Sloths are slow-moving mammals that spend most of their lives in trees. They cling to the trunks or hang upside down from the branches using their very long, sharp, and strong claws that they use to hold on to tree branches. The claws are also their only natural defense against predators. Sloths can extend their tongues 10 to 12 inches out of their mouths. They are related to armadillos and anteaters.