The accidental discovery of marine organisms on a boulder on the seabed below 900 meters from the Antarctic ice shelf, led scientists to reconsider the boundaries of life on earth.
Researchers stumbled upon the life-bearing rock after sinking a borehole through nearly a mile of the Filchner-Ronne ice shelf into the southeastern Weddell Sea to obtain a sediment core from the seabed.
As the rock dusted off their chances of acquiring the core, footage from a video camera sent through the hole captured the first images of organisms trapped on a rock beneath an ice shelf.
“It’s a bit bonkers,” says Dr Huw Griffiths, a marine biogeographer from the British Antarctic Survey. “We would never have thought within a million years of looking for this kind of life, because we did not think it would be there.”
Ice shelves form when frozen water flows from the interior to the coast and floats to the surrounding sea. As the ice flows over the land, it can pick up rocks that are embedded in the base of the ice shelf before falling to the seabed.
Although a few small mobile organisms, such as fish, worms, jellyfish, and krill, have been found far below the ice shelves, stationary filter feeds have never been found that survive by ingesting food that falls on them. Their absence led many scientists to suspect that the total darkness, the lack of food and the -2C temperature were too hostile for them.
Photos and videos of the rock block show that there are at least two types of sponge, one of which has a long stem that opens into a head. But other organisms, which can be tube worms or stalked squirrels, also grow on the rock. Details of the discovery were published in Frontiers in Marine Science.
The isolated rock community lies 500 meters below the ice plank and 260 km from the nearest open water. Due to the strong currents in the area, the food they ingest – perhaps dead plankton – is thought to be carried between 370 and 930 miles before it is reached.
“It’s by far the furthest under an ice shelf we’re ever seen of these animals being filtered,” Griffiths said. ‘These things are stuck on a rock and are only fed when something floats together.
‘It was a real shock to find them there, a very good shock, but we can not do DNA tests, we can not work out what they ate or how old it is. “We do not even know if they are new species, but they definitely live in a place where we would not expect them to live,” he said.