Hidden depths: what really lives under the ocean

The biggest ever survey of the world's oceans has shone a light on the darkest recesses of our planet, writes Steve Connor

Everywhere they looked, they found life. From the coldest waters of the poles to th e hottest of hot spots near deep-sea volcanic vents, scientists discovered thriving communities of marine organisms. In the Coral Sea off Australia they found a pink-spotted shrimp that was thought to have been extinct for 50 million years, while off the coast of Madagascar they spotted a new species of large lobster, the zoological equivalent of finding a new monkey in the US.

Scientists yesterday announced the completion of a 10-year survey of the world's oceans - the First Census of Marine Life - in a scientific tour de force involving the global cooperation of more than 2,700 researchers. The $650m (£430m) project involved more than 540 expeditions, with 9,000 research days at sea and countlessmore in laboratories.

The result is the formal description of more than 1,200 new species, with another 5,000 potential new species still waiting to be analysed.

Overall, the census scientists estimate there to bemore than 1 million species of marine animals, with only about a quarter being formally described in the scientific literature. They also reckon there are up to 1 billion kinds of marine microbes, making up about 90 per cent of marine life by weight, and equivalent in mass to about 35 elephants for every one of the 6.8 billion people on the planet.

Off the coast of Chile, the census foundmats of marine microbes covering an area of the seabed as big as Greece. At the other end of the scale they found large predatory fish, such as sharks and tuna, that regularly migrate across some of the biggest oceans.

"Life if much richer in the oceans than we expected," said Ian Poiner, head of the Australian Institute of Marine Science and a leadingmember of the census. "We also found that the oceans had changed farmore than expected, earlier than expected and quicker than we expected," he said.

Despite the census, there are still vast swathes of the ocean that remain a mystery. Some 20 per cent of them have never been investigated scientifically and about half have only been subjected to minimal research.