A shrimp from 50 million BC and other miracles of the sea

A census of ocean life has revealed a treasure chest of living jewels ranging from a mighty microbe as big as a fingernail to a furry crab and a giant lobster. Scientists have documented scores of new species of fish, crustaceans and plankton during this year's global survey of marine life - which included the discovery of deep-sea shrimps that can live at 80C.

Published today, the latest results of the census, which is in the sixth of its 10 years, highlight the environmental extremes where sea life can thrive.

The hot shrimps were photographed near a thermal vent on the seabed 3 kilometres (1.8 miles) below the surface. Scientists found that the temperature of the fluids billowing out of the vent were up to 407C - high enough to melt lead.

Using deep-sea submersible robots, the scientists recorded shrimps, mussels and clams living on the wall of the vent's chimney where they had to juggle temperatures ranging from a near-freezing 2C to a near-boiling 80C.

"All somehow tolerate an environment of extreme temperature changes within a few centimetres, and high concentrations of heavy metals from the vent fluids," said Ron O'Dor, a senior scientist on the Census of Marine Life.

"We knew that some microbes could live at this temperature but these are relatively big animals. At this point, we really don't know how they are able to survive such high temperatures. We would like to find this out," Dr O'Dor said.

On another expedition, scientists suspended an underwater camera down a hole drilled through 700 metres of ice floating above a column of seawater that had not seen light for many thousands of years.

It was one of the darkest marine habitats imaginable, yet an "astonishing community" of species had made this unlit environment their home, Dr O'Dor said.

"One of the clearest messages to emerge from the latest study is that there are no deserts in the ocean. Everywhere we look, we find evidence of life," he said.

In one of the deepest surveys, five kilometres below the surface of the Sargasso Sea in the North Atlantic, the scientists found a diverse array of rare zooplankton - microscopic animals near the bottom of the marine food chain.

They identified more than 500 species of zooplankton, including 12 that are probably new to science, which live by either eating each other or surviving on the organic matter that falls like snow from above.

On another survey, off New Jersey, scientists identified a single shoal of fish consisting of 20 million individuals covering an area as big as Manhattan island - one of the most abundant explosions of marine life ever documented.

"Each census expedition reveals new marvels of the ocean, and with the return of each vessel it is increasingly clear that many more discoveries await marine explorers," said Fred Grassie, the chairman of the census's steering committee.

The 20th expedition, led by the German research ship Polarstern, is currently under way off Antarctica. In total, the census has built up an online library of more than 10 million distribution records covering more than 78,000 species.

One of the most surprising discoveries was finding a living "Jurassic shrimp" that was thought to have gone extinct 50 million years ago. Neoglyphea neocaledonica was found alive and well on an underwater peak in the Coral Sea off north-east Australia.

The shrimp's discoverers said that finding the crustacean rivals the catching of living specimens of coelacanth, a prehistoric fish that was only known from the fossil record until the first one was caught in 1938.

Another surprising discovery was a single-celled "macro microbe" measuring 1cm across thanks to its plate-like shell composed of mineral grains. The microbe, a new species of protozoan called Xenophyophore, was found in Nazare Canyon off Portugal at a depth of 4.3 km where the pressure is strong enough to crush metal.

A rock lobster found off Madagascar may the largest of its kind. Its main body spans half a metre.

Near Easter Island in the Pacific, census researchers discovered a new species of furry crab that was so unusual it warranted an entirely new family name - Kiewaidae - after the Polynesia goddess of shellfish. Its second name is hirsuta, in honour of the crab's hairy appearance.

In an expedition to the mid-Atlantic ridge, a range of underwater mountains and valleys, scientists identified 300 different species of fish, some of them not seen since a similar expedition in 1910. Comparisons of species abundance with historical records suggested that many life forms are suffering, especially those being targeted by the fishing industry. "The historical studies of the Census for Marine Life agree with recent studies showing steep declines of most wild populations of marine animals that people eat," said Dr Grassle.

"The past richness of the oceans in many near-shore regions is hard for people today to believe," he said.

Historians working for the census reconstructed the abundance of life in 12 estuaries and coastal seas around the world. They found that habitat destruction had depleted 90 per cent of important species, and eliminated 65 per cent of seagrass and wetland habitats, as well as degrading water quality substantially.