Are animals horns, claws, toenails and hooves made of the same substance?
That depends. Mammalian claws, toenails, hair and hooves are made of alpha keratin. Bird feathers and claws are made of beta keratin. Reptilian claws and scales are also made of beta keratin, but it is a different type than the keratin found in bird feathers. The horns of rhinos are entirely made of alpha keratin, with no bony core. The horns of cattle, sheep and goats have a bony core with an outside cover of alpha keratin. The antlers of deer are not true horns, and it is made of bone with a velvet covering on the outside. When the antler grows to full size, the velvet falls off and the bone dies. Deer shed their antlers later. True horns are not shed. The narwhal’s “horn” is actually its incisor tooth, which not made of keratin.
