Monday, November 1, 2010

November 1, 2010 : Whale Fall

Whale Fall

Whale fall is the term used for a whale carcass that has fallen to the ocean floor. Whale falls were first observed in the 1980s, with the advent of deep-sea robotic exploration.

When a whale dies in shallow water, its carcass is typically devoured by scavengers over a relatively short period of time—within several months. However, in deeper water (depths of 2,000 m/6,600 ft or greater), fewer scavenger species exist, and the carcass can provide sustenance for a complex localized ecosystem Some of the organisms that have been observed at whale falls are squat lobsters, bristleworms, prawns, shrimp, lobsters, hagfish, over periods of decades.Osedax (bone-eating worms), crabs, sea cucumbers, octopuses, clams, and even deep-sea sleeper sharks. Whale falls are often inhabited by large colonies of tubeworms. Over 30 previously unknown species have been discovered at whale falls.

A whale fall was first observed by marine biologists led by University of Hawaii oceanographer Craig Smith in 1987, discovered accidentally by the submersible Alvin using scanning sonar at 1,240 m (4,068 ft) in Santa Catalina, California Basin. Whale falls have since been found by other scientists, and by military submarines. They can be found by using side-scan sonar to examine the ocean floor for large aggregations of matter.

The first sign that whale carcasses could host specialized animal communities came in 1854 when a new mussel species was extracted from a piece of floating whale blubber. Beginning in the 1960s, deep sea trawlers unintentionally recovered other new mollusk species including limpets (named Osteopelta) attached to whale bones.

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