SHARKS

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click for previous page 410 Sharks DALATIIDAE Kitefin sharks Diagnostic characters: Dwarf to moderately large sharks, with cylindrical or slightly compressed bodies, with lateral ridges absent between pectoral and pelvic fins and without precaudal pits, caudal keels present or absent. Head with 5 gill slits, all anterior to pectoral fins, the fifth not abruptly longer than the others; spiracles always present, large and just behind eyes; eyes on sides of head, without nictitating eyelids. Snout short to moderately elongated, narrow, conical, not flattened and not formed as a rostral saw;no barbels on snout; nostrils fairly wide-spaced, internarial width greater than or subequal to nostril width; mouth short and nearly transverse, lips smooth or papillose; teeth strong-cusped, dissimilar in both jaws, upper teeth narrow, and needle-like, without cusplets; lower teeth compressed, broad, blade-like, and without cusplets, adjacent teeth imbricated, upper teeth much smaller than lowers. Two dorsal fins either without spines on their anterior margins or with a small grooved spine present on first dorsal fin; dorsal fins small, rounded, narrow, and with weakly concave posterior margins; first dorsal fin subequal in area to second or smaller; origin of first dorsal fin close to or well in front of pelvic-fin origins, behind pectoral-fin insertions and opposite or (usually) behind pectoral-fin free rear tips; no anal fin; caudal fin strongly asymmetrical to nearly symmetrical, with subterminal notch present and with a lower lobe varying from virtually absent to very strong; pelvic fins variably smaller to larger than second dorsal fin. Dermal denticles close-set, not greatly enlarged and plate-like. Colour: body greyish to blackish brown, fins either colour of body or with transparent webs, body without conspicuous black marks, luminescent organs present or absent. no nictitating eyelid teeth Dalatias licha dorsal fin with or without spines or with small grooved spine on 1 st dorsal fin Habitat, biology, and fisheries: Occurs in deep water near the bottom on continental and insular slopes between 200 to at least 1 800 m, but most species are dwarf oceanic sharks and occur in the epipelagic, mesopelagic, and probably bathypelagic zones. Occasional individuals occur in shallow water on the continental shelves, and may wash up on beaches. Circumglobal in temperate to tropical seas and may range into higher latitudes. Feed on a wide variety of bony fishes, other elasmobranchs, cephalopods, crustaceans, worms, and tunicates; some species are partially ectoparasitic and take chunks out of larger marine animals, including bony fishes, elasmobranchs, and cetaceans. Reproduction is ovoviviparous, with 6 to 16 young per litter. In the Far East and the eastern Atlantic one kitefin shark, Dalatias licha, is commonly fished with line gear and bottom trawls, and fixed bottom nets for human consumption and for their livers, which are extremely large, oily, and have a high squalene content. 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 slits abruptly longer than others;mouth broadly rounded;teeth not imbricated, upper teeth nearly as large as lower teeth, with cusplets present in large juveniles and adults. 5 th gill slit abruptly larger than others no anal fin body with large plate-like denticles Echinorhinidae
Squaliformes: Dalatiidae 411 Squalidae: snout flattened; nostrils far apart; upper teeth nearly as large as lowers, both upper and lower teeth imbricated and blade-like; precaudal keels and usually upper precaudal pits present; fin spines present on both dorsal fins, second dorsal fin falcate; no subterminal notches on caudal fin. Centrophoridae: snout flattened; nostrils far apart; both upper and lower teeth compressed, imbricated and blade-like; dorsal fins larger and with origin of first anterior to pectoral-fin rear tips; strong fin spines present on both dorsal fins. dorsal-fin spines present Squalidae Centrophoridae Etmopteridae: snout flattened; nostrils far apart; cusplets present on upper teeth; fin spines present on both dorsal fins; origin of first dorsal fin over or behind the pectoral-fin free rear tips; second dorsal fin more or less falcate; body usually with conspicuous black markings and luminescent organs. Somniosidae: snout broader and more flattened; nostrils far apart; species in the area with fin spines on both dorsal fins. dorsal-fin spines present Etmopteridae precaudal keel and pits usually present Oxynotidae: body high and compressed; conspicuous lateral keels present on abdomen; dorsal fins very high and angular, large dorsal-fin spines present 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 dorsal surface of head; anterior margins of pectoral fins extending forward past gill openings and partly concealing them; pelvic fins also very broad, wing-like. All other shark families: anal fin present. snout elongated and flattened barbels eyes on dorsal surface of head strong spines on both dorsal fins dorsal-fin spines present Somniosidae Squatinidae Pristiophoridae trunk flattened dorsoventrally
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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 and 46: Squaliformes: Etmopteridae 401 Etmo
Page 47 and 48: Squaliformes: Somniosidae 403 Squal
Page 49 and 50: Squaliformes: Somniosidae 405 List
Page 51 and 52: Squaliformes: Somniosidae 407 Zameu
Page 53: Squaliformes: Oxynotidae 409 Echino
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
Page 101 and 102: Carcharhinidormes: Proscylliidae 45
Page 103 and 104: 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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