There's so much to know about the Platypus, it's too long to go into here. I'll just give you some of the main facts and if you're interested, check out the links or do a search yourself. They are AMAZING!
Platypuses, like echidnas, are monotremes which are mammals that lay eggs.
They are well-suited to their semi-aquatic life. Their streamline body and a broad, flat tail are covered with dense waterproof fur, providing excellent thermal insulation. They self-propel through the water by using their front, short, webbed limbs, and the partially-webbed hind feet act as rudders. The tail is used for storage of fat reserves and the strong claws on its feet for burrowing and moving on land. Males possess a horny spur on their ankles, which is connected to a venom gland in the upper leg, making the Platypus one of the few venomous mammals. This spur is used when fighting other males in mating season!
Platypus can be found (though less and less) from the tropical rainforests of far northern Queensland to cold, high altitudes of Tasmania and the Australian Alps. The species was once found in the Adelaide Hills and Mount Lofty Ranges of South Australia. Now it is extinct from that state, except for the introduced population on Kangaroo Island.
When not foraging, the Platypus spends most of the time in its burrow in the bank of the river, creek or a pond. They are active all year round, but mostly during twilight and in the night. During day, they stay in their burrow.
They feed mainly on aquatic invertebrates. The average foraging periods last for 10-12 hours per day. A Platypus closes its eyes, ears and nostrils when foraging underwater and its primary sense organ is the bill, equipped with receptors sensitive to pressure, and with electro-receptors. It stays underwater between 30-140 seconds, collecting the invertebrates from the river bottom and storing them in its cheek-pouches. It then chews the food using its horny, grinding plates, while it floats and rests on the water surface.
There's lots of videos and other info you can look up. Here's just three links you might like.
This is an engaging interview with a British scientist who has made it a bit of a mission to discover all he can about our Platy: https://www.abc.net.au/listen/programs/conversations/jack-ashby-is-an-expert-on-platypus/106636826
Here's a short video of David Attenborough (seeing it's his birthday) explaining the story of the impact the Platypus had on the British scientific establishment when it was first found: https://www.youtube.com/watch?v=dBRVueeH0mg
And here's a longer video of the latest Platy discoveries: https://www.youtube.com/watch?v=1ABN5dLK3L4
