But because researchers were unable to collect specimens, they still cannot say what exactly these sponges and other critters could eat. Some sponges filter organic debris from the water, while others are carnivores, partying with small animals. “That would be your headline of the year, “says Christopher Mah, a Smithsonian marine biologist who was not involved in the research.”Killer sponges, living in the dark, cold recesses in Antarctica, where no life can survive“.
And Griffiths and his team also can’t say yet whether mobile creatures like fish and crustaceans also live around the rock (the camera didn’t see any of them), so it’s unclear if the sessile animals they face some kind of predation. “Do they all eat the same food source?” Griffiths asks. “Or do some of them get nutrients from each other? Or are there more mobile animals providing food to this community? “These are all questions that only another expedition can answer.
It seems that the sedimentation around the rock is not very heavy, so the animals are not in danger of being buried. “Something like the Goldilocks is happening,” says Griffiths, of the seemingly fortuitous location of the rock, “where he has enough food and has nothing to want to eat, as far as we know, and is not buried by too much sediment.” . (In the sediment surrounding the rock, the researchers also noticed ripples that are normally formed by currents, thus reinforcing the theory that food is being transported here from afar).
Nor is it clear how these stationary animals came about in the first place. “It was something very local, where did they jump from a local rock to a local rock?” Griffiths asks. Alternatively, perhaps their parents lived on a rock hundreds of miles away — where the ice shelf ends and more typical marine ecosystems begin — and released their sperm and eggs to travel through the currents.
Because Griffiths and his colleagues do not have specimens, they also cannot say how old these animals are. Antarctic sponges have been known to live for thousands of years, so it is possible that this is a really ancient ecosystem. The rock may have been planted alive a long time ago, but currents have also refreshed it with extra life over the millennia.
Researchers also can’t say if this rock is an aberration or if these ecosystems are really common under the ice. Perhaps the geologists were not very lucky when they dropped the camera on the rock; perhaps these animal communities are a common feature of the seabed beneath Antarctic ice shelves. There would certainly be plenty of room for these ecosystems: these floating ice shelves stretch for 560,000 square miles. However, through previous holes, scientists have only explored an area below them equal to the size of a tennis court. So they may be in numbers and we haven’t found them yet.
And maybe we run out of time to do it. This rock may be closed to less than half a mile of ice, but this ice is increasingly endangered on a warming planet. “There is the potential that some of these large ice shelves may collapse in the future,” says Griffiths, “and we could lose a unique ecosystem.”
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