HEDGEHOG or URCHIN, a mammal of the order Insecti vora (q.v.), remarkable for its armature of spines and short tail. The upper jaw is longer than the lower, the snout long and flexible, and the claws long but weak. The animal is about loin. long, the lower surface covered with hairs of the ordinary char acter. Its eyes are small. The brain is remarkable for its low development. The hedgehog has the power of rolling itself up into a ball, from which the spines stand out in every direction; these are sharp, hard, and elastic, and form an efficient defence. The moment it is touched, or even hears the report of a gun, it rolls itself up by the action of four muscles beneath the skin, while the same contraction effects the erection of the spines.
Though insectivorous, the hedgehog will devour mice, frogs, and toads, as well as plants and fruits. It also eats snakes, and its fondness for eggs has provoked the enmity of game-preservers; and there is no doubt it occasionally attacks leverets and game chicks. It does not emerge from its retreat during daylight, unless urged by hunger or by the necessities of its young. During winter it passes into a state of hibernation (q.v.), rolled up in a nest of dry leaves. In July or August the female brings forth four to eight young ; at birth the spines, which in the adult are black in the middle, are white and soft, but soon harden, attain ing their full size in the succeeding spring.
The hedgehog, known scientifi cally as Erinaceus europaeus, is the type of the family. Erinacei dae, and extends over nearly the whole of Europe. The genus is represented by about a score of species, ranging over Europe, Asia, except the Malay countries, and Africa, being also found at 6,000 to 8,000 ft. above sea-level.