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 the Monotremata order and are the only living mammals that lay eggs. Their diet consists of ants and termites, but they are not closely related to the true anteaters of the Americas. Echidnas live in Australia and New Guinea.