From top to tail, platypuses (or platypodes) can be 60cm long. Males can weigh 3kg; females 1.7kg.
In colder climates individuals are slightly larger, but they don’t come close to the size of prehistoric platypuses, which were 1m long!
The name Platypus comes from the Greek word for ‘flat-footed’ – they're very awkward on land, walking on their knuckles to protect the webbing of their feet.
Expert swimmers, they use these webbed feet to propel themselves and use their tails to steer through the water. Their dense, silky brown fur is both waterproof and insulating – along with the fat reserves in their tails, their fur allows them to stay warm underwater.
Their ‘duck bill’ is flexible, rubbery and feels like suede. It's often used to dig up food from the riverbed. A Platypus bill is also highly sensitive. Platypuses use electroreceptors on their bills to detect electrical signals given off by prey as it moves.
In other words, with its eyes, ears and nostrils closed, a Platypus can use electroreception to detect movement underwater.
This explains its characteristic side-to-side head movement while hunting. In this way they hunt for prey underwater for 30 to 140 seconds at a time.
The Platypus is one of very few venomous mammals in the world. The spur on the male’s hind foot is connected to a venom-secreting gland. Recent research suggests that the spur is used in aggressive encounters between rival males.
For humans, the venom is non-fatal, but it can cause swelling, loss of muscle control and severe pain.
It’s little wonder that 19th Century European scientists found it difficult to believe that the Platypus was real, and fancied this half-beaver, half-bird hybrid to be an elaborate hoax.
Today the Platypus is celebrated as one of Australia’s most unusual and unique animals – it's the state animal of New South Wales and proudly represented Australia in the 2000 Olympics…. as a mascot!
Taxonomically, it's the only species in the family Ornithorhynchidae.
Where do Platypus live?
Platypuses are endemic to (only found in) east and south-eastern Australia. They’re found in freshwater creeks and rivers of Queensland, New South Wales, Victoria, Tasmania and South Australia. They can live in many habitats, from tropical rainforest creeks to streams in alpine areas.
Platypuses are not endangered but the International Union for Conservation of Nature has upgraded their status to 'Near Threatened'. Elusive by nature, there’s a lack of reliable data about where and in what numbers they occur. They’re protected by legislation in all of Australia's eastern states.
How do Platypus behave?
Platypuses are mostly nocturnal. During the day they sleep in the chambers at the end of riverbank burrows. At dusk they emerge to search the river bottom for food, sometimes hunting for 10 to 12 hours a night.
They’re completely carnivorous (meat-eating) and mostly eat invertebrates: swimming beetles and waterbugs, insect larvae, tadpoles, worms, snails and shrimp.
They scoop up gravel and dirt along with their prey, store it in their cheek-pouches, and bring it all to the surface to eat.
Like echidnas, platypuses don’t have teeth. Instead, they use a grinding plate to mash the gravel, soil and food slurry, scooped from the riverbed. They can eat an impressive amount of food in a night – up to 20% of their own body weight!
Females breed at 4 years. After burrowing deep into the riverbank, pregnant females lay one or two eggs. Here, curled up in protective chambers, they incubates their eggs between their tail and rump.
Bean-sized babies emerge from the egg after 10 days and are fed milk for about four months.
Platypuses don’t have nipples; instead milk is secreted through pores and licked off the mother’s skin or fur.
By the time the young are weaned off milk they can swim independently. While largely solitary, Platypuses don’t mind sharing their waterbody with other individuals.
They can live to 12 years old in the wild.
Threats to Platypus
Given their dependence on freshwater systems, habitat destruction and waterway pollution threaten this species.
Water extraction, dams and diversions to water flow have a big impact. Water quality and in-stream habitat (such as submerged logs) are critical so degradation of these elements is a threat.
Run-off from pasture (sediments and nutrient load) can degrade Platypus habitat.
Platypuses are eaten by snakes, water rats, birds of prey and occasionally crocodiles. It’s likely that foxes, dingoes and wild dogs kill Platypuses that venture on land. They were once hunted for their fur – pelts are both warm and waterproof.
What Bush Heritage is doing
Sit quietly by the water at our Liffey Valley, ‘Nameless’ Sylvan or Scottsdale reserves and you might spot this shy species. We look after their habitat by maintaining riparian vegetation (which filters run-off into waterways) and in-stream habitat (e.g. fallen logs, deep pools) and by managing stream-bank erosion.
Canoeists paddling through Black Rock Gorge on a mission to control willows along the upper Murrumbidgee River found this ‘stranded’ juvenile Platypus in a sinkhole on the bedrock platform of the falls. Unable to climb out, the little platy was swimming ‘round and round’ in the sinkhole and by the bedraggled looks of it, maybe had been there for a while!
Upon being hauled up, the little platy rested, exhausted in the rescuer’s hands … but to our delight … after about 5 minutes started to preen itself. Twenty minutes later, its fur fluffed up like a mink coat on parade, our platy friend was larking about amongst the rocks near the edge of a nearby pool where it had been placed - oblivious that we were watching!
Black Rock Gorge is a little travelled, pristine and (to say the least) highly scenic section of the upper Murrumbidgee River … part of which forms the Scottsdale Reserve boundary. This part of the river is also the home of several nationally listed threatened fish species.
Bush Heritage at Scottsdale is a key partner of the Upper Murrumbidgee Demonstration Reach (UMDR).
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