On glaciers,balls of dust and moss make a cozy home

Now balls of moss on glaciers are joining this strange list. The clumps,known as glacier mice,have been found to contain miniature ecosystems. And even in freezing temperatures,scientists found,the inhabitants manage to thrive.

In high winds glacier mice,which form when clumps of dust and organic debris develop a layer of moss over time,hop across vast sheets of ice. Because glaciers are in constant motion and are frequently blasted by strong winds,these clumps roll around a bit like tumbleweed,or dust bunnies,and the moss ends up growing on all sides.

After years of growth,the clumps look like mouse-size green balls of vegetal fluff,thus their name. Yet in spite of all the information that has been collected about how glacier mice form and get around,their innards remained a mystery.

Keen to better understand them,Steve Coulson,an arctic biologist at the University Center in Svalbard,Norway,decided to turn his attention toward the guts of the bizarre formations. He and a colleague,Nicholas Midgley,at Nottingham Trent University in England,knew that the mice often accumulated a lot of dust in their travels and could potentially function like roving sponges,soaking up water wherever they went.

To explore these possibilities,Midgley went to the Falljokull glacier in southeastern Iceland. He collected 10 glacier mice for closer examination and stuck probes in five others that would measure their internal temperatures over a two-week period.

They report the discovery of a new ecosystem in a paper in the June issue of Polar Biology. Inside the mice,the researchers found Collembola (six-legged insectlike creatures commonly known as springtails),tardigrades (eight-legged moisture-loving creatures called water bears) and nematode worms.

And contrary to what the team expected,these animals were thriving inside the glacier mice; with up to 73 springtails,200 tardigrades and 1,000 nematodes being found in just a single mouse.

The animals’ success made sense when Coulson took a look at data from the probes. Compared with the temperature of the glacier,which was 0 degrees Celsius,the mouse temperatures ranged from 2 to 10 degrees Celsius. In addition to the warmth,each of the collected mice carried about a gram of water—just enough to keep the tiny environment perpetually moist.