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The remote and forbidding waters of Antarctica's Southern Ocean are the ancestral homeland for most of the deep-sea octopus species in the world, a team of researchers has discovered.

Just as humans moved out of Africa, deep-sea octopuses swam north from Antarctica to populate the oceans of the world, say scientists involved in an ambitious international project to produce the first marine life census of the planet.

They collected tissue samples from Antarctic octopuses, and compared their genetic material with 30 other deep-sea species from around the globe. Their analysis showed they all had a common Antarctic ancestor, and are related to a species that still lives in the Southern Ocean.

They say their findings bolster the theory that many of the creatures that adapted to the dark waters of the deep ocean have Antarctic origins.

They probably began heading north 30 million years ago when the Antarctic cooled and a large ice sheet grew, producing an expressway of northbound flowing water with high concentrations of oxygen and salt.

Unlike octopuses that live closer to the surface, deep-sea species don't have ink sacs, said Ron O'Dor, a Canadian biologist who is one of the senior scientists in charge of producing the census, which is to be released in October of 2010. “If you live in the dark, ink doesn't do you much good.”

The Antarctic origin of octopuses is one of thousands of discoveries that have been made by 2,000 researchers from 82 countries involved in an unprecedented effort to document and track the animals that inhabit the oceans.

Paul Snelgrove, a deep-sea biologist at Memorial University in St. John's, leads the team that has been given the challenging job of integrating 10 years of findings.

“The census may offer a new map, a new biogeography, of all ocean life,” he said.

Researchers are mapping the range and distribution of animals in the oceans, the diversity of species, their abundance and how that has changed over time.

Said Dr. O'Dor: “We are approaching a global picture of the movements of animals, whether swirling in eddies the size of Ireland or commuting 8,000 kilometres across ocean basins.”

The researchers are planning, in addition to a scientific tome, a number of volumes for armchair explorers, including a coffee table book and a children's version.

Some of the most startling discoveries have been in the polar seas.

In the dark waters beneath the Antarctic ice, researchers found scores of species they had never seen, including strange jellyfish and other gelatinous organisms that thrive without light.

In the Arctic, another expedition found a pink octopus close to the North Pole.

Yesterday, the census released its fourth annual progress report, which includes new details about the tiny creatures that live in briny channels in Arctic sea ice.

Unique forms of algae, tiny crustaceans and jellyfish-like animals thrive in brine that is six times saltier than regular sea water. Temperatures usually hover around -25 Celsius.

But sea ice is melting rapidly, and these creatures may disappear before scientists can figure out what role they play in the food chain.

“One of things that we lose by melting the Arctic is this whole ecosystem that lives in the ice,” Dr. Snelgrove said.

Other researchers are also reporting discoveries about what they describe as a “new continent,” the Mid-Atlantic Ridge.

“It is the largest mountain range in the world. It runs all the way from north of Iceland, down through the middle of the North Atlantic, straight on down past the Azores, into the south Atlantic and into the Southern Ocean,” Dr. O'Dor said.

A Norwegian ship surveying the northern part of the ridge has found that it is not a barren, mid-ocean desert, but is richly populated with crustaceans, fish and many other species, including 20 that appear to be new to science.