The back and sides of the body are covered with thorns, and the head, tail and ventral surfaces are covered with hair; the mouth is pointed and long, and the tail is short; both the front and rear feet have 5 toes, which are plantar, and a few species have 4 toes on the front feet; there are 36 to 44 teeth, all with sharp teeth.Pointed, suitable for eating insects; when frightened, the thorns on the body stand upright and roll up into a thorn ball, and the head and four legs are invisible.