Echidnas, sometimes known as spiny anteaters, belong to the family Tachyglossidae in the monotreme order of egg-laying mammals. The four extant species, together with the platypus, are the only surviving members of that order and are the only extant mammals that lay eggs. Although their diet consists largely of ants and termites, they are no more closely related to the true anteaters of the Americas than to any other placental mammal. They live in Australia and New Guinea. The echidnas are named after a monster in ancient Greek mythology.