SHARKS

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402 Sharks SOMNIOSIDAE Sleeper sharks Diagnostic characters: Small to gigantic sharks, with cylindrical or slightly compressed bodies, with ridges between pectoral and pelvic fins and without precaudal pits and caudal keels. Head with 5 gill slits, all anterior to pectoral fins, the fifth not abruptly longer than the others; eyes on sides of head, without nictitating eyelids.Snout short to moderately elongated, broad, flattened, not formed as a rostral saw; no barbels on snout; nostrils wide-spaced, internarial width greater than nostril width; mouth short and nearly transverse, lips smooth; teeth dissimilar in both jaws, upper teeth narrow, needle-shaped, not imbricated, and without cusplets; lower teeth strong-cusped, blade-like, imbricated, and without cusplets. Spiracles always present, large and just behind eyes. Two dorsal fins with or without spines on their anterior margins, when present spines grooved, usually small, and on both dorsal fins; dorsal fins large, angular, broad, and with convex to weakly concave posterior margins; first dorsal fin variably slightly larger, subequal to, or slightly smaller in area to second; origin of first dorsal fin far in front of pelvic-fin origins, anterior, over, or slightly posterior to pectoral-fin free rear tips; no anal fin; caudal fin strongly asymmetrical, with subterminal notch present and with a lower lobe varying from virtually absent to strong; pelvic fins subequal to or larger than second dorsal. Dermal denticles close-set, not greatly enlarged and plate-like. Colour: body and fins greyish to blackish brown, without conspicuous black marks and luminescent organs. spiracles large, just behind eye no anal fin Habitat, biology, and fisheries: Sleeper sharks mostly occur near the bottom on the continental and insular slopes between 200 to at least 3 675 m;some species are apparently oceanic.In high latitudes members of the genus Somniosus occur on the continental shelves to the intertidal.Circumglobal in most seas, and range from the tropics to high latitudes up to the Arctic and Antarctic oceans. Feed on bony fishes, other chondrichthyans, cephalopods and other molluscs, crustaceans, seals, whale meat, carrion, sea birds, echinoderms, and jellyfish; at least one species takes chunks of meat out of living marine mammals and bony fishes. Reproduction is ovoviviparous, with 4 to 59 young per litter.In the Far East and the eastern Atlantic these sharks are fished with line gear and bottom trawls for human consumption and for their livers, which are extremely large, oily, and have a high squalene content. Remarks: The arrangement of genera and species adopted here follows the forthcoming revision of the FAO shark catalog (Compagno, 1984) by the present author. There may be an additional, undescribed species of Scymnodon or possibly Zameus in the area (S. Springer, pers. comm.), from the Gulf of Mexico. Similar families occurring in the area Echinorhinidae: body set with sparse, large, plate-like denticles; spiracles small and well behind eyes; fifth pair of gill body with large, plate-like denticles slits abruptly longer than others;mouth broadly rounded;teeth not imbricated, upper teeth nearly as large as lowers, with cusplets present in large juveniles and adults; first dorsal-fin origin over or posterior to pelvic-fin origins; pelvic fins much larger than second dorsal fin. 5 Echinorhinidae th gill slit abruptly larger than others
Squaliformes: Somniosidae 403 Squalidae: upper teeth nearly as large as lowers; precaudal keels and usually precaudal pits present; dorsal-fin spines very strong and without grooves, second dorsal fin falcate;no subterminal notches on caudal fin. Etmopteridae:cusplets present on upper teeth;second dorsal fin larger than first and more or less falcate;usually with conspicuous black markings and luminescent organs; species smaller, adults usually do not reach 70 cm. Centrophoridae: upper teeth broader and imbricated; no lateral keels on abdomen; origin of first dorsal fin in front of pectoral-fin free rear tips; dorsal-fin spines strong. Dalatiidae: head narrower, conical; nostrils close together; dorsal-fin spines absent or