1 - 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 grow 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."