Hairy Frogs: Meet the Frog That Breaks Its Own Bones to Create Claws

Written by Hailey Pruett
Updated: November 4, 2022
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Hairy frogs sound like something out of a horror movie, but in reality, their unique adaptations are far more fascinating than scary! From its bizarre bony claws and the brutal process in which it forces it to pierce through its own skin to the strange “hairy” protrusions covering much of its body, the hairy frog, also known as the “wolverine frog” or “horror frog,” is perhaps one of the most unusual and visually striking animals in the world.

Let’s take an in-depth look at the hairy frog, its incredible defense mechanisms, and what we can learn from their unconventional way of life.

What Are Hairy Frogs?

The hairy frog’s common name comes from the males’ dermal papillae on their sides and legs.

©Emőke Dénes / Creative Commons – License

Native to the warm, humid forests of Cameroon and a handful of surrounding African countries, the hairy frog is the lone species within its genus, Trichobatrachus. The carnivorous frogs went undiscovered for quite some time (until 1900!) due to their reclusive nature.

Though the females of the species look like typical frogs, the males have dermal papillae, or hair-like protrusions, on their sides and back legs. These papillae only appear during the frogs’ breeding season. While their purpose was initially a mystery, researchers now believe the papillae have arteries in them to assist with breathing!

Hairy frogs spend most of their lives on land, but they lay their eggs in shallow water. The males of the species notably display a small amount of parental care to their young. Using their “hairs” to help absorb more oxygen, the males stay in the water and protect the eggs until they hatch.

Aside from the males’ fuzzy-looking bodies, hairy frogs are known for their retractable claws, which they use for defense. Instead of being made of keratin, like most animals’ claws, the hairy frog’s are made of actual bone! The frog forces these bony projections through their own skin when necessary for defense. Later, they regenerate the torn skin and slowly retract the claws, covering them with a protective layer of tissue until the hairy frog needs them again. And it’s no wonder they are called wolverine frogs!

Currently, the species is not classified endangered, though habitat loss is sadly beginning to diminish their numbers. They are also commonly eaten by local tribal peoples, who typically hunt them with spears.

Do Hairy Frogs Have Claws?

The hairy frog’s “claws” are actually made of bone

©Gustavocarra / Creative Commons – License

Interestingly, hairy frogs have claws. Their “claws” are actually made of bone rather than keratin like the true claws of most other animals. These sharp protrusions are typically covered in skin and attached to small, bony nodules by thick pieces of collagen.

When the frog needs them for protection, they will force the bony “claws” to pierce through their skin, breaking away from the bony nodules that usually anchor them. Later, the pierced and damaged tissue will regenerate, covering the sharp, bony tips in a new layer of skin. The collagen and bony nodule gradually reform to protect the claws until the frog needs to use them again.

We currently understand that the hairy frog’s claws are mostly used for self-defense. However, other theories suggest the frogs also use them to grab onto rocks and other surfaces for climbing and swimming. This could also be helpful for the male frogs while they protect their eggs.

While many species of amphibians have regenerative qualities, the hairy frog’s regenerative abilities are truly unique. Every time they use their bony claw-like protrusions, they must re-puncture their own toe pads. As the claws retract, the frog’s body gets to work repairing the damaged tissue. This creates a new protective skin sheath for the claws, and the collagen strands reattach…until the frog feels threatened again, and the whole process starts over (just like the comic hero Wolverine, remember?).

Needless to say, these claws are an unusual defense mechanism amongst frogs. The hairy frog is able to catch its predators by surprise, as its claws normally stay tucked away beneath the skin on its toes. Most species rely on camouflage, poisonous skin, or simply their long, flexible legs to jump and swim away from predators.

Do Hairy Frogs Actually Have “Hair?”

The “hairs” on the hairy frog’s legs contain blood vessels used to take in oxygen

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Hairy frogs have got their name because it seems they have hair on their skin. However, the hairy frog’s “hairs” are not true hairs at all but rather dermal papillae. Only the males of the species possess them temporarily during the frogs’ breeding season. These papillae have thin arteries inside, which many researchers believe assist the frogs with taking in oxygen, particularly while the males protect the females’ eggs near the surface of the water.

Just like the hairy frog’s claws (which are actually bones), its hair (which is not made of hair at all) is a bit more complex than it seems at first glance. For many years, the male frog’s “hairs” were a mystery to animal biologists and researchers. 

Instead of functioning like hair, the dermal papillae have thin arteries in them. The male frogs use these blood vessels to absorb more oxygen while they protect the females’ eggs. The arteries function a lot like most tadpoles’ gills. This is quite useful for the males, as they must stay near the eggs in the water for many days at a time until they hatch.

What Do Hairy Frogs Eat?

Hairy Frogs

Hairy frogs feed on insects, slugs and snails.

©Emőke Dénes / Creative Commons – License

Hairy frogs are carnivores who primarily eat insects and mollusks, like slugs and snails. Though they use their claws for self-defense, hairy frogs typically don’t use them to hunt their prey. This is likely because their prey are small and weak enough that the frog doesn’t deem it necessary to go through the bone-breaking, wolverine-like, frog process of unsheathing its claws every time it needs to eat.

Just like most carnivorous frogs, hairy frogs mostly eat small insects and arthropods. The frogs’ tadpoles are notably self-sufficient almost immediately after hatching. This is mostly thanks to the tadpoles’ strong, muscular bodies and rows of sharp teeth

As the frogs mature, the way they hunt and eat is fairly uneventful and similar to most other frogs. More specifically, they ambush their prey and eat just about anything they can get into their mouths. Rather than using their claws to hunt their prey, they can rely on their teeth and bite force alone.

The photo featured at the top of this post is © Emőke Dénes / Creative Commons – License / Original

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About the Author

Hailey "Lex" Pruett is a nonbinary writer at A-Z Animals primarily covering reptiles and amphibians. They have over five years of professional content writing experience. Additionally, they grew up on a hobby farm and have volunteered at animal shelters to gain further experience in animal care. A longtime resident of Knoxville, Tennessee, Hailey has owned and cared extensively for a wide variety of animals in their lifetime, including cats, dogs, lizards, turtles, frogs and toads, fish, chickens, ducks, horses, llamas, rabbits, goats, and more!

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