Why male platypuses have venomous spurs

HostWe all know the platypus is a bit of a weird one. It has a bill like a duck and a tail like a beaver, and the whole thing feels like a bit of a prank. But there's one part of this animal that's less like a joke and more like a secret weapon. What's actually going on with those spurs on their back legs?

GuestWell, if you look at the back ankles of a male platypus, you'll find these sharp, hollow spikes. They look a bit like the spur on a rooster, but they're connected to a sack of venom in the leg. It's one of the strangest things in nature because we just don't see many furred animals that can poison you. Most venomous creatures are snakes or spiders or fish. But here is this egg-laying creature that can deliver a kick that will make a grown man cry for days. The weirdest part is that the females are born with these spurs too, but theirs just drop off as they grow up. Only the males keep them, and they only really load them with venom during the few months of the year when they're looking for a mate.

HostSo they don't use these to protect themselves from things that want to eat them?

GuestNot usually, no. I mean, if a dog or a person grabs them, they'll use them, and it hurts like nothing else. But that's not what the spurs are for. We know this because the venom glands only grow big and start pumping out poison during the breeding season. If it was for self-defense, they would need that protection all year round. Predators don't take a week off just because it's not mating season. This is a weapon built for one specific job, which is fighting other male platypuses. When two males want the same patch of river or the same mate, they wrestle. They wrap around each other and try to drive those spurs into the other guy’s back or tail. It's a way of saying this spot is mine, and I'm willing to make you regret being here.

HostThat seems like a lot of work for a fight over a spot in the river. Why go straight to a chemical attack instead of just growling?

GuestIt's all about the stakes. In the wild, if you can knock your rival out of the game for the whole season, you win. The venom isn't meant to kill. If you kill your rival, that's a lot of energy spent, and it might even be risky for you. But if you give him a dose of pain that's so bad he can't even swim or hunt for a week, you have basically removed him from the dating pool. The venom has dozens of different bits in it that attack the body in different ways. Some bits break down blood vessels, and others go straight for the nerves. It creates a kind of pain that we don't really have a good way to stop.

HostI mean, we have some pretty strong medicine. Are you saying a tiny platypus makes something that a hospital can’t handle?

GuestThat's often the case. People who have been stung by a platypus say the pain is so intense it can make them faint. And here is the catch, morphine doesn't really touch it. Most of our drugs work by blocking certain spots in the brain or the spine, but platypus venom seems to flip a switch on the pain nerves themselves and just locks it in the on position. It makes those nerves way too touchy to everything. Even a light touch or a small change in temperature feels like a fresh burn. That pain can last for weeks or even months. Imagine trying to fight for a mate when your whole body feels like it's on fire every time you move. You're going to give up and hide in a hole until the season is over.

HostSo it's a long-term way to stop a rival. But where did they even get this stuff? Did they just happen to find the same recipe as a snake?

GuestIt's a case of nature finding the same answer twice. If you look at the pieces that make up the venom, they're actually very similar to what you find in some snakes or lizards. But the platypus didn't get it from them. They don't share a close ancestor that was venomous. Instead, the platypus took normal proteins that were already in its body, like things that usually help with the body's defenses or help with breaking down food, and over millions of years, those bits changed. They got doubled and tweaked until they became poisonous. It's like taking a kitchen tool and sharpening it into a spear. It shows that there are only so many ways to make a good poison, so nature tends to go back to the same toolkit.

HostIt's wild to think that this creature that looks like a mashup of spare parts has such a high-tech weapon hidden on its ankles.

GuestScientists are even looking at these poisons now to see if the way they lock onto our nerves could help us build better ways to treat people who have to live with constant pain.

HostThose duck bills and beaver tails don't look like a joke anymore now that we know they come with such a sharp set of tools.