf and strain great quantities of which is rich in vitamin A. Byproducts water. Most other sharks have their of the oil industry included: hides, mouths placed far ventrally. used for high-quality leather products; fins (of some species), sold as spe­ Several deep- species, includ­ cialty food items; meat, salted or sold ing probably the little green dog shark fresh as food for human consumption in that lives at depths exceeding 1,000 some areas; carcasses, ground into feet, possess the ability to produce meal; and teeth and vertebrae. cleaned light in their otherwise totally dark and sold to curio shops. With the advent environment. of cheaper sources of vitamin A. shortly

9 prior to 1950, IllOst of the commercial shark fishing operations in this coun­ try were suspended. Sharks interfere with operations in many instance s. In the Gulf of Mexico, sharks occa­ sionally cause severe economic los ses through their habit of biting and tearing the trawl nets to get at the catch. An estimated 20 percent loss in salable fish due to shark damage has been cited for the tuna long line fisheries of the world. Also, in many localities, the seasonal abundance and the local concentration of some species of sharks force cessation of gill-net operations and otherwise influence the choice of gear and the 1 0 cat ion of fishing grounds. In 1958 the American Instltute of Biological Sciences (AlBS) inaugurated a Shark Research Panel for the pur­ pose of studying all aspects of the of elasmobranch fishes. One of the functions is to compile a shark­ attack £lIe. Records a c cum u 1 ate d through this effort show that, in 1959, there were 39 shark attacks on man Removing the liver from a large silky shark. involving at least 18 fatalities.

SKATES AND RAYS Numbers and General Distribution taceans that characterize the tidal zone. Below 1,500 fathoms, our knowl­ Included in the same group with the edge of the bottom fauna is scanty, but, skates and rays are the , if skates and rays are present, they , electric rays, stingrays, undoubtedly are very scarce. eagle rays, and mantas. All told, prob­ ably about 400 species of the group are The eagle rays, mantas, and a few known. others are capable of tremendous leaps from the water, and authentic reports The group as a whole is widely are available of these large fishes distributed. Like the sharks, more towing moderate- size ve ssels for rela­ species, and probably more individuals, tively great distances at high speeds. are found in tropic and subtropic seas Other skates and rays probably rely on than in colder waters; but there are short bursts of speed followed by several species that do frequent the periods of drifting or lying quietly on cold-water regions of the world, in­ the bottom rather than on sustained cluding some skates that live in water high speed or swimming power. Even as cold as 290 F. Skates, rays, and the mantas, usually seen only on the their close relatives may be found from surface of the water, probably spend the shoreline to a depth of about. 1,500 some of their time resting quietly on fathoms. At least one species occa­ the bottom. Stingrays (Dasyatis) are sionally splashes along the very edge bottom dweller s and are sometimes of the sea, on the tide line of the found partly buried in the sand with beaches, in search of the small crus- only the eyes and the area surrou~ding

10 DORSAL VENTRAL

N ostr i l

,-. r""-)

,-. ~ ,...... ,

Pectoral Fin ~------r ,,/ Gill slits ';, I , , I

I~ Cloaca

/"'::I___ Caudal Fin

2 nd

Dorsal Fin

A generalized skate illustrating terms used in description. the s visible. But there are Abundance e x c eptions--one species, at least, In numbers of individuals, the i s p e l a g i c. The , skates and rays compare more favor­ Dasyatis violacea, has been taken by ably with the sharks than with the bony Bureau research vessels in both the fishes. They are abundant locally and Atlant ic and Pacific near the surface seasonally, but cannot be considered hundreds of mile s from land. abundant inhabitants of the seas in general. Stingrays are often sufficiently Although basically marine fishes, numerous along the coasts of South and a few speci es of stingrays have taken , in the Caribbean, and up r esiden ce in the lower parts on the coastal grounds of the of some rivers in Florida and South southern portion of the United States to America, and sawfish e s f r e que n t 1 y constitute a serious nuisance to com­ enter fresh water--often f o r prolonged mercial fishing operations. They are periods. also found around some bathing beaches,

