The Portuguese and recently discovered megamouth sharks live in the deepest parts of the ocean. Despite the shark's reputation for viciousness, only a few species of sharks are known to attack humans. Some sharks, including the thresher, brown, and lemon sharks, are fished commercially for food. The mako is a highly prized sport fish. Description and Habits Sharks have skeletons composed of cartilage rather than of bone.
Bottom dwellers tend to be stout and heavy bodied.
The hammerhead shark has a flattened head that resembles a double-headed hammer, with an eye on each stalk. Sharks may be reddish brown, bronze, metallic blue, gray, or nearly black and are often patterned with spots, bands, marblings, or protuberances. Cat sharks are colorful and exquisitely patterned. The pointed end of these denticles projects toward the tail. These modified scales may overlap or may be widely spaced.