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Snowfleas
| Article
# : |
14008 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
2 / 1988 |
1,108 Words |
| Author
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Kenneth Christiansen
Kenneth Christiansen is professor of biology at Grinnell
College, Grinnell, Iowa. |
Late this winter, if you take a walk through the woods on a sunny day when the snow is still on the ground, you may see some dark blue patches on the snow. Look at these patches more closely and you will probably find that they consist of thousands of tiny insectlike creatures. These minute arthropods, commonly called snowfleas, have only become visible to you because their sheer numbers swarming beneath the snow have brought them to the surface.
Snowfleas belong to the large group of species known as collembolans or springtails. Considered collectively, these diverse species are among the most numerous and ubiquitous creatures on the surface of the earth. Several thousand different species of the order Collembola have been identified, but their small size (generally less than three millimeters) makes identifying them quite difficult. Indeed, of all the species of collembolans, snowfleas are perhaps the most conspicuous because of their pattern of emerging in vast numbers from beneath the snow on a warm winter's day.
A good many species of collembolans thrive in the soil litter, where they feed on fungi and bacteria. Under the ideal conditions often available in the winter when predators are scarce, they may multiply greatly in the leaf litter under the snow. Then, on a warm, sunny day, they may increase their level of activity so much that they appear to boil out onto the snow's surface. Their vast numbers and their sudden appearance cause some people to think something is amiss, but there is no cause for alarm. Snowfleas are totally harmless to man, plants, or animals. The best control measure is the simplest: Wait a day and they will be gone. A few will make it back into the soil, but most will die, shrivel up, and blow away.
Snowfleas and their relatives are found throughout the world. Some species, such as the European "glacier flea," are active on snow or ice at temperatures well below freezing. This species feeds on pine pollen plant fragments and other debris trapped on the glacier surface. Similar species have been identified in North America and elsewhere, including a record number of species found above 21,000 feet on Mount Everest. Collembolans are also abundant at high latitudes; and they extend closer to the poles than most land animals. In some arctic areas they are so dominant that the soil consists largely of their droppings.
All collembolans have three pairs of legs and most have a peculiar structure near their end called a furcula, which is used for jumping: hence the name springtail.
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