There are only five species of monotremes:
* The echidnas: There are four species of echidnas, all of which are found in Australia and New Guinea.
* The platypus: The platypus is the only member of its family and is found in eastern Australia.
These animals are unique because they have several features of reptiles, including laying eggs, but they are also considered mammals because they have fur, produce milk to nourish their young, and are warm-blooded.