MorphologyRead full entry
Allactaga tetradactyla is a small kangaroo-shaped animal with long, slender ears that are approximately the same length as their head. Their head and body length ranges from 90-263 mm and their tail length is approximately 142-308 mm. They have large eyes (a typical trait of nocturnal animals). Their hind legs are four times greater than their front legs, as is true of other jerboas. The 3 main footbones in their hind legs are fused into a single "cannon bone," which provides mechanical advantage for jumping (MacDonald, 1984 ). A. tetradactyla is the only species within the Jerboas that has four toes (hence the common name 4-toed Jerboa). It has only one small lateral digit (vs. the other species where there are either 2 outer toes or none at all). The sole of the hind foot has a tuft of stiff hairs, which acts as a steering mechanism while they leap. This hair also helps them to kick sand backwards while burrowing. There is another tuft of hair located on the opening of the ear that aids in keeping wind-blown sand from entering (Nowak, 1991). They have padded feet to help absorb and cushion from the shock of landing. A long tail balances the animal while resting and jumping, and it also acts as a brake during running (Hanney, 1975). The vertebrae of the neck region are short and expanded, and several are fused together. Jerboas have inflated bullae and the cheek teeth are rooted, high crowned and cuspidate (Nowak, 1991). They have velvety hair that is usually the same color as the sand they burrow in (sandy or greyish) and a white underbelly.
Average mass: 52 g.
Other Physical Features: endothermic ; bilateral symmetry