Marine species suggest Antarctic "cradle of life"

WASHINGTON (Reuters) - Carnivorous sponges, 585 new species of crustaceans and hundreds of new worms have been discovered in the dark waters around Antarctica, suggesting these depths may have been the source of much marine life, European researchers reported on Wednesday.

The team, who scooped samples from as deep as 20,000 feet , found unexpectedly rich diversity of animal life.

Many belong to species found around the world, notably in the Arctic, while others appear to be unique to the deepest Antarctic waters, the researchers reported in the journal Nature.

The unique species tend to be the kind that do not spread easily, which suggests the deep, cold southern oceans may have been the source of many types of marine life, the researchers conclude.

"The Antarctic deep sea is potentially the cradle of life of the global marine species. Our research results challenge suggestions that the deep sea diversity in the Southern Ocean is poor," said Angelika Brandt of the Zoological Institute and Zoological Museum at Germany's University of Hamburg.

"We now have a better understanding in the evolution of the marine species and how they can adapt to changes in climate and environments," Brandt, who led the expedition, said in a statement.

Among the new creatures they documented are a gourd-shaped carnivorous sponge called Chondrocladia; free-swimming worms and 674 species of isopod, a diverse order of crustaceans that includes woodlice, also commonly called pillbugs, sea lice or sea centipedes.

Of the isopod crustaceans, 585 species had never been seen before.

Between 2002 and 2005, researchers sampled water and the sediment from 2,500 to 20,000 feet in the deep Weddell Sea and adjacent areas.

Their catch was surprisingly rich.

"What was once thought to be a featureless abyss is in fact a dynamic, variable and biologically rich environment," Katrin Linse, a marine biologist from the British Antarctic Survey, said in a statement.

The researchers said the Weddell Sea is an important source of deep water for the rest of the ocean. Species can enter the depths of the Weddell sea from shallower continental shelves.

Animals that spread easily, such as the single-celled Foraminifera, were similar to those found in other oceans.

"The isopods, ostracods (seed shrimp) and nematodes, which are poor dispersers, include many species currently known only from the Southern Ocean," the researchers wrote.