World's octopuses share a common 'living' ancestor

London, Nov 10 : A new study has shown that many of the world's deep-sea octopuses evolved from a common ancestor that still exists in the icy waters of the Southern Ocean.

According to a report by BBC News, the findings form part of a decade-long global research programme known as the first Census of Marine Life (CoML), set to be completed in late 2010.

The project, which began back in 2000, involves more than 2,000 scientists from 82 nations.

The research into the evolution of deep-sea octopuses was part of a programme called the Census of Antarctic Marine Life (CAML).

The project, which began back in 2000, involves more than 2,000 scientists from 82 nations.

Researchers suggest that octopuses evolved after being driven to other ocean basins 30 million years ago by nutrient-rich and salty currents.

"Many of these octopuses were collected from the deep sea by a number of the CoML's different projects," Don O'Dor, CoML's co-senior scientist told BBC News.

"All of that material was brought together and made available to Dr Jan Strugnell, a biologist at the British Antarctic Survey (BAS) in Cambridge, and she used this material to carry out DNA studies," he said.

"She was looking at the relationship between these different deep-sea octopuses and how they originated. She has been able to trace the timeline for their distribution back 30 million years to a common ancestor," he added.

The species could all be traced back to a shallow-water octopus called Megaleledone setebos, which is only found in the Southern Ocean.

Dr O'Dor added that the BAS researcher's work also enabled her to identify how changes in the region's ocean played a pivotal role in the development of the new species, especially the emergence of a "thermohaline expressway".

"When you get an increase in sea ice, fresh water forms ice crystals and leaves behind high-salinity, high-oxygen water, which is denser than the surrounding sea water, so it sinks," he explained. "It gets mixed by sea currents and flows into all of the deepest parts of the ocean," he added.

"At the time this process started, there was no oxygen at the bottom of the ocean, so it brought oxygen into these areas, and we can now see that the octopuses moved out from the Antarctic into deeper water," he further added.

ANI