It’s very rare for frogs to have five toes on their front feet. They usually only have four.
The Otton frog, from Japan, however, is fairly unique in this respect because it not only has a thumb, it has a thumb that will end you. Because this “thumb” is actually a freaking spike, made out of bone.
It also uses it to pin females for mating. Yes, nature has given us the stabby rapist frog.
Thanks, nature. You shouldn’t have. No, we mean you should not have done this.
So, why did the stabby rapist frog come into existence?
That’s a bit up in the air, actually. The Otton frog is endangered, possibly because of that whole “stabbing the females you’re mating with” thing, and only lives on Japan’s Amami Islands. The bone claw they have is fairly serious business: Researchers get stabbed a lot, and study subject turn out to be covered with scars from fights.
How did this happen? Sex. Frog sex is generally “a big pile of frogs spraying their bodily fluids everywhere.” Seriously. It’s a frog orgy. It’s gross. Hilarious, but gross. The Otton frog, for contrast, breeds in pairs. They’re also prone to attacking each other in the middle of having sex, so the claw serves a purpose of making it harder to be pulled away and stabbing the guy trying to pull you off the female you’re having sex with.
That said: GAH! STABBY RAPIST FROG!