An unexpected, thriving ecosystem.A diverse group of creatures beneath an Antarctic ice shelf could give pause to researchers who infer past ecological conditions from fossils found in such sediments. In December 2003, researchers drilled a hole through the 480-meter-thick Amery ice shelf The Amery Ice Shelf () is a broad ice shelf at the head of Prydz Bay between the Lars Christensen Coast and Ingrid Christensen Coast. It is part of Mac Robertson Land. in Antarctica to get a look at the ocean bottom. At the drill site, 100 kilometers from open ocean, they expected to see a barren seafloor. How wrong they were. Video of the ocean bottom at a depth of about 775 in revealed a wealth of creatures, says Martin J. Riddle, a marine biologist marine biologist specialist in the biology of marine life. at the Australian Government Antarctic Division in Kingston, Tasmania Kingston is a suburb and region on the outskirts of Hobart, Tasmania, Australia. Nestled 15km south of the city between and around several hills, Kingston is the council seat of its wider municipality, the Kingborough Council, and today serves as the gateway between Hobart and the . On the 2-square-meter patch of seafloor within camera range, the team identified more than two dozen familiar-looking species of invertebrates, including sponges, mollusks, sea urchins sea urchin, spherical-shaped echinoderm with movable spines covering the body. The body wall is a firm, globose shell, or test, made of fused skeletal plates and marked by regularly arranged tubercles to which the movable spines are attached. , and a sea snail snail, name commonly used for a gastropod mollusk with a shell. Included in the thousands of species are terrestrial, freshwater, and marine forms. Some eat both plant and animal matter; others eat only one type of food. . Most of the creatures typically filter food and nutrients from the water or scavenge scav·enge v. scav·enged, scav·eng·ing, scav·eng·es v.tr. 1. To search through for salvageable material: scavenged the garbage cans for food scraps. 2. the ocean bottom. Scientists hadn't expected currents to bring much food to the site under the ice shelf, says Riddle. However, the team reports in the January Paleoceanography that instruments on the probe measured currents strong enough to bring in microplankton that form the base of the site's food chain. The researchers warn that if paleontologists were to find the remains of such a complex community of organisms in ancient sediments, they'd probably assume that the site hadn't been covered by ice. While that would seem a reasonable assumption, says Riddle, "it's obviously wrong.... These creatures are no different from those that live in open water at that depth." |
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