This undated photo released by Census of Marine Life and the Woods Hole Oceanographic Institution shows a transparent sea cucumber, Enypniastes, creeping forward on its many tentacles at about 2 cm per minute while sweeping detritus-rich sediment into its mouth at 2,750 meters in the Northern Gulf of Mexico. Thousands of marine species eke out an existence in the ocean's pitch-black depths by feeding on the snowlike decaying matter that cascades down, and even sunken whale bones, according to a report released Sunday, Nov. 22, 2009.

Photograph: Larry Madin/Wood Hole Oceanographic Institution/guardian.co.uk