Description & Behavior
Cookiecutter sharks, Isistius brasiliensis (Quoy and Gaimard, 1824), aka cookie-cutter shark, smalltooth cookiecutter shark or cigar shark, are small, deepwater sharks named for the cookie-shaped wounds they leave on larger fish and marine mammals.
Cookiecutter sharks live in the warm, deep waters of equatorial oceans, primarily in coastal waters near islands. They inhabit deep waters below 1,000 m during the day and migrate into surface waters at night at around 300 m. They have been found in depths up to 3,500 m.
Feeding Behavior (Ecology)
Cookiecutter sharks, appear to blend with the light from above when viewed from below due to the shark’s ventral photophores that disguise the shark’s outline. The primary prey of the cookiecutter shark are squid, small fish (likebristlemouths), and crustaceans.
This shark also feeds on larger pelagic animals such as wahoo, tuna, billfishes, and marine mammals. It is a facultative ectoparasite, which means that it feeds on the flesh of other species causing them harm but not death and it is not dependent on these species for survival.
A dark patch on the ventral surface of the cookiecutter shark resembles a smaller fish when viewed from below and is thought to lure larger fish and marine mammals that may be swimming beneath it. When this sneaky predator attacks its prey, it grabs hold of the flesh with its lips and bites using its small, sharp upper teeth to grip the prey while it cuts the flesh with the large, serrated lower teeth. The cookiecutter shark then spins its body to remove a “cookie-shaped” plug of flesh which it swallows before releasing its prey.
Unlike other shark species that lose teeth individually, the teeth of the cookiecutter shark are shed as a single unit. The bottom teeth are swallowed, possibly to help maintain calcium levels in the body.
Cookiecutter sharks are ovoviviparous. Hatching takes places between 12-22 months with 6-12 pups per litter. When the young emerge, they are fully developed and able to hunt for food by themselves. Males mature at 36 cm and can grow to a size of 42cm. Females mature at 39 cm and can reach up to 56 cm.
Ovoviviparous: eggs are retained within the body of the female in a brood chamber where the embryo develops, receiving nourishment from a yolk sac. This is the method of reproduction for the “live-bearing” fishes where pups hatch from egg capsules inside the mother’s uterus and are born soon afterward. Also known as aplacental viviparous.
Conservation Status & Comments