The Horror Frog, a frog that breaks its own bones to create claws for fighting. Perhaps that sounds like something made up to you, but it is in fact a real animal. There are actually multiple real species possessing such abilities. The two most well known are: the Hairy Frog, which lives in Central Africa and intentionally breaks the bones of its toes to create “claws” when threatened, and the recently discovered Otton Frog, which lives in Southern Japan and possesses a retractable “spike” hidden within a false thumb.

With regards to the hairy frog, there is some disagreement amongst researchers about whether or not the frogs use it for fighting/competition or whether it has other purposes. The Otton frog though, without a doubt, uses its retractable spike/claw for fighting.





So now, lets get into the awesome details…

The hairy frog is about 11 cm long, and possesses, as its name implies, features on its body that resemble hair. This “hair” is thought to essentially function like gills. The frog, as previously mentioned, possesses retractable “claws” made of bone which can be projected through the skin, “apparently by intentionally breaking the bones of the toe”.

There is a “small bony nodule nestled in the tissue just beyond the frog’s fingertip. When sheathed, each claw is anchored to the nodule with tough strands of collagen, but, when the frog is grabbed or attacked, the frog breaks the nodule connection and forces its sharpened bones through the skin.” Researchers have theorized that this is most likely a defense behavior. It is not currently known exactly how they are retracted, but it seems to be a passive process. The damaged tissue then regenerates over it after it has completely retracted.

That’s certainly a frog very fitting of being labeled “the horror frog”. Can you imagine if every time people got in fights they did that…

The Otton frog though, is quite a bit different, and perhaps more deserving of the label: Horror Frog; as it does indeed break its own bones to make claws.

The frog was discovered only very recently, on the Southern Japanese Amami Islands. Most frogs possess only four digits, but the Otton frog possesses a false fifth-digit which conceals a retractable spike which it uses for fighting. It’s apparently used not just for fighting though, but also during mating.

The Amami Islands are apparently a very competitive place for frogs to live, as the heavily scarred bodies of the males show, which is possibly what led to the emergence of such a “strange” weapon. It’s worth noting that the claws are used primarily for grappling though, not stabbing or cutting type motions.

It’s also worth noting that the Otton frog is currently endangered and well on its way to extinction. This is almost entirely because of habitat loss caused by deforestation and expanding human settlements.