Slideshow: Deep-sea Spiders Have a Snack

Three thousand meters below the ocean's surface, a remotely operated vehicle has captured never-before seen images of deep-sea spiders feeding in their natural habitat. These sluggish, long-legged spiders, which occupy a distinct class of arthropods from land spiders, survive on sea anemones in a submarine canyon off the Central California coast.

Researchers from the Monterey Bay Aquarium Research Institute tracked two species of sea anemones and two species of sea spiders from the genus Colossendeis during 12 visits over a 4-year period. The submarine robot observed the spiders' proboscis piercing wilted pom-pom anemones among the clam fields, wood debris, and whale carcass remains in the submarine canyon. The spiders adopted many feeding strategies, from sucking with their proboscis on sedentary anemones or detached tentacles, to devouring anemones as they rolled together in the currents. The team, led by evolutionary biologist Robert Vrijenhoek, reports the findings in the fall issue of the Journal of Invertebrate Biology.

Vrijenhoek and colleagues have previously observed boneworms nibbling on whale bones that had fallen to the sea floor. The rare sightings of boneworms and sea spider feasts support the idea, the authors say, that the sea floor is more of an oasis than the nutritional desert some had believed.

Anemone tentacles make a tasty snack (Flash slideshow). A deep-sea pycnogonid, or sea spider, holds two detached tentacles of a sea anemone in its mouth amid the mollusk shells and whale bones that have settled on the sea floor. Image courtesy of the Monterey Bay Aquarium Research Institute. © 2009 MBARI

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