If you do much winter hiking, you will often find tiny black soot-like dots in the deep snow boot prints you have made. Few of us pay any attention to those little dots, but a closer look is well rewarded.
Because those microscopic dots are really little animals and interesting animals at that. You’ll often get a real surprise if you point the tip of your ski pole at one of them: it may leap as much as several inches. For an animal of that size, that high jump surely rates as Olympic for it can measure as much as a hundred times its own length.
That little athlete is a springtail or snowflea. You will note that I have been careful to record it as a snowflea, not a snow flea, the single word indicating (to entomologists at least) that they are not true fleas. In fact, they are not even insects and have been recently assigned to various families in a separate arthropod order of their own. And wow, are there a lot of them: 675 North American species and enough individuals to make them one of the most common animals in the world, one estimate suggesting that there are 100,000 per square meter of ground. The one you are probably seeing in this region is Hypogastura nivicola, but there are many other possibilities.
If you look at one of these tiny quarter-inch-long animals with a hand lens, you will see what looks a bit like a clawless crayfish, but with six legs. You may not see its forked tail, formally called a furcula, because it is normally bent beneath its body. In fact, that “springtail” is normally kept hooked to its belly. It is from that grip that it is suddenly released to produce that spectacular leap. (Scientists have timed that snap at a 58th of a second; most of us would say quite fast.)
Okay, we see these strange creatures in the winter. If there are so many, why don’t we see them in other seasons? They are there all right, but they inhabit the leaf litter and soil as well as moss cushions, fallen wood, grass tufts and ant nests. In those regions their small size and generally dark coloration makes them much harder to see than against the white snow.
And how can they live in the snow when the rest of us are freezing? Because springtails produce their own antifreeze, a protein rich in the amino acid glycine. Glycine prevents the formation and enlargement of ice crystals, enabling these creatures to keep on munching organic materials despite the bitter cold. You’ll see them most often on warmer days when the snow is melting because they are rising to the surface in search of new food sources.
I leave you with good news! There is no need to fear the snow flea. They don’t bite and they are actually very good for the environment!