Mammals

Only two monotreme types, the platypus (Ornithorhynchus anatinus, family Ornithorhynchidae) and the echidnas, or spiny anteaters (Tachyglossus aculeatus and Zaglossus bruijni, family Tachyglossidae), are known. The earliest monotreme fossils known come from the Australian Pleistocene (2,000,000 or more years ago), and they are essentially the same as the living forms, which range in body length from about 30 to 80 centimetres (12 to 32 inches) and weigh from about one to 10 kilograms (two to 22 pounds).

The platypus, found in eastern Australia from north Queensland to Tasmania, is one of the most remarkable of all mammals. It has a ducklike "bill," webbed feet, and a flattened beaver-like tail. When the first stuffed specimens reached England around the end of the 18th century, they were thought to be fakes, made by sticking together bits of different animals.

The echidnas also rank high among the world's most interesting mammals and are readily kept in captivity for physiological studies. Superficially, they are quite unlike the platypus. They are recognized by their sharp-pointed spines and tubelike noses. Tachyglossus is found throughout Australia, including Tasmania, and part of New Guinea. Zaglossus has an extensive distribution in New Guinea.

Neither the platypus nor the echidnas are readily seen by the casual visitor, but they may be fairly common in some areas. Platypuses are not kept in zoos outside Australia.

The monotremes do not appear to be carriers of diseases harmful to man. Both monotreme types are now wholly protected by law in Australia.

© 1995 Encyclopaedia Britannica, Inc.
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