Snow flea

Snow flea ( Isotomidae Gen. sp.)

As Snow Fleas several types are called wingless Sechsfüßer from the class of springtails, been snowed upon. Surfaces by their dark body color that make hopping locomotion and often by mass occurrences attention to themselves Frequent winter active forms on snow in Europe, for example Ceratophysella sigillata, Desoria hiemalis, Desoria violacea, Hypogastrura socialis and HIDE Opus westerlundi, frequent Schneecollembolen North America, for example Hypogastrura harveyi and H. nivicola. At high altitudes is partly the same and partly related species found on snow surfaces, which are then referred to as " glacier fleas " (for BV westerlundi ).

Typically live " snow fleas " in humid forests, preferably under conifers. From Desoria hiemalis is known that the species occurs in a summer and a winter form, which can be distinguished morphologically. The Sommermorphe lives in the leaf litter, the Wintermorphe migrates temperatures above -3 ° C on the snow surface. Sunlight and high humidity favor the diurnal activity in winter. The animals move directed over the snow, use the polarized light and landmarks around for orientation and thereby reach top speeds of up to 120 inches per minute. However, most species move more slowly on snow, the average speeds are 0.5 to 3 meters per hour. From their main food, coccoid algae that Collembola win high molecular weight " Antifreeze " proteins that enhance their supercooling ability and thus their antifreeze. This glycine - rich proteins bind to newly forming ice crystals and thus delay the formation of a Eisglumerates. With the exception of C. sigillata take winter active Collembola during the winter no food on, but live of reserve substances they have built up in the fall in the body.

In frost-free days from the end of January, countless animals (see photos) collect in depressions in the snow. 1000-10000 animals per square meter are in C. sigillata and H. socialis not uncommon; Desoria and HIDE Opus hike mostly in densities of less than one animal per m². In parts of its range, such as in subalpine coniferous forests, the occurrence of this species are limited during the summer months on gatherings moist needle litter. The walks are probably the discovery of new habitats, as the food resources are depleted rapidly by mass propagation in such small-scale habitats. For hiking over longer distances the equally smooth as wet snow surface is far better suited than any forest floor for Collembola. Obstacles can easily be overcome and snow-free habitats are quickly reached, in which the propagation can be started early. For the kind Ceratophysella sigillata was proven that it uses late winter and spring for propagation, food intake and reproduction, during the summer and autumn are spent in dormancy. In addition to temperature, moisture, and sunlight air pressure fluctuations are assumed to be controlling factors of migration. At a temperature of less than -3 ° C. D. searches hiemalis protection of the snow surface or in the ground, with less than -7 ° C, the type falling into hibernation. The cold tolerance of winter active Collembola varies depending on the type -2 to -44 ° C.