But because the researchers couldn’t collect specimens, they can’t yet say exactly what these sponges and other critters might eat. Some sponges filter organic waste from the water, while others are carnivorous and feed on small animals.Which would be some kind of headline of the year, ”said Christopher Mah, a marine biologist at the Smithsonian who was not involved in the study.Killer Sponges, Living in the Dark, Cold Recesses of Antarctica, Where No Life Can Survive
And Griffiths and his team also can’t say yet if mobile creatures like fish and crustaceans also live around the rock – the camera hasn’t caught a glimpse of it – so it’s not clear if the sessile animals are facing some form of predation. . “Are they all eating the same food source?” Griffiths asks. “Or do some of them get nutrients from each other? Or are there somehow more mobile animals feeding this community? “These are all questions that only another expedition can answer.
It appears that the sedimentation around the rock is not very heavy, meaning the animals are in no danger of being buried. “It’s kind of a Goldilocks-ish thing,” Griffiths says of the rock’s seemingly accidental location, “where it gets just enough food, and it has nothing that it wants to eat – as far as we can tell – and it’s not going to be. buried by too much sediment. ”(In the sediment that surrounds the rock, the researchers also noted ripples usually formed by currents, reinforcing the theory that food is carried from far here.)
Nor is it clear how these stationary animals got there at all. “Was it something very local, where they hopped a bit from local boulder to local boulder?” Griffiths asks. Alternatively, their parents may have 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 in the current.
Since 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’s possible that this is a really ancient ecosystem. The rock may have been littered with life long ago, but currents have also refreshed it with extra life over the millennia.
The researchers also cannot say whether this rock is an aberration, or whether such ecosystems are really common under the ice. Perhaps the geologists were not only very lucky when they dropped their camera on the rock – perhaps these animal communities are a regular part of the seabed beneath the Antarctic ice shelves. There would certainly be a lot of room for such ecosystems: These floating ice shelves stretch for 560,000 square miles. But through previous boreholes, scientists have only explored an area below the size of a tennis court. So it may well be that they come in numbers, and we just haven’t found them yet.
And we may have too little time to do that. This rock may be trapped under half a mile of ice, but that ice is increasingly endangered on a warming planet. “There is a possibility that some of these large ice shelves could collapse in the future,” Griffiths said, “and we could lose a unique ecosystem.”
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