Members of the family Erinaceidae (order Insectivora), which includes 7 genera and 19 species of medium- to large-size animals generally characterized by spines on their back and sides. This family, however, is subdivided into two subfamilies: the spiny hedgehog group which includes the European hedgehog (Erinaceus europaeus); and the hairy hedgehogs or gymnuras, long-tailed species which lack spines. The typical spiny hedgehog has well-developed eyes and a rudimentary to moderately long tail. In most species, there are five toes on each foot, although in some species these are reduced to four on the hindfeet. The spines can be erected by strong muscles, and serve as a protection for the naked or hairy belly, head, and limbs when the animal rolls itself into a ball.