On a sunny winter day you may notice tiny, dark flecks bouncing on the snow, often concentrated near the bases of trees or collecting in footprints and other indentations. While snow fleas are the size of actual fleas, don’t worry about infestation — they’re not interested in either you or your pets (please don’t take that personally). Try not to step on them, as they’ve given us the means to improve both organ transplantation and ice cream.
Snow fleas, a type of “springtail,” were classified as insects until recent DNA sequencing pegged them as another type of arthropod called a hexapod. Apparently there’s now heated debate as to whether springtails constitute a class or a sub-class. You have to love scientists. First they study an obscure arthropod to develop life-saving technology, then come to fisticuffs over labeling it.
Whatever their label, snow fleas are beneficial in many ways. As decomposers of organic matter, they’re important in the formation of healthy topsoil. They and their hexapod cousins are one of the most abundant types of soil ‘animals,’ numbering around 100,000 individuals per cubic yard of topsoil.
Besides eating algae, fungi, nematodes, protozoa and a wide range of organic matter, they consume organisms and spores that cause damping-off wilt and other plant diseases. In fact, springtails are being studied for their potential to control plant diseases in greenhouses.
Snow fleas produce a unique glycine-rich protein that keeps ice from forming inside cells at very cold temperatures. This newly-discovered molecule is unlike any previously known protein, and is the basis for research on more efficient storage of transplant organs. Organs can be stored much longer at below-freezing temps with this antifreeze protein. Eventually we may see ice cream that never forms ice crystals no matter how long it sits neglected in the freezer.
Springtails lack a respiratory system and must breathe through their skin. As a result, they’re quite vulnerable to drying out, and hop around to find moist, sheltered places as well as things to eat. While a true flea uses its tarsi, or toes, to vertically jump seven inches (roughly the equivalent of a person jumping 500 feet straight up using only their toes), a snow flea is not nearly so athletic. It either crawls along or uses its two tail-like appendages to bounce a small fraction of a flea-jump.
During warmer months snow fleas and other springtails are even more active than in winter, although without a white background for contrast they’re hard to see. They forage extensively in the humus layer and move all through the soil, even deep down. Springtails can be found throughout the forest canopy as well as on water, where surface tension keeps them from sinking. If you go out with a flashlight some June night you can see springtails bopping about on standing water.
Just hearing the word ‘flea’ can set folks on edge and start them scratching, so it’s unfortunate about the snow fleas’ name. Try thinking of them as springtails, and keep an eye out on bright winter days for these jittery critters that help make topsoil, and could one day help save your life, or at the very least, make for crystal-free ice cream.
Photo courtesy University of Nebraska.