Lizards have claws, not nails. Claws are sharp, curved structures that are found on the toes of lizards and other animals. They are made of keratin, the same protein that makes up hair and nails in humans. Lizards use their claws for a variety of purposes, such as climbing, digging, and catching prey. Some species of lizards also use their claws for self-defense, while others use them to help them move more efficiently over different types of terrain.