Platypuses
The platypus, an extraordinary mammal found in Eastern Australia, Tasmania, and Kangaroo Island, is one of only five existing species of monotremes, which are unique for laying eggs instead of giving birth to live young. This fascinating creature features a leathery bill, webbed feet, and dense fur, adaptations that suit its aquatic lifestyle in streams, rivers, and lakes. The platypus primarily forages at dusk and relies on its highly sensitive bill equipped with electrosensors to detect prey in murky waters, consuming a diet mostly of crustaceans, worms, and aquatic insects.
Males possess venomous spurs on their hind ankles, a rare trait among mammals, which they use defensively during mating season. After mating, females lay two to three eggs and nurse their young with milk expressed through openings in their abdomen, as they lack nipples. Platypuses typically live for around ten years in the wild and have significant cultural importance in Australia, often symbolizing the region and appearing on currency. Although they are currently classified as "near threatened" due to habitat loss and other environmental pressures, they are not considered endangered, highlighting the need for ongoing conservation efforts to protect this unique species.
Platypuses
Platypus Facts
Classification:
- Kingdom: Animalia
- Subkingdom: Bilateria
- Phylum: Chordata
- Subphylum: Vertebra
- Class: Mammalia
- Subclass: Prototheria
- Order: Monotremata
- Family: Ornithorhynchidae
- Genus and species: Ornithorhynchus anatinus
- Geographical location: Eastern Australia, Tasmania, Kangaroo Island in southern Australia
- Habitat: Streams, rivers, and some lakes; must have permanent water and banks suitable for burrows
- Gestational period: Seven to fourteen days
- Life span: Ten or more years in the wild; seventeen years and longer in captivity
- Special anatomy: Rubbery bill equipped with electrosensors used to detect prey; webbed feet; females have slits in abdominal walls from which milk expresses during lactation; males have spurs on rear feet used primarily to inject venom into rivals during mating season; reproductive and excretory tracts have one common opening to the exterior of the body
When the first platypus pelt arrived at London’s Natural History Museum in the late 1790s, it was thought to be a hoax made from bits of other animals sewn together. This unusual animal has a leathery bill, webbed feet, and fur, and it is one of only five extant species of monotremes, mammals distinguished by the fact that they lay eggs (the other four are all echidnas, or spiny anteaters). The platypus's body length is about eighteen inches, and its broad, flat tail is about seven inches long, though fossil records suggest that ancestral species were significantly larger. The reclusive platypus (sometimes referred to as the duck-billed platypus) spends most of its time in streams, rivers, and some lakes, foraging for food in the evening and sleeping during the day in burrows dug into the river banks.
Platypus Life
The unusual anatomical features of the platypus provide perfect adaptations for its life in water. The webbed feet are efficient paddles for swimming through the water. Claws on the feet help the platypus to dig burrows. Dense, waterproof fur covers the entire body except the feet and bill. The eyes and ear holes of the animal lie in folds that close when the animal is submerged, and the nostrils are located toward the end of the beak and also close underwater. The bill is highly sensitive to touch, and is equipped with electrosensors that detect weak electrical fields produced by prey. Thus, the platypus can locate and capture prey in murky river bottoms without relying on vision, hearing, or smell.
Bottom-dwelling invertebrates, especially crustaceans, worms, aquatic insects, and insect larvae, compose the majority of the platypus diet. Behind the bill are located two internal cheek pouches containing horny ridges that substitute for teeth, which are lost early in the life of the platypus. The pouches are used to store food while it is being chewed and sorted by the animal. Taking in small pieces of gravel while feeding also helps "chew" the food.
A male platypus has a spur on each rear ankle that is connected to a venom gland in the thigh. The spur is used against attackers, but also against competing males during the mating season. The venom is not fatal to humans, but can cause a great deal of pain—some reports even suggest that it causes an increased pain sensitivity, or hyperalgesia, for an extended amount of time. This feature makes the platypus one of very few mammals that are venomous. They are known to growl and make other sounds when threatened.
From Egg to Adult
Courtship and mating occur in the water. After initial approaches by the female, the male chases and grasps her by the tail and inseminates her. After mating, a female will lay two to three eggs and incubate them in a special nesting burrow, which may extend one hundred feet away from the water. The female blocks the entry to the nesting burrow with soil plugs to protect the eggs and young from predators and flooding. She removes and replaces the plug each time she leaves to forage for food. When the eggs hatch, in seven to fourteen days, the young are about one inch long and totally dependent on the mother. Platypuses do not have nipples, but milk is produced in the mammary glands and expressed through openings in the abdominal wall. The young suck the milk directly from the fur. At about five months of age, the young emerge from the nesting burrow and begin learning to search for prey themselves. A typical platypus in the wild will live about ten years.
The platypus is found only in Eastern Australia and Tasmania, and it has become an important symbol in those regions, appearing on Australian currency and postage stamps and as a mascot for the 2000 Olympic Games in Sydney, Australia, for example. Though the platypus was once hunted, including for its fur, it is now protected everywhere it occurs. It is also an important species to scientists in the study of evolution in general and the development of mammals in particular. Though little is known about the total platypus population due to a lack of research and data, they are not considered an endangered species. However, a suspected overall decline led the International Union for Conservation of Nature and Natural Resources (IUCN) to change the platypus' status from "least concern" to "near threatened" in 2014 on its Red List of Threatened Species. Threats include predation by invasive species, loss of freshwater habitat, and climate change. Another concern is a fungal infection reported in Tasmanian populations that causes skin ulcers and can lead to death.
Principal Terms
dorsal: at or near the back
electroreceptors: sensors in the bill of the platypus that detect the weak electric field given off by animals; the electroreceptors help the platypus locate prey in murky water
metazoa: organisms which are multicellular
monotreme: mammals that lay eggs and have a single, common, outer body opening for the excretory and reproductive systems; includes platypuses and echidnas
notochord: longitudinal, flexible rod located between the gut and nerve cord
Bibliography
Brown, Malcolm W. "If a Platypus Had a Dream, What Would It Mean?" The Science Times Book of Mammals. Nicholas Wade, ed. Lyons Press, 1999.
Divljan, Anja. "Platypus." Australian Museum, 28 Apr. 2022, australian.museum/learn/animals/mammals/platypus. Accessed 8 July 2024.
Lanese, Nicoletta. "Platypus Facts." LiveScience, 18 Feb. 2022, www.livescience.com/27572-platypus.html. Accessed 8 July 2024.
Macdonald, David, ed. The Encyclopedia of Mammals. 2nd ed. Facts on File, 1995.
"Platypus." National Geographic, www.nationalgeographic.com/animals/mammals/facts/platypus. Accessed 8 July 2024.
Whitfield, Philip, ed. The Simon and Schuster Encyclopedia of Animals. Simon & Schuster, 1998.