present on first dorsal fin only (Squaliolus). dorsal-fin spines present Squalidae strong spines on both dorsal fins present Centrophoridae precaudal keel and pits usually present Oxynotidae: lips fringed; body high and compressed; dorsal fins very high and angular, dorsal-fin spines large but buried in the dorsal fins with only the tips exposed. Pristiophoridae: snout elongated into a flattened blade with lateral teeth; barbels present in front of nostrils. dorsal fins high and angular Oxynotidae Squatinidae:trunk much flattened dorsoventrally eyes on upper side of head; anterior margins of pectoral fins extending forward past gill openings and partly concealing them; pelvic fins also very broad, wing-like. snout elongated and flattened barbels eyes on dorsal surface of head dorsal-fin spines present Etmopteridae dorsal fins either without spines or with small grooved spine on 1 st dorsal fin Dalatiidae Pristiophoridae Squatinidae trunk flattened dorsoventrally
Page 1 and 2: click for previous page SHARKS by L
Page 3 and 4: Technical Terms and Measurements 35
Page 5 and 6: General Remarks 361 few museum spec
Page 7 and 8: Key to Families 363 KEY TO FAMILIES
Page 9 and 10: Key to Families 365 12a. Head with
Page 11 and 12: Key to Families 367 22a. Origin of
Page 13 and 14: List of Families and Species 369 DA
Page 15 and 16: List of Families and Species 371 SP
Page 17 and 18: Hexanchiformes: Chlamydoselachidae
Page 19 and 20: Hexanchiformes: Hexanchidae 375 Key
Page 21 and 22: Squaliformes: Echinorhinidae 377 A
Page 23 and 24: Squaliformes: Squalidae 379 SQUALID
Page 25 and 26: Squaliformes: Squalidae 381 3a. Dis
Page 27 and 28: Squaliformes: Squalidae 383 Squalus
Page 29 and 30: Squaliformes: Squalidae 385 Squalus
Page 31 and 32: Squaliformes: Centrophoridae 387 Sq
Page 33 and 34: Squaliformes: Centrophoridae 389 4a
Page 35 and 36: Squaliformes: Centrophoridae 391 Ce
Page 37 and 38: click for previous page Squaliforme
Page 39 and 40: Squaliformes: Etmopteridae 395 Key
Page 41 and 42: Squaliformes: Etmopteridae 397 List
Page 43 and 44: Squaliformes: Etmopteridae 399 Etmo
Page 45: Squaliformes: Etmopteridae 401 Etmo
Page 49 and 50: Squaliformes: Somniosidae 405 List
Page 51 and 52: Squaliformes: Somniosidae 407 Zameu
Page 53 and 54: Squaliformes: Oxynotidae 409 Echino
Page 55 and 56: Squaliformes: Dalatiidae 411 Squali
Page 57 and 58: Squaliformes: Dalatiidae 413 Dalati
Page 59 and 60: Squatiniformes: Squatinidae 415 Ord
Page 61 and 62: Pristiophoriformes: Pristiophoridae
Page 63 and 64: click for previous page Lamniformes
Page 65 and 66: Lamniformes: Odontaspididae 421 2a.
Page 67 and 68: Lamniformes: Odontaspididae 423 Odo
Page 69 and 70: Lamniformes: Mitsukurinidae 425 A s
Page 71 and 72: Lamniformes: Alopiidae 427 ALOPIIDA
Page 73 and 74: Lamniformes: Alopiidae 429 Alopias
Page 75 and 76: Lamniformes: Cetorhinidae 431 A sin
Page 77 and 78: Lamniformes: Lamnidae 433 LAMNIDAE
Page 79 and 80: Lamniformes: Lamnidae 435 List of s
Page 81 and 82: Lamniformes: Lamnidae 437 Isurus ox
Page 83 and 84: Lamniformes: Lamnidae 439 Lamna nas
Page 85 and 86: Orectolobiformes: Ginglymostomatida
Page 87 and 88: Orectolobiformes: Rhincodontidae 44
Page 89 and 90: Carcharhiniformes: Scyliorhinidae 4
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Carcharhiniformes: Scyliorhinidae 4
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Carcharhiniformes: Scyliorhinidae 4
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Carcharhinidormes: Proscylliidae 45
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Carcharhiniformes: Triakidae 459 Si
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Carcharhiniformes: Triakidae 461 Mu
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Carcharhiniformes: Carcharhinidae 4
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click for previous page Carcharhini
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click for previous page Carcharhini
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Carcharhiniformes: Sphyrnidae 499 4
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Carcharhiniformes: Sphyrnidae 501 S
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SHARKS

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