The Cookiecutter shark (Isistius brasiliensis) is
a small, deep-water shark named for the cookie-shaped wounds
it leaves on larger fish and marine mammals. It is also known
as Cookie-cutter shark or the Cigar shark, due to the cigar-like
shape of its body.
The Cookiecutter has a cylindrical body that reaches up to
20 inches (50 cm) in length. It has a conical snout, and 2
low spineless dorsal fins positioned at the posterior end
of the body. It is dark brown to black on its dorsal side,
lighter ventrally, and possesses a dark collar around the
gill region. The entire ventral surface, with the exception
of its dark collar, is covered in a dense network of tiny
photophores which emit a greenish glow (bioluminescent). This
glow is reported to last as long as three hours after this
The cookie-cutter shark has unusual feeding habits that enable
it to prey on animals much larger than itself. It attaches
its strong, sucking mouth to its prey and then twists, slicing
out a plug of flesh. After detaching, it swims away to digest
its meal. It preys on an assortment of deepwater organisms,
including crustaceans, squid, large bony fishes, whales, and
even large sharks. Cookie-cutter sharks have been known to
bite into submarines, which they apparently mistake for prey.
Living in the dark depths of the ocean, the cookie cutter
shark can be found to depths of 11,500 feet (3,570 m). At
night, the cookie cutter ventures to the surface to feed,
but spends its days in the depths.
Cookie cutter sharks live in the depths of all the oceans
near the equator where the water is warm.