Tiny animals dominate deep-sea trenches

Colonies of tiny, soft-bodied animals thrive in the deepest parts of the Pacific Ocean, Japanese researchers reported on Thursday.

Colonies of tiny, soft-bodied animals thrive in the deepest parts of the Pacific Ocean, Japanese researchers reported on Thursday.

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Many of the creatures they dredged up are one-celled animals called foraminifera, which surprised the researchers because they do not normally live deep in the ocean and because they typically have hard shells.

The little organisms may have slowly adapted to the dark and high pressure found in the trenches 35,000 feet (10,000 metres) under the ocean, the researchers report in Friday's issue of the journal Science.

Yuko Todo of Shizuoka University in Japan and colleagues used the KAIKO Remote Operated Vehicle to sample the very deep trenches of the western Pacific, which they said reached their present depths 6 to 9 million years ago.

"The lineage to which the new soft-walled foraminifera belong includes the only species to have invaded fresh water and land, and analysis of the new organisms' DNA suggests they represent a primitive form of organism dating back to Precambrian times from which more complex multichambered organisms evolved."