11 where they take a yearly toll in injured fish. On rare occasions the devil rays bathers. Some skates are found off the appear to scoop up their prey with the coasts of the northern European coun­ help of the cephalic extensions of their tries in sufficient abundance to support pectoral fins, and folk legend, ap­ small but continuous foodfish fisheries. parently based on fact, states that they will even wrap their w ing s around The larger skate s and rays are ap­ anchor cables. parently less numerous, but our knowl­ edge of their abundance is based, for The electric rays and torpedoes the most part, on incidental sightings possess the structural orgamzation and of these creatures from coastwise the ability to transmit an electrical vessels. Claims of great local abun­ shock. The mechanism by which thIS i s dance of eagle rays, mantas, and simI­ achieved is not completely known. It lar fish are often based more on the appears to involve an increase In great amount of publicity given a few activity of the nerve - muscle complex, sighting s than on actual numbe r s. common to all animals. Release of a demonstrable e lectric discharge i s a Size heIghtened example of a prevalent phe­ nomenon. A nervous response involves The mantas, reputed to reach a an electrical Impulse traveling along a breadth of 22 feet and a weight of over pair of nerve fibers and acting upon 3,000 pounds, are the largest fish of the a section of the brain (at one end of the group. Sawfishes are also quite large circuit) and a muscle (at the other end). and may reach a total length of 22 feet, The "electric organ" of torpedoes is a although actual verified records do not wing - shaped mas s of modified muscle exist for specimens this large (see tissue, richly innervated, lying m the table on the inside cover). At the other forepart of the body on either side of end of the range there are a few species the . A so-called of ray and torpedoes that never exceed "electric lobe" in the brain completes a few inches In breadth. the nerve pathway. Textbooks of com­ parative or general physiology may be Food and Feeding Habits consulted for further particular s . Most skates, rays, and closely re­ lated forms are bottom feeders, and The AtlantIC , a relatively , , other crustaceans, large ray which reaches a l ength of clams, and worms constitute their nearly 6 feet and may occasionally principal food items. Many skate s cap­ weigh as much as 100 pounds, is saId ture prey by swimming quickly above to have produced a discharge amountmg the victim, dropping down on it, and to 220 volts. This is probably very preventing its escape by covering it nearly the maximum dIscharge to be with their winglike fins. Some of the expected from a ray and IS much less more sluggish rays appear to lie in than the maximum reported for electrIC wait for their prey--half covered with . Very Ettle i s known about the sand, and many of the member s of the discharges of other e l ectric rays and group seem to prefer to feed only at torpedoes, except that the discharges night. of the are pulsed and de­ livered in rapid succession- -very simi­ Sawfish feed primarily on and in the lar, in prInciple, to the mechanism used bottom, which they scrape and dig up in present-day applications of elec­ with their saws, but they also feed in tricity in commercial fishing. Exami­ open water, where they capture their nation of stomach contents of a number prey by slashing their saws around in of electric rays and torpedoes suggests the midst of schools of fish. that the discharges are used in food getting, for the size of many of the A few rays--princip'ally the devil fishes found in stomachs is larger than rays and mantas--feed on pelagic would be expected on the basis of more , mysids, and small school ordinary means of capture.

12 Anatomical Features the wound resultln from a r y- pin puncture is apparently at rtbutabl 0 Perhaps the most outstanding ana­ secretion of poison In at 1 t tomical feature of many member s of instances, but IS also du the group is the wide expansion of the cumulated coverln of dIrt, hm, pectoral fins, a feature which gives the bacterIa that clm s to the pIn , to fish a disclike shape. The gill openings configuration of the wound, nd to are entirely on the ventral surface, with jagged nature of the cut. Owm to he no portion of them extending above the deep-puncture character of th pIn plane of insertion of the pectoral fins. wound, conditions are optimal for n­ The sharklike rays, including the saw­ grene. fish and the , are classified as true rays on the basis of gill posi­ Examination of the mouths and tion, certain differences in skeletal structure of rays and skat pro­ structure which seem to more nearly vides ready explanation of how om of ally them to rays than to sharks, and a these creatures can feed upon hard­ few other, possibly more obscure, shelled crustaceans and mollusks. Un­ characteristic s . like the teeth of most sharks, which are Several species of rays that inhabit pointed, sharp, and fitted for t armg, shallow water are provided with long, the teeth of the typical rays and skate sharp spines on the base of their tails. are blunt, platelike, or arranged lIke a These spines are capable of inflicting pavement over the Jaws and well- SUIted serious injuries on persons coming in for crushing. Jaw musculature is cor­ contact with them. The seriousness of respondingly powerful.

