animals adapted to living in deserts. Desert fauna is diverse but poorer in species than the fauna of well-watered areas as, for example, forest fauna. The faunas of different desert biotopes vary in composition and richness. Richest in species is the fauna of stabilized sands, especially where there are trees and shrubs. The fewest species are found on bare shifting sands and in vast stony deserts.
The conditions for life in the desert are very harsh: a lack of water, the dryness of the air, intense solar radiation, and very low winter temperatures with little or no snow cover. Consequently, deserts are inhabited chiefly by specialized forms with morphological-physiological and behavioral adaptations. The ability to move rapidly is characteristic of desert animals, enabling them to travel long distances in search of water (watering places are far apart) and food (the grass cover is sparse) and to protect themselves against pursuit by predators in the absence of shelters. To conceal themselves from their enemies and avoid the harsh climatic conditions, some animals have adaptations for digging in sand. They include brushes consisting of long supple hairs, little spines and bristles on the legs to scrape away and throw back sand, and incisors and sharp claws on the front paws (rodents). These animals build underground shelters (burrows), often very large, deep, and complex (great gerbil), or they can quickly bury themselves in loose sand (toad-headed agamids, some insects). Among animals that depend on swiftness for survival are the ungulates. Many desert reptiles, both lizards and snakes, can also move rapidly.
Desert animals have a “desert” coloration of yellow, light brown, and gray tones which makes many of them hard to detect. In summer many desert species are active only at night. Some animals become dormant. Among ground squirrels, for example, summer dormancy begins during the hottest period and merges with winter hibernation. The onset of summer dormancy is associated with the drying up of vegetation and insufficient moisture. The shortage of moisture, particularly drinking water, is a basic problem for desert species. Some animals drink regularly and copiously, traveling long distances to find water (sandgrouses) or migrating closer to water sources during the dry season (ungulates). Others drink rarely or irregularly or not at all, obtaining moisture from food. Metabolic water is a major factor in the water balance of many desert species, which therefore build up large fat deposits. The most specialized of the desert animals are the psammophiles.
The conditions for life in the deserts on the various continents are very similar and have resulted in the development of similar biological types of desert animals belonging to different taxonomic groups (convergence). The “jerboa” type is represented in Europe, Asia, and North Africa by the family Dipodidae, in North America by kangaroo rats, and in Africa by springhares (Pedetes capensis) and elephant shrews (Macroscelididae). Desert fauna includes a comparatively large number of species of mammals (chiefly rodents and ungulates), reptiles (especially agamids and varanids), insects (particularly Diptera, Hymenoptera, and Orthoptera), and arachnids (solpugids and scorpions).
REFERENCESGeptner, V. G. Obshchaia zoogeografiia. Moscow-Leningrad, 1936.
Bobrinskii, N. A., and N. A. Gladkov. Geografiia zhivotnykh, 2nd ed. Moscow, 1961.
V. G. GEPTNER