also called DUCKBILL (species Ornithorhynchus anatinus), a small, semiaquatic, oviparous mammal, the sole member of the family Ornithorhynchidae, order Monotremata. It lives in lakes and streams of eastern Australia and Tasmania. The platypus is notable in having a broad, flat, rubbery snout and in laying eggs. It has a squat body, short splayed legs, webbed feet, and a flat beaverlike tail. Its total length is about 60 cm (24 inches). The dense soft fur varies from yellowish to dark brown. The male of the species has a poison spur on each hindfoot for sexual combat; the poison is intensely painful to humans.

The platypus' sensitive snout has been shown by researchers to contain electroreceptors, which enable it to detect the electrical field produced by the moving muscles of its prey. The platypus finds its food chiefly in underwater mud, and it consumes daily nearly its own weight in crustaceans, fishes, frogs, molluscs, tadpoles, and earthworms. It burrows above the waterline; the long twisting passage dug by the female contains a nest in which she lays one, two, or three sticky soft-skinned eggs. Incubation takes about 10 to 12 days. The young platypus has elongated lips (the incipient bill) for sucking milk, exuded from the nippleless mammae. Weaning occurs four months after hatching.

Because of their enormous appetites, platypuses are difficult to maintain in captivity; one is known to have survived in a zoo, however, for 17 years. Their natural enemies are large fishes and, perhaps, snakes. Platypuses formerly were trapped for their pelts but are now protected by law.

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