Monotremes: Order Monotremata

The monotremes can be distinguished from the placnetal mammals (or eutherian mammals) on the way they reproduce.  Monotremes are the only  mammals are oviparous (egg layers).

There are only a few types of monotremes: the Duck-billed platypus, the short-billed echidna and the long-billed echidna.

The name Monotremata means "one opening", and refers to the cloaca, a common opening for the fecal, urinary and reproductive tracts.