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Specks in the Snow

By: Shelby Perry
February 5, 2018

Extreme close-up of a snow flea showing the sticky furcula at the end of its body. Photo by Charley Eiseman. For more visit his BugTracks blog.

Having grown up in rural Vermont, I first encountered snow fleas as a small child. At around six years old, I didn’t yet have a very strong concept of what fleas really were, only the rough idea that they were tiny jumping insects, and that we definitely didn’t want them. On this warm winter’s day these “fleas” were clustered around the base of a tree. They didn’t seem too interested in me, but I felt it was better to be safe than sorry, and so I moved on down the trail.

Some years later I came across some true fleas and to my surprise they looked very different from those little specks in the snow. If these were fleas, then what were those? I had to know.

It turns out snow fleas aren’t even closely related to true fleas. In fact, they are members of a family of arthropods known as springtails, so-called because they jump using an appendage on their abdomen called a furcula. This structure unfolds like a sprung mouse trap by quickly filling with fluid, and can catapult them up to 100 times their body length in a single jump. True fleas can jump even farther, but they use their hind legs to do so.

Jumping that far and landing on leaves or snow is tricky business, under most circumstances anything that small and solid would bounce when hitting a rigid surface like snow, but snow fleas can stick. They have a slick adaptation that helps them grab onto the ground when they land—three sticky vesicles that they can unfold from their anus (pictured). This little sticky tripod helps them land and then can be retracted while they explore their new setting. And finding a suitable location is important to snow fleas, as they lack a respiratory system and need to breathe through their skin, so they require moist substrates to keep from drying out.

Conglomerations of snow fleas photographed by Jon Leibowitz in the Split Rock Wildway.

Though they are most commonly associated with snow, snow fleas are actually even more active in the summer months—they are just much less visible in the dark environments of the soil and duff layer than they are on the surface of bright white snow. They eat organic materials like dead leaves, fungi, molds, and spores, and do not parasitize other animals the way true fleas do. In fact, springtails are important little decomposers that play a significant role in building soil and nutrient cycling.

Early this winter our new Executive Director, Jon Leibowitz, went on a day trip to the Split Rock Wildway in Essex, NY. Northeast Wilderness Trust stewards a collection of properties in this area aimed at preserving connectivity for the movement of wide ranging mammals through this predominantly agricultural landscape. Jon returned from this visit with photos of huge conglomerations of snow fleas clustered around tree trunks, showing the Wildway holds value for creatures both large and small.

 

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