We’ve talked about some weird animals on EarthDate, but the platypus may be the strangest.

They’re famous for having a duckbill and a beaver tail. But that’s just the start of it.

Platypuses are monotremes, one of just three mammals—all in Australia—that lay eggs. But they also produce milk to nurse their young once hatched.

And they’re one of the few venomous mammals. Males have sharp spurs on their back legs that can inject poison potent enough to send a human to the hospital.

They spend much of their time underwater at night, making over a thousand short dives in a 24-hour period, hunting worms, crayfish, and water insects.

They close their eyes, ears, and nostrils underwater, so they rely on their bill to navigate. It has two types of electroreceptors, using direct current to avoid large objects when swimming and alternating current to detect the muscle activity of their prey.

They then zero in, using sensitive pressure receptors that can detect tiny movements in the water—less than the thickness of a human hair.

Their hips are splayed like a reptile’s. Their fur fluoresces under UV light like some marsupials. Their eyeballs are wrapped in cartilage like a bird but shaped like those of other water mammals. And their gene code shows ancestry from each of these animal groups!

Of course, all this weirdness is in the eye, or the bill, of the beholder. To a platypus, we furless bipeds may be the truly odd ducks.