Cookiecutter shark is a small shark known for the unusual wounds it causes as it feeds. The shark attacks and feeds on other sharks, large fish, and marine mammals. The cookiecutter shark has a hinged mouth that can open wide. It has small upper teeth and large, interconnected lower teeth. When feeding, the shark attaches itself to the body of prey with its large lips and teeth and slices off a small, circular plug of flesh, leaving a distinctive wound. The wound resembles the marks made by a cookie cutter on dough.
Cookiecutter sharks are found in tropical and temperate waters of the Atlantic, Indian, and Pacific oceans. They inhabit deep water during the day and have been found more than 3,300 feet (1,000 meters) below the surface. At night, cookiecutter sharks rise into shallow water in a diel (daily) vertical migration, most likely to feed.
Cookiecutter sharks are brownish-gray and measure only about 12 to 18 inches (30 to 45 centimeters) long. They have a cigar-shaped body, a blunt nose, and large eyes. Like many other deepwater sharks, cookiecutter sharks can produce their own light from specialized organs called photophores. These organs cover the ventral (bottom) surface of the body. The light helps them blend in with the water when viewed by predators from below. Cookiecutter sharks also have a band of dark color around their neck. Scientists believe this marking gives the sharks the appearance of a smaller fish. This may attract larger predators that the cookiecutter shark can then attack. Cookiecutter sharks also eat squid as well as small deepwater fish.
Cookiecutter sharks are ovoviviparous. That is, the female protects the eggs within her body until they hatch. The young of ovoviviparous sharks are born alive. A cookiecutter shark litter may contain 5 to 10 pups.
Humans do not often encounter cookiecutter sharks. However, reports of people with circular wounds after being bitten while swimming have been recorded. Underwater electrical cables, machinery, and even ships and submarines have been found bearing the distinctive bite marks of cookiecutter sharks.
