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Frog Claws

July 1, 2008

Some African frogs have claws that can rip through flesh.


An amphibian’s bloody defense. I’m Bob Hirshon and this is Science Update.

Pick up the average frog, and it’s unlikely to put up much of a fight. But the hairy frog of central Africa is a different story. Harvard evolutionary biologist David Blackburn learned the hard way.

DAVID BLACKBURN (Harvard University):
I got quite a shock when I picked one up for the first time and had it kick wildly and rake its bony claws into my skin. They can give you a cut deep enough to bleed, sometimes it can be an inch or so long.

He says the frogs’ painful claws are formed from a special bone in each of their toes. When disturbed, powerful muscles pull on this bone, causing it to puncture through the skin of the toe. He thinks the claw may have evolved as a defense against predators and adds that only about a dozen species of frogs from the same family sport the claws. I’m Bob Hirshon, for AAAS, the science society.