Monday, April 18, 2011

Springtails

More than an inch of rain fell Saturday night. Fortunately the fierce storms that hit the Carolinas brought only modest rain and no severe winds or funnel clouds. Sunday morning was bright and beautiful here.

Kodi and I walked a favorite trail at College Woods in Durham. Small streams ran high with the overnight rain and the Oyster River was high, fast, and silty. In some places water flowed over the trail, much to Kodi's delight. One such spot was covered in an amorphous black blob. A closer look showed a writhing mass of springtails. And you had to look close to notice, as these tiny insect-like creatures are just a couple millimeters long.




Springtails live in the leaf litter of moist soils, feeding on decaying vegetation. By some counts there may be 50,000 to 100,000 springtails per cubic foot of soil. The mass of springtails washed into a huge mass after the weekend rain surely numbered in the tens of thousands.

Typically I see springtails on a warm, late winter/early spring day when they emerge onto the white snow. This, along with their "hopping" behavior, led people to call them "snow fleas." The other occasion to see springtails is after a big rain, as on Sunday. Perhaps this is the main dispersal mechanism, as this population of springtails was washed into a new area, much farther from where they started.

Snow fleas have a furcula - an odd little appendage tucked under their abdomen. When released it lets them spring a few inches from where they started. An anti-freeze protein allows them to stay active in winter, when most insects would perish from the cold. Springtails are a type of hexapod, a predecessor of insects that date back to dinosaur days. An amazing little creature.

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