The waters below Antarctica are amongst the most inhospitable environments on our planet – or so we thought.
It’s pitch dark, and temperatures are subzero; yet, when scientists drilled through an Antarctic ice shelf far from light or warmth, they found a seafloor boulder that’s home to several species we may have never seen before.
A few of the organisms have been seen in similar locations, but this discovery marks the first time stationary creatures that live their lives attached to one place, such as sponges, have been found in this hostile environment.
“This discovery is one of those fortunate accidents that pushes ideas in a different direction and shows us that Antarctic marine life is incredibly special and amazingly adapted to a frozen world,” said biogeographer Huw Griffiths of the British Antarctic Survey.
The Antarctic ice shelves are permanent, floating rafts connected to the main landmass of the Antarctic continent, and they can be absolutely huge. In all, they constitute over 1.5 million square kilometres – about a third of the Antarctic continental shelf.
Because of how unwelcoming the environment below them is, and how hard it is to get to, we’ve explored very little of it. Generally, scientists bore holes in the ice and lower equipment down to take a gander at what’s down there.
From eight of these borehole surveys, we know that there is life under the ice, usually in the form of small mobile creatures such as fish, jellies, worms, and crustaceans. Filter feeders such as sponges were highly unexpected here, so far from regions where photosynthesis is possible.
But below the Filchner Ice Shelf – 260 kilometres (160 miles) from the ice shelf front, under 890 metres of ice, at a seafloor depth of 1,233 metres – that’s exactly what Griffiths and his colleagues found. Attached to the rock, they found one sponge on a stalk, 15 more sponges without stalks, and 22 unidentified stalked organisms that could be sponges, ascidians, hydroids, barnacles, cnidaria, or polychaetes.
“Our discovery raises so many more questions than it answers, such as how did they get there?” Griffiths said.
“What are they eating? How long have they been there? How common are these boulders covered in life? Are these the same species as we see outside the ice shelf or are they new [ … ]