Students Probe Peculiar Ice Worms in Alaska's Glaciers

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A year and a half ago, Shain spent the summer trekking, boating, and camping across Alaska's coastal glaciers to find out everything he could about the distribution, habitat, and life cycles of ice worms. The National Geographic Society funded the trip.

"Ice worms are just remarkable creatures," said Shain. "You could be walking along a glacier at around 7 at night and the glacier is perfectly white. At around 7:30, there are so many ice worms coming up to the surface that they change the color of the glacier to a sort of black plaid, as if you had put thousands of black threads on a white surface.

"You can't move without stepping on hundreds of them," he said.

"Dark Threads in the Ice"

The coastal glaciers that serve as ice worm habitat extend from Mount Rainier in Washington State to Alaska.

Ice worms, which are a relative of the common earthworm, have no eyes, so they don't see images, but they respond to light and dark. At a little less than an inch long (one to two centimeters), they are often described as looking like pieces of dark thread in the ice.

They have big mouths, said Shain, and their primary food source is the red algae that grows on glaciers. Their ideal temperature is zero degrees Celsius (32 degrees Fahrenheit); at 5 degrees Fahrenheit they start to disintegrate.

They spend their days burrowing up and down through the ice. "They definitely operate on some kind of Circadian rhythm," said Shain, "moving up when it's dark and down when it's light."

Ice worms propel themselves using setae, extremely small bristles that protrude from the sides of their bodies. Wiggling through fractured ice and snow crystals, they burrow as deep as three to six feet (one to two meters) beneath the surface of the ice.

They can live in colonies of a few hundred thousand to 20 million, covering an area as large as 30 acres. No one knows how long they live. Beyond the occasional bird or two, the only threat to their existence may be global warming.

"Alaska's coastal glaciers are right on the edge, at about 32 degrees Fahrenheit, and most are retreating," said Shain. "If it gets any warmer, they're going to start melting even more quickly. As their habitat goes, so too will the ice worms."

Classroom Science

The ice worms have a very large pore on the top of their heads; its function is unknown, although the worms may use it to excrete a mysterious substance. Some other worms have head pores, but these pores tend to be smaller and situated on the back of their heads.

"We don't really know what they may be excreting or what the purpose might be," said Shain. "One idea is that it could be some kind of mucous to protect them from drying out or maybe provide lubrication through the ice. Another possibility—you have to just throw ideas out there in science—is that it could be salt to help melt the ice in front of them."

It's this trial-and-error, one-idea-then-another aspect of science that the Jason Expeditions are able to convey to students through their interactive programs.

Watch Jason highlights on television in the United States on the National Geographic Channel, January 28 to February 2 and February 4 to 8 from 5-6 p.m. ET/PT. The Frozen World expedition can also be followed on the Jason Web site.

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