Each hind toe of Trichobatrachus robustus contains a sharp bony claw anchored at rest to a small nodule of bone. A muscle connects the claw to the pelvis. Contraction pulls the claw down, snapping it free of the nodule so the point breaks through the toe pad. The result is a functional weapon on an animal that otherwise has none.
The claws are not sheathed and are not retracted in the way a cat's are. Whether they withdraw at all when the muscle relaxes, and how the wound heals afterwards, has not been well documented, though the tissue is presumed to regenerate. Hunters in Cameroon are reported to use long spears and machetes rather than grabbing the frog by hand.
The hairs are a separate feature. They are not hair but dermal papillae grown by breeding males, densely supplied with blood vessels, and are generally interpreted as increasing surface area for oxygen uptake while the male remains with the eggs in a stream for long periods. Only breeding males grow them, and they are shed afterwards.