Olivia: Glaciers might look like lifeless expanses of ice, but these frozen wastelands actually support some pretty unique ecosystems. Hidden in silt-filled puddles are whole food webs of tiny organisms, which manage to thrive there. And someday, they could help jump-start the colonization of land left bare by retreating glaciers.

Cryoconite is a dark-colored, windblown dust that settles on the surface of glaciers. It’s made up of rock particles, soot, and the occasional microbe. The word “cryoconite” literally means “cold rock dust.” And it was coined in 1870 by Arctic explorer A. E. Nordenskjold, who noticed the grimy stuff while traveling across the Greenland Ice Sheet.

Cryoconite’s dark color absorbs the heat of the sun like a black t-shirt in the summer. And the ice underneath it melts, creating a small pool with a layer of silt at the bottom. That’s how you get what’s known as a cryoconite hole. They’re typically only fifteen to twenty centimeters deep, but they can grow to be several meters across. The combination of shelter and liquid water create a unique micro-habitat on the otherwise inhospitable surface of the glacier. And soon, organisms start to move in.

The first colonizers are photosynthetic microbes called cyanobacteria, which are blown in by the wind. They start converting the sun’s energy into biomass that other organisms can eat, and a whole ecosystem begins to form. Fungi, algae, and other bacteria eat the cyanobacteria, and those, in turn, are munched on by tiny animals.

A 2014 review of published studies on cryoconite holes on five continents found descriptions of 25 invertebrate species from 5 different branches of the animal kingdom. These creatures included insect larvae and worms, but there were also other, less well known types of animals.

There were rotifers, for example — microscopic animals with wheel-like rings of cilia around their mouths. Researchers had also found copepods, the small crustaceans that inspired the look of the character Plankton in SpongeBob SquarePants. And there were tardigrades, everyone’s favorite tiny, adorable, and super-hardcore water bear.

Some species of these animals have never been found anywhere but in cryoconite holes, and there are probably a lot more that we haven’t even discovered yet, because there haven’t been that many studies on these ecosystems. Even plant seeds can find refuge in cryoconite holes and remain viable there for a long time, though they can’t really sprout unless they find their way back into soil.

In 1999, a scientist collected some sediment from a hole in the ice on a remote island off the tip of an Antarctic Peninsula. From a seed in his sample, he managed to germinate something totally unexpected -- a fern native to Africa, which must have been carried there by the wind. So cryoconite holes provide an environment where all kinds of living things can survive. But they also might be changing the environment around them by fueling faster glacial melt.

Many of the species that live in these holes are dark, which helps them resist damage from ultraviolet radiation and absorb additional heat. As more and more holes form, more swarms of dark, heat-absorbing creatures move in, speeding up melting and creating even more holes to colonize. In the short term, more holes mean more habitat, which could lead to a population boom for these organisms. But as the surface area of glaciers continues to contract, they could be in trouble.

Still, some scientists think that cryoconite holes could help kick-start new ecosystems as retreating glaciers leave new expanses of bare soil. If the microbes, dormant seeds, and other bits of life in cryoconite sediment are deposited on the ground as their glacial homes melt, they might take hold there and start all over again.

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