A "typical" ray. the roughtatl stingray, D03rali3 c""trouro. nus Sj)eClIT1eIl measured 285 pounds. Such rays are taken frequently In tra ..... l dra 1 the east c

13 Relation to Man but with less vitaIllin-A content than sharks. Rays have never been as iIllportant, cOIllIllercially, as sharks; but sIllall Danger froIll stingray wounds has fisheries for rays are in existence in been discussed. Stingrays are found Illany parts of the world. The Illeat of IllOSt often along quiet, Illuddy shores. the wings (pectoral fins) is said to be The spines of stingrays have provided of excellent quality, but little Illarket­ priIllitive peoples wlth weapons, and ing of ray Illeat is done in this country. even today, in SOIlle countrie s, there SOIlle of the larger skates and rays are laws prohibiting or liIlliting the contain appreciable quantities of oil possession of stingray spines.

CHIMAERAS Numbers and General Distribution group IS so little known. Surely, COIll­ pared with the bony flshes, they are Only about 2 dozen species of this infrequently ob served or collected, but group are recognized at the present this Illay be, in part, a function of dif­ tiIlle. This nUIllber will, perhaps, be ference s in dIstribution or reaction to added to as deep-water and Illidwater collecting gear. The chiIllaeras ap­ oceanic inve stigations becoIlle Illore parently occur in a "patchy" distnbu­ cOIllpr.ehensi ve. tion pattern, and when and w her e present, they often are relatively abun­ ChiIllaeras are worldwide in dis­ dant. Much Illore work reIllains to be tribution and are found in alIllost all done before probleIlls of chlIllaera seas--tropic, subtropic, teIllperate, dlstributlon are cOIllpletely resolved. and boreal. In IllOSt instances, how­ In SOIlle parts of the world, the fishes ever, they appear to be liIllited to the are sufficiently abundant to forIll the cooler water Illasses. For that reason, basis for sIllall fishenes. In the north­ in the tropic and subtropic seas, they western Atlantic (along the eastern are generally found in the deeper and coast of the United States), the group therefore cooler depths or in cold is known only froIll isolated speCIIllens upwellings. ChiIllaeras have been found collected with sIllall scientiflc gear. frOIll near the surface to depths of ap­ In the Gulf of Mexico, several speCl­ proxiIllately 1,500 fathoIlls. Veryprob­ Illens have been trawled on or beyond ably they exist in deeper waters also. the edge of the , and Abundance where they were taken at all, they ap­ pear to be found In aggregations. Off It is difficult to assess the abun­ Puerto Rico, in the Caribbean, sIllall dance of the chiIllaeras because the aggregations also appear to be present.

Sensory mucous Canals I~t. Dorsal Fin 2nP Dorsal Fin

Upper Caudal Fin Ivic Fin

r Caudal Fin

A generalized chimaera illustrating terms used in description.

14 On the west coast of the country, back into which the spine and the first there are a few shallow-water repre­ dorsal fin can be folded, and a straight, sentatives of the group which are thin macrouridlike tail (h e n c e the locally abundant. "ratfish" for both the bony-fish group Macrouridae and the Size chimaeras).

In contrast with the wide size Chimaeras breathe by taking in ranges exhibited by sharks, skates, water through their nasal apertures, and rays, the chimaeras constitute a pas sing it over the through respir­ relatively uniform size group, with atory channels (and removing part of extremes placed just below 2 feet at the oxygen from it), and sending it out maturity to a little over 6 feet. through the single openings on either side. Food and Feeding Habits Chimaeras rest on the bottom at The chimaeras are carnivorous irregular intervals. When doing so, and therefore predacious, as are most they are said to use the tips of the member s of the class Chondrichthyes. large pectoral and pelvic fins as Chimaeras, however, are feeble "props" to support themselves off the swimmer s and are selective in their softer substrates. feeding only to the extent that they feed upon animals with limited powers Relation to Man of escape- -principally small fish and . In the Orient, where In the Pacific Northwest of the they are fished with handlines, they United States, there is a minor fishery apparently bite a wide variety of baits. for chimaeroids; the liver oil has a small commercial value. In some other Anatom ical Features parts of the world, however, the fish are used on a large scale, owing to Two out of three families of chi­ their greater availability, high oil con­ maeras are characterized by oddly tent, and edible quality. The fish form shaped prolongations of their snouts, the basis for an industrial oil fishery whereas members of the third family in some Scandinavian countries and a possess gently rounded noses. These foodfish fishery in New Zealand as well rostral characteristics have been re­ as in China and some other parts of sponsible, in large, for the various the Orient. common names applied to the group, including "goat fish", "elephant fish", Chimaeras present little or no "", and others. Chimaeras danger to humans, for despite their are also characterized by their large, ability to bite rather viciously, they weak fins, a large spine in front of the are usually either dead or dying when fir st dor sal fin, a groove along the pulled from the water.

