Tuesday, February 15, 2011

February 15, 2011 : Bluntnose Sixgill Shark

Bluntnose Sixgill Shark

The bluntnose sixgill shark,
Hexanchus griseus, often simply called the cow shark, is the largest hexanchoidshark, growing to more than 5.4 m (18 ft) in length.

The bluntnose sixgill shark is a member of the Hexanchidae family. Many of its relatives are extinct. The living species that are closest genetically include the dogfish, the Greenland shark, as well as other six- and sevengilled sharks. There are more closely related relatives in the fossil record than living species. Some of the shark's relatives date back to 200 million years ago. This shark is a notable species due to both its primitive and current physical characteristics.

This species typically inhabits depths greater than 90 m (300 ft), and has been recorded as deep as 1,875 m (6,150 ft). Like many deep-sea creatures, the bluntnose sixgill shark is known to undertake nightly vertical migrations (travelling surfaceward at night, returning to the depths before dawn).

The bluntnose sixgill shark can be seen at depths of 30 m (100 ft) and shallower during parts of the year in some specific places e.g. Flora Islet, near Hornby Island, Sightings during shallow evening dives in Whytecliff Park West Vancouver in British Columbia, in Puget Sound, Monterey Canyon off Monterey, California and in fjords in Norway. The sharks are deepsea sharks, but like most fish that prefer the deep, they come to the shallower depths to feed.

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