One Funky Frog

Biologists have described a bizarre, hairy frog, which in a gruesome process, actively breaks its own bones to produce cat-like extendable claws. According to a report in New Scientist, the frog, known as Trichobatrachus robustus, has been described by David Blackburn and colleagues at Harvard University’s Museum of Comparative Zoology.

The researchers believe that the gruesome behaviour of this frog is a defence mechanism, also observed in nine of the 11 frogs belonging to the Astylosternus genus, most of which live in Cameroon.

T. robustus actively breaks its own bones to produce clawsthat puncture their way out of the frog’s toe pads, probably when it is threatened. This indicates that this gruesome behaviour might serve as a defence mechanism for the frog.

The claws of T. robustus, found on the hind feet only, are nestled inside a mass of connective tissue. A chunk of collagen forms a bond between the claw’s sharp point and a small piece of bone at the tip of the frog’s toe. The other end of the claw is connected to a muscle.
Blackburn and his colleagues believe that when the animal is attacked, it contracts this muscle, which pulls the claw downwards. The sharp point then breaks away from the bony tip and cuts through the toe pad, emerging on the underside.

The end result may look like a cat’s claw, but the breaking and cutting mechanism is very different and unique among vertebrates. Also unique is the fact that the claw is just bone and does not have an outer coating of keratin like other claws do.

via Arbroath