Friday, March 23, 2007
Biodiversity Corner: Springtail
The vernal equinox occurred on Tuesday marking one of the two points in the year when the sun spends the same amount of time above and below the horizon. It's officially spring, so what better topic than a springtail? And with the snow melting it is likely there are a lot of snow fleas, which are not fleas but a type of springtail, leaping about in our yards and woods.
Springtail diversity. There are around 6,000 known species of springtails, and they are found worldwide including Antarctica. There are at least 800 species in North America. If only a quarter of them are living in Carlisle I could, theoretically, run nothing but springtail columns for the next four or five years! Since I don't know how to identify them I am covering them here in one fell swoop.
Here's what we will be missing. They are colorful little things. They can be white, yellow, orange, metallic green, blue, lavender, gray, or red. They are primitive, six-legged wingless insects. The bodies can be long (for a springtail that means about a quarter inch) and slender or short and chubby, and they may be covered with bristles. The antennae can be short or long. The legs are short and not developed for jumping as in other jumping insects like fleas and grasshoppers.
When and where seen. Their habitats are as diverse as the species — they can be found in tropical rain forests, in snow banks, on the surface of water, in the soil, in leaf litter, and in fungi.
Last week before the snow I found dozens of dark blue springtails on a fallen branch in my back yard. In the warm part of January, there were hundreds of little black ones on the driveway around my neighbor's garage. Last spring I found thousands on the surface of a stream in the Conant Land. The water around the edges of the stream was completely covered with them.
Two years ago I found some chunky-bodied members of the Sminthuridae family lurking in the gills of a mushroom and sporting two big white spots on either side of their black bodies. The ones in the photo (above) are about one millimeter long and were found last spring on top of the leaf litter near a vernal pool in the Greenough Land. They are tricky little devils to photograph because they won't sit still. You are likely to notice them in late winter and early spring when they appear suddenly in huge populations called a Collembola "bloom." This often occurs on top of melting snow. It looks as though black pepper has been sprinkled on the snow. Another place they turn up this time of year is in buckets of maple sap.
Food chain. Springtails are an important component of the soil food web. In forest soils there can easily be pockets with 100,000 springtails per square meter. Most are vegetarian and many prefer fungi. Since they are breaking down organic material and releasing nutrients, their presence is an indicator of soil health. They themselves are eaten by many creatures including soil-dwelling beetles, salamanders and ants.
Antifreeze. Lots of insects, plants and fish (and of course our friend, the wood frog, whom we will be hearing from soon) are known to produce antifreeze proteins which allow them to survive freezing temperatures. The protein binds to the ice as it freezes and prevents ice crystals from forming. There was some excitement in 2005 in the animal antifreeze arena, when scientists at Queen's University in Ontario discovered a new kind of antifreeze protein in snow fleas. Unlike other antifreeze proteins which use threonine-rich sites to bind the ice, the snow flea protein uses glycine-rich sites. The scientists are now trying to find out exactly how this works and to see how humans can benefit. One thought is that the protein could be used to maintain the quality of organs for transplant and prolong the storage time.
Sources. Borror and DeLong's Introduction to the Study of Insects; Fundamentals of Soil Ecology, David C. Coleman & D.A. Crossley Jr.; Royal Society of Chemistry at www.rsc.org for the antifreeze discovery.
Submissions for the Biodiversity Corner are encouraged from everyone. Send a photo, a note about a sighting or the whole column to Kay Fairweather at firstname.lastname@example.org.
© 2007 The Carlisle Mosquito