Wednesday, August 15, 2012

Greenland Shark

Somniosus microcephalus
Today's Shark is one of my all time favorites-- they are just so unique! Greenland Sharks live farther north than any other Shark species in existence, swimming in the cold waters of Greenland, Iceland, and the North Atlantic. They can also grow to lengths over 20ft, allowing them to rival the Great White in size.

Greenland Sharks are such unusual creatures. While many other Sharks species are quick moving, these icy giants swim very very slowly (only around 1mph!). They also spend a great deal of time not moving at all-- another name for these guys is "Sleeper Shark" since they are so frequently inactive.

Don't let their slowness fool you! Greenland Sharks are still predators! They feed primarily on fish, but are also able to snatch up unsuspecting sea mammals as well. Horse, Polar Bear, and Reindeer remains have all been found in Greenland Shark stomachs, though how much of that was carrion is not quite known.

Greenland Sharks are solitary, but that doesn't mean that they are alone! They have a really bizarre relationship with a tiny crustacean known as Ommatokoita elongata. These copepods feed on the Sharks' eyes. The Sharks have impaired vision, since their corneal tissue is being gobbled up, but they don't use their eyesight all that much anyway. Besides, the partnership isn't completely one-sided. The parasites are bioluminescent, a trait that helps the Sharks to attract food!

The lifespan of the Greenland Shark is still a bit mysterious. Know one really knows how long they can live or when they reach maturity, but we do know that they grow very slow. A tagged Shark was re-captured 16 years after its original identification, and had only grown 8cm in that time-span (from 2.62m to 2.7m).

And before I leave you with a video of one of these guys, one final fact-- Greenland Shark skin is toxic! But that doesn't keep people from eating it. The skin is considered a delicacy in Greenland and Iceland, and must be repeatedly boiled in order to be safe for consumption.


IUCN Status : Near Threatened
Location : North Atlantic
Size : Length up to 21ft (6.4m)
Classification : Phylum : Chordata -- Class : Chondrichthyes -- Order : Squaliformes
Family : Somniosidae -- Genus : Somniosus -- Species : S. microcephalus

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