SHARKS

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click for previous page 386 Sharks CENTROPHORIDAE Gulper sharks Diagnostic characters: Small to moderately large sharks, with cylindrical or slightly compressed bodies, without 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; spiracles always present, large and just behind eyes; eyes on sides of head, without nictitating eyelids. Snout short to 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 strong-cusped, dissimilar in both jaws, compressed, broad, blade-like, and without cusplets, adjacent teeth imbricated, upper teeth much smaller than lowers. Two dorsal fins with a long strong grooved spine present on their anterior margins;dorsal fins large, angular, broad, and with weakly concave posterior margins;first dorsal fin larger or subequal in area to second dorsal fin; origin of first dorsal fin far in front of pelvic-fin origins, over or just behind pectoral-fin insertions, and always in front of 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 short; pelvic fins subequal to or smaller than second dorsal fin. 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. no nictitating eyelid 5 gill slits, anterior to pectoral fin Habitat, biology, and fisheries: Gulper sharks mostly occur in deep water near the bottom on the continental and insular slopes from 200 to at least 2 400 m, with one photographed from a bathyscaphe on the ocean floor below 4 000 m and another in the open ocean between the surface and 1 250 m depth in water nearly 4 000 m deep. Occasional individuals venture onto the continental shelves up to 50 m, and one was found by a diver in shallow water. These dogfishes are circumglobal in most seas, and range from the tropics to high latitudes up to Iceland in the North Atlantic.Some of the species form immense schools, and are among the most abundant deep-water sharks. Gulper sharks feed mostly on bony fishes and cephalopods, but also small sharks, chimaeras, shrimp, lobsters, and tunicates. Reproduction is ovoviviparous, with 1 to 12 young per litter. In the Far East and the eastern Atlantic these sharks are commonly fished with line gear, demersal and pelagic trawls, and fixed bottom nets for human consumption and for their livers, which are extremely large, oily, and have a high squalene content.This is possibly the most important family of deep-water sharks for fisheries purposes. 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; no dorsal-fin spines; first dorsal-fin origin over or posterior to pelvic-fin origins; pelvic fins much larger than second dorsal fin. 2 dorsal fins with grooved spines upper and lower teeth of Centrophorus acus 5 th gill slit abruptly longer no anal fin sparse, large, plate-like denticles Echinorhinidae subterminal notch
Squaliformes: Centrophoridae 387 Squalidae: upper teeth nearly as large as lower teeth; precaudal keels and usually precaudal pits present; dorsal-fin spines without grooves; second dorsal fin falcate; no subterminal notch on caudal fin. Etmopteridae: cusplets present on non-imbricated upper teeth; origin of first dorsal fin over or behind the pectoral-fin free rear tips, second dorsal fin larger than first dorsal fin and more or less falcate; body usually with conspicuous black markings and luminescent organs; most species smaller, adult at below 70 cm. dorsal-fin spines present precaudal keel and pits usually present Squalidae Etmopteridae Somniosidae:upper teeth narrow and not imbricated;lateral keels present on abdomen;origin of first dorsal fin usually behind pectoral-fin free rear tips; dorsal-fin spines greatly reduced in species in the area, absent in species found elsewhere. Dalatiidae:upper teeth narrow and not imbricated;origin of first dorsal fin behind pectoral-fin free rear tips;dorsal-fin spine either present on first dorsal fin only (Squaliolus) or absent. dorsal-fin spines present Oxynotidae: upper teeth narrow and not imbricated; body high and compressed; conspicuous lateral keels present on abdomen; 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. Oxynotidae eyes on dorsal surface of head 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. All other shark families: anal fin present. spines on both dorsal fins dorsal fin either without spines or with small grooved spine on 1 st dorsal fin Somniosidae Dalatiidae dorsal fins high and angular snout elongated and flattened barbels 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: Squaliformes: Squalidae 385 Squalus
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 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
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Lamniformes: Lamnidae 437 Isurus ox
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Lamniformes: Lamnidae 439 Lamna nas
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Orectolobiformes: Ginglymostomatida
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Orectolobiformes: Rhincodontidae 44
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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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