Bradypus tridactylus is a strange animal. It has almost no tail or external ears, and its head is slightly rounded with a blunt nose. The body is covered with long and course hair. Very small green algae sometimes live mutualistically in the pits of the hair, which gives the sloth an overall greenish appearance that camouflouges it in the forest canopy.
Male sloths have a bright yellow or orange patch on the back.
The females have two mammae in the chest region. The three-toed sloth is armed with long, compressed, arched, hollowed claws, of which the middle claw is the largest. Bradypus tridactylus grows to a length of between 1.5 and 2.5 ft. The limbs are long and weak, with anterior extremities that are nearly double the length of the posterior. The three-toed sloth is herbivorous.