According to biologists at Harvard University, some African frogs can morph their toes into claws by puncturing their own skin with sharp bones. The bones are sharp enough to wound predators and protect the frogs from danger, but obviously it’s using sparingly since it requires the bone to pierce the skin on their feet. These “claws” are nothing like the claws of a cat which retract into a special spot, the frogs suffer a wound each time they use the claws!

This claw-like structure is no conventional claw, though: It is pure bone, free of the keratin sheath that normally surrounds vertebrate claws. And unlike a claw that retracts into a specialized structure in an animal’s foot, as in cats, the site where the frogs’ foot bones emerge appears to be covered with ordinary skin.

The frogs are widely roasted and eaten in Cameroon, where hunters — evidently well aware of the risk of injury — go to great lengths to avoid handling them when alive.

“Cameroonian hunters will use long spears or machetes to avoid touching these frogs,” Blackburn says. “Some have even reported shooting the frogs.”

“We suspect, since the frog does suffer a fairly traumatic wound, that they probably use these claws infrequently, and only when threatened,” Blackburn says.

Okay, so the frogs aren’t much like Wolverine from the X-Men, except for the fact that they have retracting claws they can use to wound others. Pretty sweet!

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