It's not a fast way to travel, dpa reported.
In fact, it takes several centuries for animals to get from one end of the world to the other.
That's the surprising conclusion by marine scientists, who have found that 235 species are identical in the Arctic and Antarctic oceans even though separated by 11,000 kilometres.
"This is much more than anyone expected," Ron O'Dor, senior scientist for the global Census of Marine Life, told Deutsche Presse- Agentur dpa.
The highway used by snail-like pteropods, worms and crustaceans consists of huge, very slow-moving icy currents spread over the globe on the bottom layers of the oceans that connect the two poles, biologist Russell Hopcroft told dpa.
O'Dor, a professor at Dalhousie University in Canada, and Hopcroft, a biologist at the University of Alaska in Fairbanks, were part of a team of thousands of researchers who, for eight and a half years, have been collecting data to explain the diversity and distribution of marine life.
The programme is to end in October 2010.
Over the last two years, there was a special focus on the polar regions as part of an extended International Polar Year that started in 2007 and ends in March.
In the Antarctic region alone, samples were collected from 1 million locations.
Finding species capable of living on both poles is the "rebirth of a historic idea," O'Dor said.
Early explorers had drawn pictures of animals from both poles and suggested that they were the same. "But we couldn't be sure whether their drawings were accurate," he said.
In addition, scientists were prejudiced against the idea of the species being exactly the same because of the physical differences between the Antarctic and Arctic.
To begin with, the Antarctic waters are much larger and have a greater range of light exposure than the Arctic.
In addition, the Arctic is fenced in by land mass while the Antarctic waters run free into the Indian, Pacific and Atlantic oceans.
Until this study, scientists believed the only species that could maintain exact identities at the opposite poles were marathoners like grey whales and birds that can travel swiftly.
The real surprise was these small invertebrates - the tiny snails, worms and crab-like species.
None of them can swim very fast by themselves. Generations of them live and die while they are moving from one pole to the other within the icy waters of the currents.
"It is not a high percentage of animals who are capable of living in these remote places," Julian Gutt, a scientist at the Alfred Wegener Institute in Bremerhaven, Germany, told dpa.
But these very few animals might in the future give scientists new clues about evolution.
Some of the species, which at first were thought to be similar, turned out to be two separate species after analysis of their genetics. This also is giving scientists new insights into how life and the planet developed.
"We can look backwards and find out how long ago those species separated," Hopcroft said. "That can tell us something about how the world was connected."
Polar species were able to live much closer together during the last Ice Age 18,000 to 20,000 years ago, when sheets of ice covered much of the earth and connected the polar regions.
"Ecologically, it might not appear very important that those similar-shaped species are in fact two species," Hopcroft said.
But Hopcroft added that if global warming affects both poles and kills nearly-similar species, "in fact two species - and not one - disappear."
Some of the identical species found both in Arctic and Antarctic waters might prove to in fact be quite cosmopolitan, Hopcroft pointed out.
"It is possible that they not only live on both poles, but that they also live in the deep waters of the oceans," he said.
So far, scientists don't know much yet about those depths.
"We don't have enough samples," Hopcroft said. "The problem is: very few people are willing to spend a lot of time one or two kilometers beyond the surface of the ocean and collect samples."