Sharks

There are eight orders of living sharks.

The Angelshark order includes the angelsharks and sand devils. These sharks are flattened like rays and tend to live on the ocean bottom in water depths to 4,200 ft (1,300 m). They are found in most oceans, except the central Pacific and Indian Oceans and the polar areas. There are thirteen species, most of which are less than 60 in (1.5 m) long.

The Dogfish order includes the dogfish sharks, bramble sharks, and roughsharks. This is a group of 82 species, 73 of which are dogfish sharks. Dogfish sharks generally have a cylindrical body and elongated snout. They are found in all oceans, usually in deep water. Their size ranges from the 10-in (25 cm) pygmy sharks to the 23-ft (7 m) sleeper sharks.

The Sawshark order consists of five species of sawsharks, with a long, flattened, saw-like snout. They are bottom-dwelling in temperate to tropical oceans, to depths of 3,000 ft (900 m). Adults are 3-5 ft (1-1.6 m) long.

The Frilled shark order consists of the frilled, cow, six-gill, and seven-gill sharks. There are five species, which are found in all oceans, mostly on continental shelves from 300-6,150 ft (90-1,875 m). The body length ranges from 77 in (195 cm) for frilled sharks to 16.5 ft (5 m) for a species of six-gill shark.

The Bullhead shark order consists of eight species of bullhead sharks. They have a wide head, short snout, and flattened teeth for crushing hard prey. They are found in warm continental waters of the Indian and Pacific Oceans, to depths of 900 ft (275 m).

The Carpetshark order includes zebra sharks, nurse sharks, and whale sharks. This is a diverse group of 33 species, all found in warm water, mostly in the Indian Ocean and western Pacific. They may forage on the surface or at the bottom, mostly near shore to depths of about 330 ft (100 m). These sharks have two small projections called barbels under their snout, and most have a shortened, rounded nose and slender, elongated tail fins. Most species are 3-8 ft (1-3 m) long, but whale sharks may reach over 40 ft (12 m). Whale sharks are the largest fish in the world.

The Mackerel shark order includes the sand tigers, basking sharks, megamouth sharks, mako sharks, and white sharks. There are sixteen species, which are found in all but polar waters. The megamouth sharks were only discovered in 1982. The species in this order are found near shore or far from land, in shallow water and to depths of 3,900 ft (1,200 m). Most have a powerful, cylindrical body and elongated snout. Their length A sand tiger shark (Odontaspis taurus.). Photograph by Tom McHugh. The National Audubon Society Collection/Photo Researchers, Inc. Reproduced by permission. ranges from 3-19 ft (1-6 m), with basking sharks reaching over 33 ft (10 m).

The Groundshark order includes the catsharks, hammerhead sharks, and requiem sharks. The latter subgroup contains the blue, tiger, and bull sharks. The groundshark group consists of 197 species found in all ocean habitats. It includes most of the species considered dangerous to humans.