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Photo Essay
Under Antarctic Ice
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 ©2003 Norbert Wu/www.norbertwu.com

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In Explorer's Cove, soft corals (Gersemia antarctica) move around. Each is attached at the base to a small rock which stays buried in the sediment. Because the water in Explorer's Cove is nutrient-poor (oligotrophic), the Gersemia there derive at least a portion of their nourishment by bending down to lie flat on the substrate. They sweep around in an arc that way, using their polyps to sift microorganisms and organic matter out of the sediment. This in itself is a unique and remarkable behavior, unknown for a soft coral.

Then the Gersemia deflate and inflate the stalk to move along the bottom like an inchworm. When they reach a new spot, they repeat the process. They can move as much as ten feet in a 24 hour period. This is astounding behavior for an animal that is supposed to be sessile and has no brain to speak of.


--Norbert Wu