We are leading a project aiming to reintroduce platypus to the River Torrens/Karrawirra Pari. Here’s all you need to know about these unique egg-laying, bill bearing and otter-like furry creatures.

Platypus swimming
Platypus swimming. Credit: Slow motion Gli

The platypus (Ornithorhynchus anatinus) is an iconic Australian animal, and is part of an exclusive group of mammals (echidnas are the only others in this group) known as monotremes, because unlike other mammals, they lay eggs.

So what else do you need to know about these distinctive creatures? Discover where platypus live, what they eat, their breeding habits and how our rewilding project could see these animals return to the River Torrens/Karrawirra Pari soon.

Platypus head

But first… what do platypus look like?

Platypus have reddish to brown dense, waterproof fur, sometimes described as otter-like. What you might not know is they actually have 2 layers of this fur, and this helps them keep warm. They trap a layer of air next to their skin which helps them float and swim.

They have short, webbed limbs, a distinctive duck-like bill, grooves near their eyes which act as ear holes, and a broad and flat tail.

This combination of features makes them quite unique, and funnily when they were first seen by scientists in Europe, many people questioned whether the animal was even real, or if it was just a hoax!

Platypus are up to 60 cm long and weigh around 1.5 kg.

Where do platypus live?

The unique features of platypus, like their waterproof fur and sharp claws for digging into river banks, makes them well-suited to a semi-aquatic lifestyle – meaning they spend time both in and around water.

Platypus live in freshwater, from tropical rainforests in sunny Queensland to higher altitude rivers and streams in Tasmania, and even the Australian Alps! Here in SA, wild platypus are only found on Kangaroo Island, after being introduced there in the 1920s.

Platypus can feed in both slow moving and rapid parts of streams and rivers, and have shown a preference for foraging in coarse surfaces like gravel, dirt and stones, where their favourite foods hide in all the nooks and crevices.

The ideal platypus habitat needs a mixture of coarse and rocky surfaces as well as submerged logs, twigs and roots for them to forage in, and suitable banks so they can burrow.

Their burrows are where they spend a lot of time (when they are not eating). Platypuses make 2 types of burrows. A camping burrow, with an entrance only just big enough to fit into so that excess water is squeezed out of their fur as they enter their home and a nesting burrow, which females build to be big enough for their young.

What do platypus eat?

Platypuses eat a variety of macroinvertebrates (water bugs), or insects, snails, worms and crayfish.

They eat by pushing their flat bills along the bottom of rivers and streams and use electroreception (it sounds like a superpower, but basically they let out little pulses of electricity and get feedback on what is around them from little electrical signals from their prey) to find food.

Platypus can stay underwater collecting food and storing them in their cheeks for around 2 minutes. They will then rest at the surface of the water to chew their food, grinding it between the broad plates of their bills. They eat a lot of food, spending between 10 and 12 hours of the day foraging!

Two Platypus before mating
Two platypus before mating. Credit: Slow motion Gli

When do platypus breed?

Breeding goes from winter to spring.

A female platypus decides when breeding will occur, resulting in a male grasping her tail and swimming in a tight circle with her, and you can notice breeding behaviours like rolling sideways and diving together.

A pregnant female platypus will build a longer burrow to house her and her eggs. She spends a few days collecting nesting material like wet sticks and leaves to keep her eggs moist. She’ll lay 1-3 eggs usually within 20 days. She keeps them warm by holding them with her tail pressed against her belly.

How does a platypus care for their young?

Baby platypuses (known as puggles) hatch around 11 days after eggs are laid. They will suckle milk from the female platypus for around 3 to 4 months, until they are old enough to leave the burrow.

Uniquely, this doesn’t happen through a nipple like with most mammals, but instead the milk is secreted directly onto the platypus’ belly, where the puggles suck the milk up.

The puggles start off their life as little as a jellybean, but after the 3 to 4 months in the burrow, they are ready forage and make it on their own.

Male Platypus spurs
Male platypus have venomous spurs on their hind legs. Credit: Slow motion Gli

Are platypus dangerous to humans?

Not really. Male platypus can be venomous during breeding season, but the poison isn’t lethal to humans.

They have a hollow spur on each of their hind legs, and during breeding season, it fills from a venomous gland.

It is thought this is to fight off rival males during the breeding season. The male platypus will wrap its hind legs around its target, and then drive the spur into its flesh.

What are some of the threats to platypus?

Predation by foxes, birds of prey and dogs are known threats.

A significant additional threat since the 1990s has been the use of opera house nets in recreational fishing. These nets have had a significant impact on many air-breathing aquatic animals (including platypus, but also turtles and rakali). Thankfully, a recent change means these nets have been banned in South Australia since July 1.

Could there be platypus in the River Torrens/Karrawirra Pari?

We are leading a project aiming to reintroduce platypus to the River Torrens/Karrawirra Pari soon. Platypus were recorded in the river up until the late 1880s but have since been a missing part of the system.

We recently released the findings of an independent scoping study, which investigated the suitability of the river for platypus. The study found a number of positive signs for the future of platypus in the River Torrens, including a high level of macroinvertebrates (platypus food), low levels of litter-based pollution, improved water quality, and suitable habitats for platypus.

Now, we are working on targeted revegetation works and a detailed translocation plan to reintroduce platypus to the River Torrens/Karrawirra Pari soon.

Podcast ep 3
Listen now to ep 3 of our podcast with platypus expert Geoff Williams

Learn more about our platypus rewilding project.

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