Senin, 13 Juli 2009

Bowhead Whale

The bowhead is one of the largest of the baleen whale species. Adults average nearly 19 m long (65 ft.) and may weigh more than 60 t (66 tn.).

Its high-arching mouth ("bowhead") is distinctive, and the ponderous head forms more than one-third of its body length. Large sheets of baleen suspended from the upper jaw are used as screens for catching its food, mainly shrimp-like crustaceans known as "krill".

Some Arctic adaptations include:

  • thick blubber that provides the animal with food reserves and insulation against cold seas
  • an absence of a dorsal fin, which is useful for moving among ice floes
  • a massive head that can break through ice up to 0.6 m (2 ft.) thick when it is necessary to create breathing holes.

This slow-moving whale inhabits the Arctic Ocean and the sub-Arctic waters of the north Atlantic and Pacific Oceans. They cruise along at 2 to 4 knots, and sound for up to 30 minutes.

These whales are among the longest-lived mammals; they are still growing after age 50, and have been proven to live well beyond 100 years.

Whaling for the bowhead began near Spitsbergen as early as 1611 and continued until the early 1900s. Around that time the demand for whalebone dwindled, and the number of animals became too low for hunting them to be of economic interest.

The bowhead has been protected by the International Whaling Commission since 1937. However, native peoples are still allowed to hunt them for food. Aside from humans, the bowhead's only other predator is the killer whale.

Bowhead populations seem to be recovering well in the Bering, Chukchi and Beaufort Seas, but recovery has been slower in the Baffin Island, Greenland and Spitsbergen regions, where whaling was more intensive and carried on over a longer period. The species remains endangered, with approximately 8000 bowheads in existence today.

source : http://www.sdnhm.org, http://nature.ca, Youtube



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