gerbils are a family of rodents. there are about 110 species of gerbils. all gerbils are adapted to arid habitats. at one time, gerbils were known as wild rats. most gerbils are diurnal, some are crepuscular. the gerbil is native to central asia, india, the middle east, and africa. the average length of a gerbil is usually between six and twelve inches, this includes the tail which makes up one half of the total length. the gerbil is also a common household pet.