"They're literally, in places, heaped up upon each other," Rogers said. Crabs normally don't tolerate cold temperatures well, so the vents may be a warm haven for these crabs, Copley said.
Unlike vents in other oceans, the Antarctic vents lack tube worms, mussels and shrimp. Instead they harbor new species of barnacles and anemones, as well as a large brown spiral-shelled snail. The researchers even saw ghost-pale octopuses, which seemed drawn to the lights of the ROV.
"We were completely blown away by what we found," Copley said. "I've worked at vents in the Atlantic, the Pacific and the Indian Ocean, but these are the lushest, richest vents, in terms of life, that I've come across."
The discovery helps fill a gap in researchers' understanding of how deep-sea life disperses around the oceans, Rogers said. They had expected that the Southern Ocean would be a historical gateway for vent species to travel between the Atlantic, Pacific and Indian oceans, and there do seem to be some species, such as the yeti crab, that are related to species found at other vents. Those relationships seem to reach back into geological history, Copley said, when there was a connection between the Antarctic and the eastern Pacific.
But the vast differences between Antarctic vents and vents found elsewhere suggest that the area is not a gateway but a biological region in its own right, Rogers said. The cold Antarctic waters may act as a barrier to species that start their lives as swimming, feeding larvae, he said. On the other hand, larvae that carry their own food supply with them in eggs — known as lecithotrophic larvae — may be able to survive and disperse in the chilly Southern Ocean.
As humans increasingly exploit the deep seas for fish, oil and mining, understanding how species are dispersed is crucial, Copley said.
"Until we understand what governs the patterns of life at deep-sea vents, how interconnected their populations, how well life disperses from vent to vent, we can't make responsible decisions about how to manage these deep-ocean resources."
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