But since the researchers were unable to collect any specimens, they cannot yet say what exactly these sponges and other creatures might be eating. Some sponges filter organic detritus from the water, while others are carnivorous and feast on tiny animals. “This would sort of be your title of the year, ”says Christopher Mah, a Smithsonian marine biologist, who was not involved in the research. “Killer sponges, living in the dark and cold corners of Antarctica, where no life can survive. “
And Griffiths and his team can’t yet say if mobile creatures like fish and crustaceans also live around the rock – the camera hasn’t seen any – so it’s unclear whether the sessile animals face a kind 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 more mobile animals around that provide food for this community? These are all questions that another expedition can answer.
It appears that the sedimentation around the rock is not very heavy, which means that the animals are not at risk of being buried. “It’s kind of a Goldilocks type thing,” Griffiths says of the seemingly fortuitous location of the rock, “where there’s just enough food going in, and there’s nothing going on. eat them – as far as we can tell – and it’s not buried by too much sediment. (In the sediment surrounding the rock, the researchers also noticed ripples typically formed by currents, further supporting the theory that food is carried here from afar.)
It’s also not clear how these stationary animals got there in the first place. “Was it something very local, where they went from a local rock to a local rock?” Griffiths asks. Alternatively, maybe their parents lived on a rock hundreds of miles away – where the pack ice ends and the more typical marine ecosystems begin – and released their sperm and eggs to travel in the currents.
Because Griffiths and his colleagues don’t have any specimens, they can’t tell how old these animals are either. We know that Antarctic sponges have lived since thousands of years, so it is possible that this is a really old ecosystem. Perhaps the rock was sown with life a long time ago, but the currents have also refreshed it with additional life over the millennia.
Researchers also cannot say whether this rock is an aberration or whether such ecosystems are in fact common under ice. Maybe the geologists weren’t extremely lucky when they dropped their cameras on the rock – maybe these animal communities are a regular feature of the seabed under the ice shelves of the Antarctic. There would certainly be plenty of room for such ecosystems: these floating ice shelves extend over 560,000 square miles. Yet, thanks to previous drilling, scientists have only explored an area below equal to the size of a tennis court. So it may be that they are numerous and that we have not yet found them.
And we may be running out of time to do it. This boulder may be trapped under half a mile of ice, but this ice is increasingly under threat on a warming planet. “There is a potential that some of these large ice shelves in the future will collapse,” Griffiths says, “and we could lose a unique ecosystem.
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