Ice worms are annelids of the genus Mesenchytraeus, and represent the only annelid worms known to spend their entire lives in glacial ice. They include Mesenchytraeus solifugus, M. harrimani, M. kuril, M. maculatus and M. obscurus.
The first ice worms species were discovered in 1887 in Alaska, on the Muir Glacier. These glacier ice worms can be found on glaciers in Alaska, Washington, Oregon and British Columbia. They have not been found in other glaciated regions of the world. The specific name solifugus is Latin for "sun-avoiding," as ice worms retreat underneath the ice before dawn. Enzymes in ice worms have very low optimal temperatures, and can be denatured at even a few degrees above 0 °C (32 °F). When ice worms are exposed to temperatures as high as 5 °C (41 °F), their membrane structures disassociate and fall apart (i.e., "melt") causing the worm itself to "liquify." Ice worms are several centimeters long, and can be black, blue, or white in color. They come to the surface of the glaciers in the evening and morning. On Suiattle Glacier in the North Cascades, population counts indicated over 7 billion ice worms.
It is not known how ice worms tunnel through the ice. Some scientists believe they travel through microscopic fissures in ice sheets, while others believe they secrete some chemical which can melt ice by lowering its freezing point, like an antifreeze. They feed on snow algae.
Ice worms in culture
Scottish-born Canadian poet of the Yukon Robert W. Service wrote the poem, The Ballad of the Ice-worm Cocktail, in which a fake ice worm made of spaghetti is the subject of a bar bet. This may have contributed to the impression that ice worms are mythical creatures. An old Canadian song When the Iceworms Nest Again, jokes about how cold it is in northern Canada. (Titles vary, using "iceworms," "ice worms" and "ice worm.") There is a different song of the same name by the Canadian group Jenny Omnichord, which is highly factually accurate. Organisms similar to ice worms have appeared in science fiction in the short story "Glacial" by Alastair Reynolds and the novel Fallen Dragon by Peter F. Hamilton. In the annual February Ice Worm Festival of Cordova, Alaska, a long imitation ice worm is paraded through the streets like a Chinese new year dragon dance.
- Kathryn A. Coates, Jan M. Locke, Brenda M. Healy & Mark J. Wetzel (August 26, 2008). "The aphanoneuran and clitellate Annelida occurring in the United States and Canada: families Enchytraeidae and Propappidae". University of Illinois at Urbana-Champaign. Retrieved January 22, 2010.
- Shain, Daniel H.; Carter, Melissa R.; Murray, Kurt P.; Maleski, Karen A.; Smith, Nancy R.; McBride, Taresha R.; Michalewicz, Lisa A.; Saidel, William M. (2000). "Morphologic characterization of the ice wormMesenchytraeus solifugus". Journal of Morphology 246 (3): 192–7. doi:10.1002/1097-4687(200012)246:3<192::AID-JMOR3>3.0.CO;2-B. PMID 11077431.
- Service, Robert William (1910). The Trail of '98. New York: Grosset & Dunlap. p. 209.