The newly discovered creatures include a carnivorous sponge that uses tentacles to grab its tiny crustacean prey, 300 new species of isopods -- marine crustaceans related to garden wood lice -- and a 15-inch deep-sea octopus, all living about a half-mile to four miles below the ocean's surface.
"We were astonished by the number of new species," researcher and lead author Angelika Brandt, a marine biologist at the Zoological Museum of Hamburg in Germany, told Agence France-Presse. The researchers had expected to find the same lack of biodiversity seen in the Arctic Ocean around the North Pole, she said.
Instead, they found an area teeming with life. There are two possible reasons for the difference, Brandt told AFP. First, the Antarctic oceans are older than the Arctic, giving marine life more time to evolve -- at least 20 million years. Also, the area plays a critical role in deep-water ocean circulation, and the large quantities of water that circulate through "might nourish the animals better than in any other deep sea," she suggested.
In fact, Brandt said, the new discoveries suggest that this part of the Antarctic Ocean could be the cradle of deep-sea marine life worldwide. The researchers examined the DNA of many of the creatures and found genetic links to species as far away as the tropics and the Arctic.
The researchers also found intermingling between species that evolved in shallower water and those that evolved in the deep ocean. That is likely because the cycle of glacial advances and retreats might have driven shallow-water species to colonize the deep waters when the ice was at its greatest extent, the researchers theorize.
This intermingling also was possible because the difference in temperature between the deep and shallow water is smaller in Antarctica than in other areas, researcher Katrin Linse told the Times of London.
In Antarctica, deep water is about 36 degrees Fahrenheit, while shallow water might reach 30 degrees Fahrenheit. In tropical areas, in contrast, deep waters might be 40 degrees, while surface waters might reach 75 degrees. So, Linse said, shallow-water animals in the Arctic wouldn't have to overcome a great temperature difference to colonize the deep water.
The research, published Thursday in the journal Nature, comes from a series of three expeditions between 2002 and 2005 aboard the German research vessel Polarstern.