Duckbill Platypus, or Duck Mole, an egg-laying mammal of Australia. Platypuses and echidnas, collectively called monotremes, are unique among mammals in that they lay eggs. In this and certain other respects monotremes are similar to reptiles.
The platypus's body, about 20 inches (50 cm) long and covered with grayish-brown fur, resembles that of a muskrat. The tail is broad and short like a beaver's. The platypus has acute vision and hearing. Its ears are located in furrows behind the eyes. The animal's jaws extend in a duck-like bill covered with smooth, black, sensitive, leathery skin. The feet are webbed and the membranes of the front feet fold back into the palms to expose sharp digging claws. For defense, the male's spiny spurs on its hind feet give off a poisonous secretion much like the venom of a snake's fangs.
The platypus is amphibious; it is an excellent digger, swimmer, and diver. When it submerges, folds of skin cover the eyes and ears. Sensory cells on the surface of the bill detect weak electrical currents in the water, allowing the platypus to locate preyfrogs, worms, insect larvae, and shellfish. Platypuses dig burrows along the shores of ponds or sluggish streams; the entrance to a burrow is usually above water.
Platypuses mate in the water. The female then collects leaves and grass and retreats into her burrow. She plugs the entrance with mud and builds a nest from the leaves and grass. She lays small white eggs (typically two) that have leathery shells like the eggs of reptiles.
The female curls her body around the eggs during incubation. During the incubation period, which lasts about 10 days, the female rarely leaves the nest; she does not eat until after the eggs hatch. The female has glands that discharge milk between folds of skin, where the young lap up the milk. The young emerge from the burrow when they are about four months old.
Platypuses are difficult to observe. When startled, they dive underwater or retreat into their burrows. Adults occasionally make a low growling sound. Platypuses were formerly hunted for their pelts, which were used to make rugs, but they are now protected by law.
The platypus is Ornithorhynchus anatinus of the family Ornithorhynchidae.