Monday, June 25, 2012

Cookiecutter Shark

Isistius brasiliensis
Today's animal is no joke! Though they only grow to be about a foot and a half long, they can do some really amazing looking damage to much larger sea creatures! Cookiecutter Sharks get their name from their relatively unique jaws and what they do with them. They have large, powerful sucking lips, a row of narrow teeth on the top, and a row of much larger, knife-like teeth on the bottom. Like other sharks, they regularly replace their teeth. However, instead of losing a single bottom tooth at a time, they replace the entire row at once! Old teeth are swallowed, giving the Cookiecutters a good source of Calcium.

Cookiecutter Sharks attract their much larger prey using bioluminescent photophores (which grow bright green). The bigger sea creatures will go after the shark, but in a twist they will become the actual prey. The Cookiecutter will latch on with its mouth, spin its body around, and remove a perfectly circular chunk of flesh (just like a cookie cutter does to dough). Seals, Marlins, Tuna, Whales, and larger Sharks have all been found with these circular chunks taken out of them. Cookiecutters have even taken bites out of rubber domes in submarines!

Cookiecutter Sharks are found in tropical and temperate oceans all over the world, and they undergo daily migrations between shallow and deep water. During the day they can be found as far as 2-3 miles down, but during the day they move toward the surface in order to feed.

The question that I'm sure many of you are asking is "what about people? Do they bite people?" The answer to this (99.9%) no. There has only been one documented case ever of a Cookiecutter Shark biting a human, and that occurred in Hawaii in 2009. Before that only two other instances of bites were recorded, but both were incidents where a person died in the water and bitten post-mortem.

IUCN Status : Least Concern
Location : Temperate and Tropical Oceans Worldwide
Size : Length up to 22in (56cm)
Classification : Phylum : Chordata -- Class : Chondrichthyes -- Order : Squaliformes
Family : Dalatiidae -- Genus : Isistius -- Species : I. brasiliensis

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