Subzero survival in terrestrial animals

Abstract

Although maximum diversity amongst terrestrial arthropods (insects, spiders, scorpions mites, ticks) occurs in the tropics, and relatively low numbers of species occur in high altitude, high arctic and antarctic regions, the few coldtolerant species are often important ecologically in cold areas. Anyone who has encountered the high biomass of biting flies in marshy areas of Canada, Iceland, Norway and Finland can certainly vouch for their prominence! Because such arthropods (particularly insects and mites) are characteristic of inland ecosystems (e.g. tundra, muskeg), far from the moderating influence of the sea, they may encounter very low temperatures (− 30 to −60°C) in winter. Because the ground and vegetation freezes it is often impossible for these animals to avoid exposure to the full rigours of ambient air temperatures. Some arthropods maintain activity at subzero temperatures; Dalenius (1965) reported that the mite Maudheimia wilsoni, which tolerates temperatures as low as − 30°C, was capable of locomotion and reproduction at temperatures below — 0°C. However, the majority of temperate and high latitude arthropods spend the cold winter in diapause — a state of arrested development or dormancy.