Whale fall

Whale fall is the term used for a whale carcass that has fallen to the ocean floor. [ [http://www.columbia.edu/~rwb2103/whale/whalefallintro.html Whale fall intro ] ] Whale falls were first observed in the 1980s, with the advent of deep-sea robotic exploration. [University of California at Berkeley site]

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 2000m or greater), fewer scavenger species exist, and the carcass can provide sustenance for a complex localized ecosystem over periods of decades, or possibly centuries. [ [http://www.livescience.com/animals/070518_anemone_whale.html New Creature Found Living in Dead Whale | LiveScience ] ]

Some of the organisms that have been observed at whale falls are squat lobsters, "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 in 1987, discovered accidentally by the submersible Alvin. 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.

Some scientists speculate that certain deep-sea species may use whale falls as stepping-stones to extend their range and colonize other ecosystems, such as hydrothermal vents and cold seeps. Given that whale deaths occur at locations that are largely random, carcasses are believed to exist at many locations on the seabed, like oases in the nutrient-poor abyssal plain, with average spacings estimated at 25 km. Marine biologists sometimes transport dead whales that have washed up on coastlines, towing them offshore to create a whale fall at a known location that can then be studied over a long period of time.

Similar ecosystems exist when other large volumes of nutrient-rich material fall to the sea floor. Sunken beds of kelp create kelp falls, and large trees can sink to create wood falls.

Notes

External links

* [http://www.westnurc.uaf.edu/dwnlds/Smithecologywhalefalls.pdf Craig Smith's paper on whale fall ecology (University of Hawaii)]
* [http://www.nurp.noaa.gov/Spotlight/Whales.htm Article from NOAA's Undersea Resarch program (NURP)]
* [http://nationalzoo.si.edu/Publications/ZooGoer/2005/2/whaleworms.cfm Robin Meadows, "A Whale of a Tale"]
* [http://www.sciencedaily.com/releases/2007/09/070913165159.htm (Science Daily), University of California, Berkeley, "Fossil Whale Puts Limit On Origin Of Oily, Buoyant Bones In Whales"] 14 September 2007