15 ANNOTATED LIST OF REFERENCES

The literature on sharks, s ka t es, rays, GENERAL REFERENCE PAPERS and chimaeras is voluminou s and com­ NATURAL HISTORY pos ed of contributions from all m ajor countries of the world. The list of r ef­ The following papers, although dealing erences following can only provide a p r imarily with particular sharks, or glimpse of the total. The reader may groups of sharks, are selected as gen­ scan the bibliographies of the w or ks eral owing to the large amount of dis­ consulted for further clues as to the cussion of a more general nature that nature and extent of literature. has been included in them: Because is a dynamic subje ct, zoological literature is constanltly in­ creasing in volume, and zoologica l con­ OLSE N, A. M. cepts are constantly undergoing modifi­ 1954. The biology, migration, and cation. Some of the most impor tant growth r ate of the , current references are, therefore, found Galeorhinus australi s (Macleay) in journals rather than in textbooks. (C archarhinidae) in southeastern Austra lian waters. Australian J. Ma r. Fresh wat e r Res. 5(3):353- GENERAL REFERENCE BOOKS 410. RIPLEY, WILLIAM E . 1946. The biology of the soupfin Gale­ The following books should be re­ orhinus zyopterus and biochem­ garded as basic references for the ical s tudies of the liver. The serious student of elasmobranchs: soupfin shar k a nd the fishery. Calif. Div. F i sh Game. Bull. 64: BIGELOW, HENRY B., and WILLIAM C. 6- 37. SCHROEDER. SPRINGER, S TEWAR T. 1948. Sharks. In Fishes of the western 1960. Natural history of the sandbar North Atlantic. Sears Found. Mar. shar k Eulamia milberti. U.S. Fish Res. Mem. 1 (1):59-576. Wildl. Serv., Fish. Bull. 61 (178) : 1953. Sawfishes, guitarfishes, skates, 1- 38. rays, and chimaeroids. Fishes of the western North Atlantic. Sears Discusses the natural history of a common Found. Mar. Res. Mem. 1 (2):xv shark of the coastal waters of the east coast of 588. the United States, with many comments applicable to elasmobranchs in general. These two companion volumes, although largely systematic in scope, summarize most STRAS BURG, DONALD W. of the information available at the time of 1958 . D i s t rib uti 0 n, abudance, and printing on habits, food, Size, abundance, repro­ ha bits of pelagic sharks in the duction, and distribution of the known chon­ c entral Pacific Ocean. U.S. Fish drichthoid fishes in the western North Atlantic. Wildl. Servo Fish. Bull., 58(138: 335- 361. McCORMICK, HAROLD W., TOM ALLEN, and CAPTAIN WILLIAM Discusses the natural history of 12 species of YOUNG. oceanic sharks on the basiS of observations 1963. Shadows in the sea. Chilton made in the course of longline tuna fishing Books, Phila.:xii + 415 p. cruises. 'The only paper of its sort dealing with NORMAN, J. R., and F. C. FRASER. shark populations of offshore waters. 1938. Giant fishes, whales and dol- phins. Putnam, Lond on:xxii + TEMPLEMAN, WILFRED. 376 p. 1944. The life-history of the spiny dogfish (Squalus acanthias) and A general and popularized account of the size, the vitamin A values of dogfish habits, and occurrence of the common large liver oil. Newfoundland Dep. Nat. marine animals. Resourc. Res. Bull. 15:1-102.

