What might life on another planet look like? What the British Antarctic Survey came across earlier this year (2021) may shed some light on that age-old question. As Wired reports, the Society wanted to study the history of the floating shelf. Instead, they came across strange creatures that live under a half-mile of solid ice!
But let’s take things from the beginning. The Society started an arduous journey into the Filchner-Ronne Ice Shelf’s history. To do this, they wanted seafloor sediment, which is locked under a half-mile of ice.
To get to the bottom of it (pun intended), they had to pump 20,000 liters of hot water through a pipe lowered down a borehole. It took them 20 hours to melt through the ice, inch by inch, until they finally pierced through the shelf:
Video: Dr. Huw Griffiths/British Antarctic Survey
Unfortunately, when they lowered the collector that would get them the sediment they needed, it came back empty: the place they had dug ended up on a rock.
What was on the rock was a big surprise: life.
Not to Tell Life Its Business but…
When Huw Griffiths of the British Antarctic Survey watched the footage, he noticed a kind of film on the rock, likely a layer of bacteria known as a microbial mat. An alien-like sponge and other stalked animals dangled from the rock, while stouter, cylindrical sponges hugged the surface. The rock was also lined with wispy filaments, perhaps a component of the bacterial mats, or perhaps a peculiar animal known as a hydroid.
The rock they had accidentally discovered is 160 miles from daylight—that is, the nearest edge of the shelf, where ice ends and the open ocean begins. It’s hundreds of miles from the nearest location that might be a source of food—a spot that would have enough sunlight to fuel an ecosystem, and be in the right position relative to the rock for known currents to supply these creatures with sustenance.
Not to tell life its business, but it’s got no right being here.
We can say for certain that these animals are living in total darkness, which is fine—plenty of deep-sea critters do the same. But animals that live sessile (read: stuck in place) existences on the deep seafloor must rely on a fairly steady supply of food in the form of “marine snow.” Every living thing swimming in the water column above must one day die, and when they do, they sink to the depths. As the corpses descend and decompose, other creatures pick at them and fling off particles, tiny morsels that accumulate even on the deepest of seafloors. (When a whale dies and sinks, by the way, it’s epically known as a “whale fall.”)
This works in most parts around Antarctica, where the waters are incredibly productive. Tiny critters known as plankton feed all kinds of fish, which feed large marine mammals like seals. All this activity produces detritus—and dead animals—that one day become marine snow.
However, the Antarctic critters on this particular rock don’t live under a bustling water column. They live under a half-mile of solid ice. And they can’t roam away from their rock in search of food. “The worst thing in a place where there’s not much food, and it’s very sporadic, is to be something that’s glued to the spot,” says Griffiths. So how on Earth could they be getting sustenance?
Since the researchers couldn’t collect specimens, they can’t yet say what exactly these sponges and other critters could be eating. Some sponges filter organic detritus from the water, whereas others are carnivorous, feasting on tiny animals. “That would be sort of your headline of the year,” says Christopher Mah, a marine biologist at the Smithsonian, who wasn’t involved in the research. “Killer Sponges, Living in the Dark, Cold Recesses of Antarctica, Where No Life Can Survive.”
It does appear that sedimentation around the rock isn’t very heavy, meaning the animals aren’t in danger of being buried. “It’s kind of a Goldilocks-type thing going on,” says Griffiths of the rock’s apparently fortuitous location, “where it’s got just enough food coming in, and it’s got nothing that wants to eat them—as far as we can tell—and it’s not getting buried by too much sediment.”
A Tennis Court under the Sea
Right now, we have more questions than answers. Because Griffiths and his colleagues don’t have specimens, they can’t 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 truly ancient ecosystem. Perhaps the rock was seeded with life long ago, but currents have also refreshed it with additional life over the millennia.
The researchers also can’t say whether this rock is an aberration, or if such ecosystems are actually common under the ice. Maybe the geologists didn’t just get extremely lucky when they dropped their camera onto the rock—maybe these animal communities are a regular feature of the seafloor beneath Antarctica’s ice shelves. There’d certainly be a lot of room for such ecosystems: These floating ice shelves stretch for 560,000 square miles. Yet, through previous boreholes, scientists have only explored an area underneath them equal to the size of a tennis court. So it may well be that they’re out there in numbers, and we just haven’t found them yet.
And we may be running out of time to do so. This rock may be locked away under a half-mile of ice, but that ice is increasingly imperiled on a warming planet. “There is a potential that some of these big ice shelves in the future could collapse,” says Griffiths, “and we could lose a unique ecosystem.”
However, don’t despair: the chances we may find something similar in Europa are pretty good as far as I’m concerned!
Read the full article on Wired and, if this got you inspired, happy writing!