How Are Monotremes Classified?

　　There are only three species in the order Monotremata, the monotremes. They are classified in two families, the Tachyglossidae and the Ornithorhynchidae.

　　The Tachyglossidae consist of the two species of echidna, also known as the -spiny anteaters because of the short nosed echidna, which feeds exclusively on ants and termites. The short nosed (or short beaked) echidna Tachyglossus aculeatus is widespread throughout Australia, Tasmania and New Guinea, and occurs in a broad range of habitats. The long nosed (or long-beaked) echidna Zaglossus bruijni is much more limited in its distribution; it is found only in the highlands of New Guinea and possibly on the Indonesian island of Sulawesi.

　　The Ornithorhynchidae consists of one species only: the platypus Ornithorhynchus anatinus of coastal eastern Australia and Tasmania. It is also known as the duckbill or duck-billed platypus. A semi aquatic species, it occurs in fresh water, in rivers, streams and lakes, requiring places where the banks are soft enough for burrowing.