Bizarre New Deep-Sea Creatures Found Off Antarctica
for National Geographic News
|May 16, 2007|
A treasure trove of more than 700 new species has been uncovered in the dark depths of oceans surrounding Antarctica, researchers report. (See a photo gallery of the finds.)
Heart-shaped sea urchins, carnivorous sponges, and giant sea spiders the size of dinner plates are among the surprising discoveries brought up from the seafloor about 2,300 to 19,700 feet (700 to 6,000 meters) beneath the Antarctic waves.
"We were astonished by the enormous biodiversity we found in many groups of species," said study lead author Angelika Brandt, a marine biologist at the University of Hamburg in Germany.
"We used to think that, with decreasing nutrient and food availability, there might cause a decrease in biodiversity toward the Poles," Brandt said.
"There were a lot of species we hadn't seen before, because so little was known before we started," said study co-author Brigitte Ebbe, a marine biologist at the German Centre for Marine Biodiversity Research in Willhelmshaven.
The research was part of the Antarctic Benthic Deep-Sea Biodiversity Project, or ANDEEP. An international team of researchers from 14 organizations embarked on three ANDEEP expeditions between 2002 and 2005 on the German research vessel Polarstern in the Weddell Sea, east of the Antarctic Peninsula.
(See a map of the region.)
The project has made a major contribution to the Census of Marine Life (CoML) programme, a global collaboration among thousands of researchers who aim to make a detailed record of all ocean life by 2010.
"In other oceans the number of species drops the deeper you go," said study co-author Katrin Linse, a marine biologist at the British Antarctic Survey.
"But in the Southern Ocean we found the opposite trend."
The Southern Ocean includes the Indian, Atlantic, and Pacific Oceans surrounding Antarctica.
(Related: "Video: Antarctica Diving Opens Up World of Strange Creatures" [January 31, 2006].)
Around 300 species of isopod, a diverse group of marine crustaceans related to garden wood lice, live in the shallow Antarctic waters.
However, they look different from wood lice. One common family of isopods can even swim.
"With the deep-sea samples, suddenly the number of isopods rocketed up to at least a thousand," co-author Linse said.
In addition to the wealth of species found in the oceans near Antarctica, lead author Brandt noted the deepest part of the seafloor, farther north, revealed even more isopod species, from 60 to 70 degrees south latitude.
Most of the new species are very small—less than 0.2 inches (about 5 mm)—and nearly all are ghostly white.
"It's so deep and dark down there, you dont need any color," said co-author Linse.
The ANDEEP cruises were also the first to look at the DNA of the Southern Ocean's deep-sea species.
"The great advantage in the Antarctic is that the water column is cold all the way up," said Brandt, "so we can bring material up on deck and extract DNA before it becomes damaged by heat."
The study revealed that similar-looking specimens of foraminifera, single-celled amoeba-like creatures found at the North and South Poles, are genetically the same species—a shock to scientists.
Even more surprising, said Brandt, was the discovery of a much stronger gene flow in foraminifera from the Antarctic to the Arctic, but not vice versa.
That's because deep Antarctic water flows northward, supplying much of the deep water in other world oceans.
The study appears in tomorrow's issue of the journal Nature.
Colin Summerhayes, executive director of Scientific Committee on Antarctic Research (SCAR), was not involved in the study.
He noted that the Ecology of the Antarctic Sea Ice Zone project, another recently-completed program, also turned up high biodiversity under Antarctic sea ice.
"We now see that the notion of a latitudinal decrease in biodiversity towards the South Pole is rubbish," Summerhayes said.
"This current study confirms the trend we found in communities beneath the sea ice."
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