Claws For Concern?

New research, published in the journal Biology Letters, has brought to light a frog with a difference. Phil Leftwich gets on the case and finds out about the X-frog.

Everyone remembers the X-men, comic books or films it doesn’t matter. Wolverine is in both, he’s short, hairy and he springs out a nasty set of claws when he’s mad, which is often. In short “He’s the best at what he does and what he does isn’t very nice, bub!”

Now dispel that picture of Hugh Jackman from your mind, and instead picture this, Harvard biologists have found all of this in a frog. That’s right; they’ve found a small, hairy, clawed, frog!

The hairy frog: Chuck Norris-like in hairiness and deadly ability.
Click image to enlarge.

Trichobatrachus robustus, commonly known as the hairy frog, purposefully breaks its own bones, which then puncture its skin in order to produce claws. The Harvard biologists that discovered it think that this extreme behaviour is probably a defense mechanism.

The claws are found only on the hind legs, and when the frog is resting they sit within a mass of connective tissue. The claw is connected by a piece of collagen to the bone that forms the tip of the frog’s toe. When the frog is threatened, it contracts a muscle at the other end of the claw, breaking it away from the collagen and it cuts down and out of the toe pad.

This method of releasing the claw is not only gruesome, leaving a traumatic wound with torn skin, but unique amongst vertebrates. Another original feature is the claw itself, which while resembling that of a cat’s, is not covered in the layer of keratin found on all other claws, instead it is merely pure bone.

On the inside and on the outside, it's grim.
Click image to enlarge

The retraction method remains a mystery as well, with only dead specimens studied so far, but may simply return passively to its resting position. Amphibians are well known for their remarkable healing properties, so it’s entirely possible that the epidermis, dermis and all the connective tissue may regenerate completely, leaving no sign that these claws exist.

Gory, vicious and an unwelcome surprise for any unsuspecting predators, truly this is nasty nature at its most gruesomely fascinating!

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