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By Evelyn Ojo
Geographic Range
The geographic range of Ornithorhynchus anatinus is restricted to the wetter regions of eastern Australia and Tasmania. (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
Biogeographic Regions:
australian 
(native ).
Habitat
(3280 ft)
(16.4 ft)
Duck-billed platypuses inhabit rivers, lagoons, and streams (Pasitschniak-Artsand Marinelli, 1998). They prefer areas with steep banks that contain roots, overhanging vegetation, reeds, and logs (Grant and Temple-Smith, 1998). The rivers and streams are usually less than 5 meters in depth (Grant and Temple-Smith, 1998). There have been records of them living in aquatic habitats at elevations above 1000 meters (Grant and Temple-Smith, 1998). (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
These animals are found in the following types of habitat:
temperate ; tropical ; terrestrial ; freshwater .
Terrestrial Biomes:
mountains .
Aquatic Biomes:
lakes and ponds; rivers and streams.
Other:
riparian .
Physical Description
(1.76 to 5.5 lbs; avg. 3.34 lbs)
(15.35 to 23.62 in; avg. 18.31 in)
Duck-billed platypuses are one of three species of monotremes. These species are unique among mammals in that they retain the ancestral characteristic of egg laying. They have a cloaca through which eggs are laid and both liquid and solid waste is eliminated. Duck-billed platypuses are stream-lined and elongated, they have fur ranging from medium brown to dark brown on the dorsal side and brown to silver-gray on the ventral side. They have bills that closely resemble those of ducks, and flat and broad tails resembling those of beavers (Grant and Temple-Smith, 1998). Two nostrils are located on top of their bills and their eyes and ears are on either side of their heads. They have short limbs, naked soles, webbed forefeet and partially-webbed hind feet. Each foot contains five digits each consisting of a broad nail for the forefeet and sharp claws for the hind feet. Males are generally larger than females, and have two venom glands attached to spurs on their hind legs. Females have mammary glands but no nipples. The young have milk teeth while the adults have grinding plates. The young are smaller than adults in size. There is a significant reduction in body fat after winter for both young and adults (Pasitschniak-Arts and Marinelli, 1998). (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
Some key physical features:
endothermic ; homoiothermic; bilateral symmetry ; venomous .
Sexual dimorphism: male larger, ornamentation .
Reproduction
Duck-billed platypuses probably breed once each year.
Duck-billed platypuses breed in late winter or autumn.
Male duck-billed platypuses initiate most mating interactions but successful mating relies entirely on the willingness of females. Mating is seasonal and varies with population. Male and female platypuses touch as they swim past each other. The male grabs the tail of the female with his bill and if the female is unwilling, she will try to escape by swimming through logs and other obstacles until she is set free. However, if she is willing, she will stay near the male and will allow him to grab her tail again if he dropped it. The male then curls his body around the female, his tail underneath her to one side of her tail. Then he moves forward and bites the hair on her shoulder with his bill. Other details of the mating patterns of platypuses are mainly unknown due to their secretive, aquatic nature. There is a higher proportion of spur wounds in males than females, which may be explained by aggressive encounters between males during mating season. (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
Mating systems:
polygynous .
Duck-billed platypuses are one of the three mammal species that lay eggs. There is little available information on breeding, estimated gestation periods are 27 days and incubation periods are 10 days. Lactation lasts three to four months. Most juvenile females do not begin to breed until they are four years old (Grant and Temple-Smith, 1998). (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; oviparous .
Female duck-billed platypuses build burrows in which to protect and nurse their young. During the incubation period, the female platypus will incubate eggs by pressing the egg to her belly with her tail. The incubation period usually lasts for 6 to 10 days. Duck-billed platypuses generally lay two to three eggs. ("Duck-billed Platypus", 2008; Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
Parental investment:
altricial ; pre-fertilization (provisioning, protecting: female); pre-hatching/birth (provisioning: female, protecting: female); pre-weaning/fledging (provisioning: female, protecting: female).
Lifespan/Longevity
There is little information on the longevity of duck-billed platypuses. They can live up to 12 years in the wild.
Behavior
Duck-billed platypuses are solitary, especially males. If the territories of males overlap, they change their foraging time to avoid each other. (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
Home Range
Home range size varies depending on the area, ranging from 0.37-7.0 km. Duck-billed platypuses that forage in streams typically have larger home ranges than those that forage in ponds (Pasitschniak-Arts and Marinelli, 1998). (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
Key behaviors:
fossorial ; natatorial ; diurnal ; nocturnal ; motile ; sedentary ; solitary ; territorial .
Communication and Perception
Duck-billed platypuses make some sounds, but their role in communication hasn't been defined yet (Pasitschniak-Arts and Marinelli, 1998). (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
Other communication keywords:
vibrations .
Food Habits
Duck-billed platypuses eat primarily aquatic invertebrates in streams and lakes (Grant and Tempple-Smith, 1998). They also eat shrimp, fish eggs, and small fish (Pasitschniak-Arts and Marinelli, 1998). (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
Primary Diet:
carnivore (eats non-insect arthropods, molluscivore ).
Animal Foods:
fish; eggs; mollusks; aquatic or marine worms; aquatic crustaceans.
Foraging Behaviors:
stores or caches food .
Predation
- foxes (Vulpes vulpes)
- dogs (Canis lupus familiaris)
- dingos (Canis lupus dingo)
- large snakes (Serpentes)
- birds of prey (Falconiformes)
- feral cats (Felis silvestris)
- eels (Anguilliformes)
- humans (Homo sapiens)
Predators of duck-billed platypuses include foxes, humans, and dogs (Grant and Temple-Smith, 1998). Others are snakes, birds of prey, feral cats, and large eels (Pasitschniak-Arts and Marinelli, 1998).
Ecosystem Roles
There is little information about how duck-billed platypuses affect their ecosystem. However, especially by foraging on aquatic invertebrates, they play an integral role in the food webs of the streams, rivers, and billabongs in which they are found. (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
Key ways these animals impact their ecosystem:
parasite .
- protozoans (Protozoa)
- cestode (Cestoda)
- trematodes (Trematoda)
- nematodes (Nematoda)
- fleas (Siphonaptera)
- mites (Acari)
- ticks (Parasitiformes)
Economic Importance for Humans: Negative
Duck-billed platypuses eat trout (Salmonidae), which are considered a food source for humans. However, trout streams are not privately-owned in Australia so the effect of platypus predation on trouts is neither widely noticed nor regulated. They can harm humans with their venomous spurs if provoked (Grant and Temple-Smith, 1998). (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
Ways that these animals might be a problem for humans:
injures humans (venomous ).
Economic Importance for Humans: Positive
Duck-billed platypus skins were harvested by fur traders to make hats, slippers, and rugs. Harvesting was ended by a law passed in 1912 that protected platypuses from being hunted (Grant and Temple-Smith, 1998). (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
Ways that people benefit from these animals:
body parts are source of valuable material.
Conservation Status
IUCN Red List: [link]:
Lower Risk - Least Concern.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
Duck-billed platypuses are currently protected by the Australian government (Pasitschniak-Arts and Marinelli, 1998). Populations are considered healthy and they are not listed as a species of concern on global conservation lists. (Grant and Temple-Smith, 1998; Pasitschniak-Arts and Marinelli, 1998)
For More Information
Find Ornithorhynchus anatinus information at
Contributors
Tanya Dewey (editor), Animal Diversity Web, University of Michigan Museum of Zoology.
Evelyn Ojo (author), University of Maryland, Baltimore County. Kevin Omland (editor, instructor), University of Maryland, Baltimore County.
