Ah, the platypus. One of nature’s weirdest mammals, if I do say so myself. These small, roughly cat-sized mammals have a lot going on in their body: a duck-bill, a beaver-tail, and otter-feet. They honestly look like someone just taped a bunch of different animals together.
And the first European scientists thought so too. Native to Australia, the platypus is so weird that early scientists didn’t think it was real. Which, honestly, that’s a fair assessment — imagine your reaction if you had no idea platypuses existed, and someone sent you a picture. I bet you’d have some doubts as well!
The first Western scientist to study a platypus, George Shaw, thought for sure someone was playing a trick on him when the pelt showed up on his doorstep. He thought perhaps someone had sewn a duck’s bill onto an otter or mole body before sending it to him, since the weird pelt “naturally excites the idea of some deceptive preparation by artificial means.” Shaw even cut the platypus skin in an attempt to find the stitches holding it together. Of course, he didn’t find any.
You heard it here first, folks! Platypuses are real animals, not Frankenstein-like creations of different animal pelts sewn together. And I bet they’re even weirder than you realized.
There is only one species of platypus, the duck-billed platypus (Ornithorhynchus anatinus). Platypuses and the four existing species of echidnas make up the mammalian group of monotremes. The other two mammalian groups are placentals (those with a placenta, like us) and marsupials (koalas, kangaroos). With only 5 species of monotremes, they’re a pretty exclusive group!
But what exactly makes a monotreme, a monotreme? You might be able to guess if you remember your Greek. Monotreme means “single opening.” And that’s all monotremes have. Just like birds and reptiles, monotremes have a cloaca. This is a one-stop shop for their urinary, defecatory, and reproductive systems. Males do have a penis, but the only substance that comes out of it is semen.
Platypuses lay eggs. Which would make sense if they were birds or reptiles. But platypuses are mammals, and mammals aren’t really supposed to lay eggs. So the platypus (and other monotremes) are the sole egg-laying mammals.
Platypus eggs are leathery, like reptile eggs, and slightly rounder than bird eggs. Platypuses eggs develop in their mother for around 28 days before being incubated externally for about 10 days. For comparison, chicken eggs develop in their mother for just one day and are externally incubated for 21 days. When her eggs are laid, the platypus mother will curl around them in her underground burrow to keep them warm.
But is also a mammal
Even though they lay eggs, platypuses are mammals at the end of the day. And one key characteristic of mammals is that they raise their young on milk. Platypuses are no different – they feed their babies milk.
What is different is how platypuses and other monotremes give their young milk. You see, platypuses don’t have nipples. Instead, milk comes from their mammary glands through holes in their skin. Platypuses basically sweat out their milk. It then pools in their body grooves, where the babies can lap it up and suck the milk off their mother’s fur. Yum.
But milk time doesn’t last forever
But of course, platypus babies aren’t babies forever, and they eventually grow up and eat solid food. In the case of the carnivorous platypus, this food takes the form of small invertebrates like worms, insect larvae, and freshwater shrimp.
A large part of a platypus’ day is looking for food – 12 hours on average. This is because they need to eat about 20% of their body weight daily. The good news is that they’re great swimmers, so it’s relatively easy for them to catch their prey. Once prey is caught, the platypus stores it in their cheek-pouches until they return to the surface.
Platypuses eat their food not with teeth, but with pads called ceratodontes. That’s right: platypuses don’t have teeth. Well, technically the babies have a few teeth. But those fall out pretty early on in life.
Back to ceratodontes – these are heavily keratinized pads used to grind food. Keratinized means that they’re made of keratin, the same protein that makes up our hair and fingernails. These ceratodontes are plates (4 total – two on top, two on bottom) that form from the epithelium of inside the mouth.
Platypuses are also venomous…
They are in fact one of the few venomous mammals! Male platypuses have a spur on each hind foot that is connected to a venom gland. Because the venom glands only seem to be activated during the mating season, it’s possible that males use these spurs to compete for mates.
Female platypuses are not venomous – while they have spur buds on their ankles, they never develop into full spurs. Females also don’t have functional venom-producing glands.
Fortunately, platypus venom doesn’t kill humans (although it can kill smaller animals like dogs). However, I still don’t recommend getting stabbed by a male platypus. It is apparently quite painful – platypus poisoning “results in excruciating pain accompanied by massive swelling.” Some report being in such horrible pain after platypus stabbing that they are debilitated for weeks.
(Remember: if it bites you and you die, it’s venomous; if you bite it and you die, it’s poisonous).
And have electrolocation…
Monotremes and one species of dolphin are the only mammals we know of that locate their prey via electric fields in living things. Basically, when your muscles contract, they give off small electric fields. Platypuses use these fields to track their prey.
Platypuses have extremely sensitive electroreception, and they hunt using the electroreceptors in their bill exclusively. When they dive, platypuses close their eyes, ears, and nose. As they dig through the bottom of the stream looking for food, the electroreceptors on their bill pick up those tiny electric currents from muscle contractions. Since only living things have muscles that contract, the platypus just needs to follow the electricity in order to find their prey.
And glow under an ultraviolet light…
Some mammals, like opossums and flying squirrels, glow under an ultraviolet (UV) light. These mammals are either nocturnal or crepuscular (active during twilight), and, given that platypuses are also nocturnal / crepuscular mammals, scientists in 2020 decided to see if they glowed as well.
And their hunch was right! After placing the brown pelt of a museum specimen under a UV light, scientists found the fur was glowing a blue-green. We still don’t know why they glow (or why other mammals do, for that matter), but one hypothesis is that it may be helpful for seeing each other in low-light conditions.
In a weird twist of fate, platypuses happen to glow a shade of blue pretty close to the color of Perry the Platypus in the 2007 cartoon “Phineas and Ferb.”
That’s the platypus for you.
They are so weird and I love it. I hope you do too.