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Duck-Billed Platypus

Ornithorhynchus anatinus [or' nith O rin kuhs an ah' tin uhs]


One of the oddest looking animals on Earth, the duck-billed platypus looks like it was created from parts left over from other animals. It has the streamlined body and short limbs of an otter, a bill like that found on a duck, and the broad, flat tail of a beaver. The forefeet are fully webbed, while the hind feet are only partially webbed. There are five digits per foot, each ending in a broad nail on the forefeet and a sharp claw on the hind feet. Males also have a hollow spur on the ankle of each hind foot that can deliver a venom capable of killing a small dog and causing excruciating pain in an adult human. The animal is 15-1/4 to 23-1/2 inches long and weighs 1-3/4 to 5-1/2 pounds; males are generally larger than females. The three-layered fur ranges from medium to dark brown in color on the dorsal side and from brown to silver-gray on the ventral side.


Like river otters, platypuses are built for swimming, with the heavily webbed front-feet providing propulsion through water, while the hind-feet act more like rudders. Platypuses move a bit more awkwardly on land, but the webbing on their feet retracts to expose individual nails and allows the creatures to run. Platypuses use their nails and feet to construct dirt burrows at the water's edge.

close up of platypus foot showing spur

Distribution and Habitat

Platypuses inhabit rivers, lagoons, and streams in eastern Australia and Tasmania, usually in water less than 16-1/2 feet deep. They prefer areas with steep banks that contain roots, overhanging vegetation, reeds, and logs. They have been found living at elevations up to and over 3,280 feet.

Habits and Behaviors

Platypuses are solitary, especially males, except when mating. If the territories of males overlap, they usually change their foraging times to avoid each other. Platypuses that forage in streams typically have larger home ranges than those that forage in ponds.

Platypuses burrow into banks, creating tunnels that can be 100+ feet long and that have nesting chambers at the end. They spend their days in their burrows, coming out at night to feed.

The platypus swims with its eyes shut. It can swim underwater for 2 minutes before having to surface for air, but can stay underwater (if not active) for up to 10 minutes.


The platypus's bill is soft, flexible, and covered with sensory receptors that can detect electrical and tactile stimuli. It uses its bill to "shovel" aquatic invertebrates, fish eggs, and small fish from the stream or lake bed. The findings are stored in special pouches behind the bill, and are consumed upon returning to the surface. A platypus can consume its own body weight worth of food in one 24-hour period.


Platypuses mate once a year, sometime between June and October, depending on local population. The male initiates most mating interactions, but successful mating relies entirely on the willingness of the female.

After a gestation of about 27 days, the female seals herself inside one of her burrow's chambers to lay 1-3 soft-shelled eggs. She will incubate the eggs by pressing them to her belly with her tail for about 10 days. The platypus is one of only two mammals to lay eggs, the other being the echidna. Platypus infants are the size of lima beans and totally helpless at birth. They lick milk from the mother's mammary gland, which has no nipple and simply oozes milk like sweat, for 3-4 months, at which time they can fend for themselves.

Platypuses reach sexual maturity at about 3-4 years, and can live up to 20 years in the wild.

Scientific Classification

phylum Chordata
subphylum Vertebrata
class Mammalia
order Monotremata
family Ornithorhynchidae
genus & species Ornithorhynchus anatinus


Animal Diversity Web
Australian Fauna
BBC Nature
National Geographic

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The Robinson Library >> Order Monotremata

This page was last updated on September 28, 2018.