African Frogs Break Own Bones to Form Claws

A study of rare African frogs has revealed a form of self-defense hitherto unbeknownst to the scientific world: claws of pure bone that burst through the frogs' skin. And it gets worse. When the frogs are threatened they need to first "actively break" their own bones in order to create these claws.

Don't make me angry...you wouldn't like me when I'm angry.

David Blackburn of Harvard's Museum of Comparative Zoology released his team's findings last week in Biology Letters on the Trichobatrachus robustus, and ten other related species of frog, most of which live in Cameroon.

The frogs' claws differ from other...

creatures' in many ways. The first is that the claws are not coated in keratin, like pretty much all other known claws in the vertebrate world. Most surprising, however, is how the frogs make the claws and from where they burst forth. When put in a compromising situation, the T. robustus appears to flex a muscle which in turn breaks a certain bone into pieces creating a sharp point. The point then pushes through the frogs' own skin, and out of its toe pad.

"Some other frogs have bony spines that project from their wrist, but in those species it appears that the bones grow through the skin rather than pierce it when needed for defense," Blackburn said to New Scientist.

Blackburn has only studied dead specimens of the frogs, but he is speculating that rather than contracting the claws, the frog may regenerate the broken skin around it, like other amphibians in similar situations. The famous Belgian zoologist George Boulenger described the contracting claws of African frogs way back in 1900, but he failed to grasp just how unique this adaptation was.

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