The house mouse (Mus musculus) is a small mammal of the order Rodentia. characteristically having a pointed snout, large rounded ears, and a long and hairy tail. House mice have an adult body length of 7.5–10 cm and a tail length of 5–10 cm. The weight is typically 40–45 g. In the wild they vary in color from grey and light brown to black. They have short hair and some, but not all, sub-species have a light belly.