Mesenchytraeus solifugus
Encyclopedia
Mesenchytraeus solifugus is a species of Oligochaete
worms commonly called ice worm
s. Ice worms populate coastal glaciers in North America
from Alaska
to northern Washington State. They are the only known worm to spend their entire life in temperatures near 0 °C. Even if other places are equally cold, ice worms never venture onto any other terrain. They eat the abundant snow algae and pollen
carried by the wind.
Mesenchytraeus solifugus have a very narrow acceptable temperature range. Ice worms freeze at around −6.8 °C, and their bodies decompose after continuous exposure to temperatures above 5 °C. This decomposition process, known as autolysis, occurs when the cells produce digestive enzyme
s and self-destruct. The body literally melts.
Adult ice worms measure around 15 mm in length and about 0.5 mm in diameter. Their fluid and flexible body squeezes through air holes and tiny crevasses in ice.
The worms appear on the surface in high density; researchers have counted between 30 to 300 ice worms per square metre. On Byron glacier alone, researchers estimate the worms numbered around 30 million. The total number in all the coastal glaciers easily surpasses the entire human population.
Ice worms have heavy pigment
, absorbing all colours or reflecting dark brown. Yet strangely, they burrow into the glacier to avoid strong sunlight. Carlo Emery
named the species solifugus in 1898, meaning "fleeing from the sun".
In the summer, ice worms follow a diurnal cycle—at the first light in the morning, they sink into the glacier. A few hours before sunset, they poke out from the snow.
Ice worms can still be found in broad daylight. Many of them gather in glacial ponds or small streams. Scientists believe the water blocks out the sun's longer wavelength
s which the worms avoid, and the freezing water provides the worms with comfortable temperature.
In fast flowing glacial streams, an ice worm clings onto the icy surface. Researchers have observed the worms gyrate their head in the stream, possibly catching algae and pollens carried by the water. In still ponds, ice worms gather in bundles. Researchers speculate this has something to do with their reproduction. Ice worms do not graze in groups on the surface. The bonding in the still pond provides the rare opportunity for breeding.
Since in the winter the surface temperature on a glacier could reach −40 °C, scientists doubt the worms follow the diurnal pattern. The worms most likely remain below the surface. The snowfall provides insulation and the temperatures below maintain a stable 0 °C. Ice worms can still find plenty of algae in the firm layer, the layer of packed snow in transition to ice. Scientists know little about the ice worm during the winter as the inaccessibility of glaciers prevents further study.
It is believed that the ice worm has a life span of five to ten years. Laboratory worms survived in a freezer beyond one year without any food. Researchers are now investigating what prevents the worm from freezing at 0 °C. and looking for the evolutionary steps by which the ice worm diverged from other species. Understanding the ice worm’s secret could help preserve vital organs for transplant, and could aid in understanding of possible life forms on cold planets.
Oligochaeta
Oligochaeta is a subclass of animals in the biological phylum Annelida, which is made up of many types of aquatic and terrestrial worms, and this includes all of the various earthworms...
worms commonly called ice worm
Ice worm
Ice worms are species of the worm genus Mesenchytraeus that live in glacial ice. They include Mesenchytraeus solifugus, M. harrimani, M. kuril, M. maculatus and M. obscurus....
s. Ice worms populate coastal glaciers in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
from Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
to northern Washington State. They are the only known worm to spend their entire life in temperatures near 0 °C. Even if other places are equally cold, ice worms never venture onto any other terrain. They eat the abundant snow algae and pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
carried by the wind.
Mesenchytraeus solifugus have a very narrow acceptable temperature range. Ice worms freeze at around −6.8 °C, and their bodies decompose after continuous exposure to temperatures above 5 °C. This decomposition process, known as autolysis, occurs when the cells produce digestive enzyme
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
s and self-destruct. The body literally melts.
Adult ice worms measure around 15 mm in length and about 0.5 mm in diameter. Their fluid and flexible body squeezes through air holes and tiny crevasses in ice.
The worms appear on the surface in high density; researchers have counted between 30 to 300 ice worms per square metre. On Byron glacier alone, researchers estimate the worms numbered around 30 million. The total number in all the coastal glaciers easily surpasses the entire human population.
Ice worms have heavy pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
, absorbing all colours or reflecting dark brown. Yet strangely, they burrow into the glacier to avoid strong sunlight. Carlo Emery
Carlo Emery
Carlo Emery was an Italian entomologist.Born in Naples, Carlo Emery was professor of Zoology at the University of Bologna. He later worked in Geneva...
named the species solifugus in 1898, meaning "fleeing from the sun".
In the summer, ice worms follow a diurnal cycle—at the first light in the morning, they sink into the glacier. A few hours before sunset, they poke out from the snow.
Ice worms can still be found in broad daylight. Many of them gather in glacial ponds or small streams. Scientists believe the water blocks out the sun's longer wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
s which the worms avoid, and the freezing water provides the worms with comfortable temperature.
In fast flowing glacial streams, an ice worm clings onto the icy surface. Researchers have observed the worms gyrate their head in the stream, possibly catching algae and pollens carried by the water. In still ponds, ice worms gather in bundles. Researchers speculate this has something to do with their reproduction. Ice worms do not graze in groups on the surface. The bonding in the still pond provides the rare opportunity for breeding.
Since in the winter the surface temperature on a glacier could reach −40 °C, scientists doubt the worms follow the diurnal pattern. The worms most likely remain below the surface. The snowfall provides insulation and the temperatures below maintain a stable 0 °C. Ice worms can still find plenty of algae in the firm layer, the layer of packed snow in transition to ice. Scientists know little about the ice worm during the winter as the inaccessibility of glaciers prevents further study.
It is believed that the ice worm has a life span of five to ten years. Laboratory worms survived in a freezer beyond one year without any food. Researchers are now investigating what prevents the worm from freezing at 0 °C. and looking for the evolutionary steps by which the ice worm diverged from other species. Understanding the ice worm’s secret could help preserve vital organs for transplant, and could aid in understanding of possible life forms on cold planets.
Sources
- Hartzell, P. (2003). Glacial Ecology: North Cascades Glacier Macroinvertebrates. Retrieved on Oct. 21, 2005, from: http://www.nichols.edu/departments/glacier/bio/index.htm
- Pelto, M. S. (2003). Ice Worms (Mesenchytraeus solifugus) and Their Habitats on North Cascade Glaciers. A study by North Cascade Glacier Climate Project. Retrieved on Sept. 28, 2005, from http://www.nichols.edu/departments/glacier/iceworm.htm
- Shain, D. H., Carter M. R., Murray, K. P., Maleski, K. A., Smith, N. R., McBride, T. R., et al. (2000). Morphologic Characterization of the Ice Worm Mesenchytraeus solifugus. Journal of Morphology, 246, 192-197.
- Shain, D. H., Mason, T. A., Farrell, A. H., & Michalewicz, L. A. (2001). Distribution and behavior of ice worms (Mesenchytraeus solifugus) in south-central Alaska. Canadian Journal of Zoology, 79, 10, 1813-1821.