"We are now reaching a stage of scientific consensus about this number," said Rolf Gradinger, a biological oceanographer at the University of Alaska, Fairbanks. "It will certainly still change over the next decades." As counting continues, scientists are trying to explain how each of the 235 species got to both ends of the Earth. Deep ocean currents probably transported small species that live on the seafloor, Gradinger said. Birds and whales, on the other hand, can migrate long distances on their own. And some species may date back to a time when the Earth was an entirely different place, before the continents shifted to their current locations and the climate became what it is today. "It's more than just: Here's a number," Hopcroft said. "Knowing the size of the number and who are the animals on the list will allow us to pursue some more interesting questions." With DNA analysis, for instance, scientists hope next to determine whether species that look the same actually are the same. The results of these studies could also reveal how long polar populations have been separated from each other, and how long it took them to split. In turn, that kind of information could help reveal fundamental facts about the history of the Earth, the oceans, and the environment. "The polar seas are at the extreme ends of the entire range of marine habitats," Gradinger told Discovery News. "We need to know how many of these life forms are unique to the polar seas to understand the impact of changing environments and human exploitation in these seas." Related Links: |
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