16 GUIDES TO THE CLASSIFICATION AND FOWLER, HENRY W. NAMING OF CHONDRICHTHOID FISHES 1941. The fishes of the groups Elas­ mob ran chi i, H 0 1 0 c e ph a Ii, AMERICAN FISHERIES SOCIE TY • Isospondyli and Ostarphysi ob­ 1960. A list of common and scientific tained by the U.S. Bureau of Fish­ names of fishes from the United eries steamer "Albatross" in 1907 States and Canada. 2d ed. Amer. to 1910, chiefly in the Phillippine Fish. Soc., Spec. Publ. 2:102. Islands and adjacent seas. U.S. Nat. Mus. Bull. 100, 13:x 879 p. Lists the common and sCientific names of the HI LDE B RA ND, SAM UE L F., and most common jawless, chondrichthoid, and tele­ WILLIAM C. SCHROEDER. ostean fishes and indicates the general area of 1928. Fishes of . Bull. distribution of each. U.S. Bur. Fish. 43(1):1-366. JORDAN, DAVID STARR, andHENRYW. REGION KEYS AND GUIDES TO FOWLER. IDENTIFICATION 1903. A review of the elasmobranch­ iate fishes of Japan. Proc. U.S. The following papers provide lists, Nat. Mus., 26(1324):593:674. keys, discussion, or guides to the iden­ KATO, SUSUMU. tification of chondrichthoid fishes in the 1964. Sharks of the Carchar­ areas indicated in th titles. In most hinus associated with the tuna cases, the papers have an even wider fishery of the eastern tropical range of applicability (in a geographical Pacific Ocean. U.S. Fish Wild!. sense), as many elasmobranchs are Ser., B., Circ. 172:ii 22 p. far- ranging animals. Because the sub­ RADCLIFFE, LEWIS. ject matter of these papers is described 1916. The sharks and rays of Beau­ so aptly in the titles, no further annota­ fort, . Bull. U.S. tion is given in this section. Bur. Fish., 34(882):241-284. ROEDEL, PHIL M., and WILLIAM E. B AUG H MAN, J. L., and S T E WAR T RIPLEY. SPRINGER. 1950. sharks and rays. 1950. Biological and economic notes Calif. Fish Game, Fish. Bull. on the sharks of the Gulf of 75:1-88. Mexico, with especial reference R OS E NB L A T T, RICHARD H., and to those of Texas, and with a key WAYNE J. BAL DWIN. for their identification. Amer. 1958. A review of the eas tern Pacific Midland Natur. 44( 1 ):96-152. sharks of the genus Carcharhinus, BEEBE, WILLIAM, and JOHN TEE- VAN. with a redescription of C. mal­ 1941. Eastern Pacific Expeditions of pa10ensis (Fowler) and California of the Zoological records of C. remotus (Dumeril). Society. XXV. Fishes from the Calif. Fish Game 44(2):137-159. tropical eastern Pacific. (From SCHULTZ, LE 0 NA R D P., EARL S. Cedros Island, Lower California, HERALD, ER NES T A. LACHNER, south to the Galapagos Islands ARTHUR D. WELANDER, and LORENP. and northern Peru). 2, Sharks, WOODS. Zool. 26(74):viii + 577. 1953. Fishes of the Marshall and CASEY, JOHN G. Marianas Islands. U.S. Nat. Mus. 1964. Anglers' guide to sharks of the Bull. 2 02 1: 1 - 685 • northeastern United States, Maine SMITH, J .L.B. ! to Chesapeake Bay. U.S. Fish and 1950. The sea fishes of southern Wildl. Serv., Bureau of Sport Africa. Central News Agency, Fisheries and Wildlife, Circular , vxii 564 p. 179,32p. TOR TONESE, ENRICO. CLEMENS, W. A., and G. V. WILBY. 1956. Fauna d'Italia. Vol. 2, Lepto­ 1946. Fishes of the Pacific coast of cardia, Ciclostomata, Selachii. Canada. Fish. Res. Bd. Can., Bull. Edizioni Cal de r i n i, Bologna, 68:368 p. 2: 1-332.

17 WHITLEY, G. P. NICOL. J. A. COLIN. 1940. The fishes of Australia. Part 1, 1960. The biology of marine animals. The sharks, rays, devilfish, and Sir Isaac Pitman and Sons, Ltd., other primitive fishes of Australia London, xii + 707 p. and New Zealand. Royal Zool. Soc. New South Wales, Sydney, A general reference on ecological physiology 1: 1-280. of marine animals including members of the class Chondrichthyes. ANATOMICAL REFERENCES PROSSER, C. LADD (Editor). DANIEL, J. FRANK. 1950. Comparative animal phys­ 1934. The elasmobranch fishes. Univ. iology. W. B. Saunders Co., Phil­ Cali£. Press, Berkeley, 332 p. adelphia, x + 888 p.

