The horror frog might be the most bad ass amphibian in the game. Plenty animals are willing to go to great evolutionary lengths to defend themselves – poisonous secretions, butts covered in quills – but few rival the horror frog’s investment in personal security. When threatened, the horror frog actually breaks a bone in its toe, forces the broken end through its own skin, and uses it to stab its foes.

In the each of horror frog’s hind toes are bones that come to sharp points. The points are capped with a small nodule of bone that is attached to the actual sharp end. When the frog is attacked, it breaks the nodule off the end of the pointed bone, effectively unsheathing it for battle. The frog then forces the sharp point through its own skin and tries to shank the hungry predator with it.

While it winds up looking like a cat or lizard claw, the fact that it actually breaks through a layer of skin puts it in a whole other category of vertebrate physiology. It’s also very odd that the projecting material has no special keratin coating as is the case with most animal claws.

The ultimate concealed weapon. (Blackburn)

David Blackburn of Harvard’s Museum of Comparative Zoology led a study on these bizarre frogs. Blackburn and his team only observed dead horror frogs, so it remains unclear how the claws retract back into the toe once the threat has been neutralized (frog-stabbed to death or just scared off). There doesn’t seem to be any one muscle designed for pulling the claw back into position. “Being amphibians, it would not be surprising if some parts of the wound heal and the tissue is regenerated,” Blackburn says.

Victor Creed ain’t got nothing on the horror frog. (Blackburn)

The horror frog is also called the “hairy frog” since the males will grow long hair-like skin and arteries that aid oxygen intake. (Gustavocarra / Creative Commons License)

In Cameroon, these frogs are hunted for food. With males growing to 11 inches long they presumably yield a significant amount of protein, but wrangling these amphibians isn’t as simple as catching a friendly bull frog.  Not wanting to get frog-stabbed, the hunters use long spears and machetes to kill the frogs before they even touch them.

Source: New Scientist