NOVA Online | Island of the Sharks

Order

Family

Species

Squaliformes
Dogfish Sharks
This order of three families and more than 80 species features sharks with cylindrical bodies bearing two dorsal fins (some with spines), no anal fin, and long snouts. Both jaws in many species have strong cutting teeth in short mouths. Dogfish sharks live in all oceans, reaching depths of almost 20,000 feet. All species hatch young from eggs within the body.

ECHINORHINIDAE
Bramble Sharks
Appearance: Large sharks with stocky, cylindrical bodies and widely arched mouths. Their first dorsal fin lies over the pelvic fins.

Echinorhinus brucus
Bramble shark

Size: The bramble shark reaches a length of over 10 ft, and the prickly shark grows to about 13.2 ft.

Habitat: Both species mainly dwell in deepwater slopes. They range down to almost 3,000 ft but occur on the shelves in water as shallow as 36 ft.

Distribution: The bramble shark ranges widely in temperate and tropical seas. Currently, the prickly shark is known only as a Pacific Ocean dweller.

Diet: Bony fishes, other smaller sharks, octopuses, squid, crabs and eggcases of sharks and chimaeras.

Shark bite: Prickly sharks have been observed suspending themselves almost motionlessly just off the sea bottom. The reason for this hovering behavior is unknown.

Two Species

SQUALIDAE
Dogfish Sharks
Appearance: A diverse group which ranges from very small to gigantic. They have stout to slender bodies, variably sized spiracles, and mouths ranging from broadly arched to transverse. The first dorsal fin is in front of the pelvic fins.

Squalus mitsukurii
Shortspine spurdog

Size: Some dogfish sharks reach six to eight inches and are among the smallest of living sharks; many reach between 12 and 36 in; the giants of the family, the Greenland and Pacific sleeper sharks, many reach 23 ft in length.

Habitat: Most dogfish sharks are found on or near the bottom on temperate to tropical continental and insular slopes. Some occur on the continental shelves; a small number of species are oceanic.

Distribution: Probably a greater range than any other shark family. Different species are found in all seas from the Arctic to the sub-Antarctic.

Diet: Bony fishes, other sharks, cephalopods, crustacea, and other invertebrates. Larger members of the family also eat marine mammals.

Shark bite: The piked dogfish shark weighs in water only 2.7 percent of what it weighs in air.

70 Species

OXYNOTIDAE
Roughsharks
Appearance: Small, strange-looking sharks with highly compressed bodies, rough skin, small to large spiracles, transverse mouths with lip papillae, strong dorsal fin spines, and a first dorsal well in front of the pelvic fins.

Oxynotus bruniensis
Prickly dogfish

Size: Most grow to less than 3.3 ft, though one species sometimes reaches almost 5 ft.

Habitat: Upper continental and insular slopes and outer shelves at depths of between 13 and 2,375 ft.

Distribution: Temperate and tropical seas.

Diet: Bottom invertebrates and small fishes.

Shark bite: Roughsharks rely on their expanded body cavities and large oily livers to attain neutral buoyancy, so they can hover and swim without needing forward motion for lift.

Five Species