Nov 22, 2009, 17:00 GMT
Washington - Marine scientists have identified 17,650 species in ocean depths so far down that light no longer penetrates, according to the newest update in the years-long census of marine life released Sunday.
The oddest of their finds included the jumbo Dumbo, a 2-metre-long creature that swims by flapping large ear-like fins, like the cartoon elephant. The rare octopod was found at 1,000 to 3,000 metres depth in the Mid-Atlantic Ridge, the Census of Marine Life said.
But researchers were also astonished to lift up a worm from 990 metres beneath the Gulf of Mexico, only to find crude oil streaming from both the animal and the open hole.
'The 'wildcat' tubeworm had hit a gusher and was dining on chemicals from decomposing oil,' the scientists said in a press statement.
The ongoing global Census of Marine Life is the first attempt to take stock of the world's oceans and their species, and has taken researchers into ocean regions rarely studied or visited. The census is to be published by October 2010 in an online encyclopaedia with a webpage for every species. Scientist expect that there will still be more than 1 million unknown ocean species at that point.
The report released Sunday documented the 17,650 species found deeper than 200 metres, the depth where darkness stops photosynthesis.
Nearly 6,000 of those species were found deeper than 1,000 metres, where marine life can be long-lived despite a meagre diet and often must rely on 'chemosynthetic' production of food instead of photosynthesis. Deep sea life can also survive if it has abundant food in higher layers that settles to the depths or that they can migrate to.
Scientists baited one trap with whalebone and sunk it in the Antarctic, where they found the region's first recorded whalebone- eating worm, Osedax, thought to only exist in the northeast Atlantic and the northern Pacific.
'To survive in the deep, animals must find and exploit meagre or novel resources, and their great diversity in the deep reflects how many ways there are to adapt,' said Robert Carney of Louisiana State University, co-leader of the group that studied life along the continental margins.
All told, 344 scientists from 34 nations - including Russia, Brazil, South Africa and Uruguay - have been working on this part of the project, the deep-sea census.
Species in depths up to 5,000 metres, where the water is ice cold and pressure 400 times that on the surface, were the most difficult to find. Researchers had to use remote-controlled high-tech devices like underwater vehicles along the rough, unpredictable ocean floors.
Chris German of Woods Hole Oceanographic Institution in Massachusetts worked at such depths and described how bad weather on the abyss of the Caribbean's Cayman Trough held up their work.
But a cup of deep-sea mud from such a sea bottom contained a rich ward - a collection of numerous small, millimetre-long living suprises.
'The deep sea is the Earth's largest continuous ecosystem and largest habitat for life. It is also the least studied,' said German.
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