Devoted exclusively to a discussion of the A comprehensive text covering the animal anatomy of sharks, skates, and rays. kingdom, specific sections on nutrition, foods and feeding, excretion, metabolism, Circulation, HYMAN, LIBBIE H. chemoreception, photoreception, muscle and 1942. Comparative vertebrate anat­ electriC organs, bioluminescence, nervous sys­ omy. 2d edition. University of tem and other subjects. Chicago Press, Chicago, 544 p. NORMAN, J. R. REFERENCES ON THE RELATION OF 1949. A history of fishes. A.A. Wyn, SHARKS TO MAN Inc., New York, 463 p. ALVERSON, DA YTON L., and MAURICE A generalized account of the anatomy and E. STANSBY. lives of the fishes. 1963. The spiny dogfish (Squalus acanthias 1 in the northeastern Pa­ ROMER,ALFREDSHERWOOD. cific. U.S. Fish and Wildl. Serv., 1949. The vertebrate body. W. B. Spec. Sci. Rep. 447, 25 p. Saunders Co., Philadelphia, viii COPPLESTON, V. M. 643 p. 1958. ! Angus and Robertson, Sydney, 266 p. A standard textbook of comparative vertebrate anatomy. Contains a discussion of the anatomy A general a~count of damage wrought by sharks of the dog-shark. and of their attaCks on man. PHYSIOLOGICAL REFERENCES GILBER T, PERR Y W., EDITOR. HEILBR UUN, L. V. 1963. Sharks and survival. D.C. Heath 1952. An outline of general physiology. and Co., Boston. xiv 578 p. 3d ed. W. B. Saunders Co., Phil­ GILBER T, P. W., L. P. SCHULTZ, and adelphia, xiv + 818 p. STEWAR T SPRINGER. 1960. Shark attacks during 1959. Sci. A technical treatise dealing largely with phys­ 132 (3423):323-326. iology at the cellular level. Chapter 29, "The LLANO, GEORGE A. Production of " and Chapter 30 1957. Sharks v. men. Sci. Amer. 196 "Bioluminescence" are recommended. (6) :54- 61.

MS #1481

18 TABLE 2.--~imum length and widths of common species of sawfishes, guitarfishes, skates, rays and chimaeras

Species Mlximum length Mlximum width Common name Scientific name

Smalltooth sawfish ••••• Pristis pectinatus ...... 18 feet --- Largetooth sawfish ••••• Pristis perotteti ...... •.. 22 feet --- Atlantic guitarfish •••• lentiginosus .... J feet --- •• Rhinobatos productus ...... 4 feet --- •••• brasiliensis ...•..• 1 foot 6 inches --- ••••••• Torpedo nobiliana . .•..•.... 5 feet 11 inches --- •••••••••••••• binoculata .•.•...... 6 to 8 feet 6 feet ••••••••• Raja laevis ....•....•..••.. --- 5 feet ••••••••••• Raja erinacea •...... •.••.. 1 foot 9 inches 1 foot ••••• Dasyatis centroura •...... • --- 7 feet Diamond stingray ••••••• Dasyatis dipterurus ..•.•... 6 feet --- •••••• Dasyatis sabina •.•.•.••.. .. 2 feet 9 inches 1 foot 4 inches

Gulf dwarfskate •••••••• sinus-mexicanus. 1 foot 2 inches 0 feet 7 inches

Spiny •••• Gymnura altavela .•••••.•.. 4 feet 8 inches 6 feet 10 inches ••• Gymnura micrura •••.•••..• --- J feet 6 inches Spotted •••••• Aetobatis narinari ••..•.•.. --- 7 feet 7 inches Bat stingray ••••••••••• Myliobatis californicus ••.. --- 4 feet Atlantic manta ••••••••• Manta biros tris ...... 17 feet 22 feet Cl1i.ma.era. • . . ,. ,. ,. ,. ,. . ,. ,. ,. ,. ,. affinus •• •.••••. 4 feet 1 inch --- Ratfish •••••••••••••••• Hydrolagus colliei ••.•••••• J feet 2 inches ---