The mystery of the glacier worm, a ″ scientific paradox that experts are trying to unravel | Science and Ecology | DW

Ice worms were first discovered in 1887 on the Muir Glacier in Alaska. Since then, it has been observed how every summer – when the sun hits the glaciers directly – billions of thread-like black worms rise to the surface of the snow. And scientists still don’t know why.

Before the discovery, biologists viewed high altitude glaciers as arid places where life was essentially impossible. Now the black worms out of the iceMesenchytraeus solifugus) have been observed on most North American coastal glaciers in Alaska, British Columbia, Washington State and Oregon.

Its entire life cycle on ice

The creatures, which are about four inches long and as thin as dental floss, are the only worm species known to science that spends its entire life on ice, the report reports. LiveScience.

“They are incredibly fresh, abundant, and are the largest organism on Earth that spends its entire life cycle in ice,” says biologist Scott Hotaling of Washington State University at AccuWeather.

“When they are close, there are hundreds of them per square meter. You cannot walk without stepping on them … so it is something very dramatic when they are present,” he adds.

According to scientists, the tiny black worms emerge in the afternoons and summer nights to feed on algae, microbes and other debris on the surface. Then, at dawn, they sink again into the ice, and during the winter they disappear into the frozen depths.

These distant relatives of earthworms survive in layers of icy water in snow and ice, thriving at the freezing point of water. However, ice worms cannot survive freezing temperatures.

A mystery for scientists

So how do ice worms do? Scientists have discovered some of the tricks of these worms and found that it is surprisingly relevant and urgent to understand them, because, as the region’s glaciers shrink due to climate change, these worms are in danger of disappearing.

Hotaling has performed thermal tests and claims that ice worms can comfortably survive for at least a day or two in temperatures as low as 24 degrees Celsius, and although they thrive in temperatures around zero degrees Celsius, they die. when temperatures drop below this threshold.

“In a way, it is curious that this worm lives in ice and cannot survive frost, but it is also very interesting from an ecological point of view, since it lives very close to its lower thermal limit. “, explains Hotaling.

Paradoxically, it is when they emerge briefly in summer, and when exposed to wind at the surface, that they run the greatest risk of freezing. They stay warm enough to survive burial in ice.

“Think of it like living in an igloo,” Hotaling says. “There are 40 negative degrees on the outside, but there are probably zero degrees on the inside,” he adds.

Absorb heat from solar radiation

It’s not entirely clear to those who study these creatures why they come out yet, but Hotaling has a guess. According to the biologist, the worms are extremely tolerant of UV rays and he believes they go out to get heat energy from the sun and find food.

“They actually have a lot of pigments, which I think is largely to absorb heat from solar radiation and that’s why they come out to be on the surface, to get heat,” he said. he declares. AccuWeather, adding that it “helps their metabolism and various biochemicals while feeding on the soft top layer of snow.”

But what they do all winter is “the ultimate ice worm mystery,” he says.

NASA and the study of the existence of life in extreme environments

For its part, NASA has granted funding to evolutionary biologist from Rutgers University Dan Shain to investigate the survival of the ice worm under extreme conditions. And it was not for less: the space agency is interested in studying the existence of life in extreme environments, perhaps unraveling the mysteries of possible life on other planets or on frozen moons.

“If we are interested in finding life on ice-covered worlds, then understanding how life on Earth has evolved and adapted to life under these conditions is important to NASA,” said Michael New, scientist in astrobiology at NASA. NPR.

“We are trying to understand the distribution and extent of life on Earth to inform our ability to seek life elsewhere.”