a comical appearance. Two-toed sloths hang from tree branches, suspended by their huge, hook-like claws. The clinging behaviour is a reflex action, and sloths are found still hanging from trees after they die. The sloth spends almost its entire life, including eating, sleeping, mating, and giving birth, hanging upside down from tree branches. Usually, sloths are found right side up when they descend to the ground to defecate, which they usually do about once every three to eight days. They will also ground themselves to urinate, change trees if they wish, or mate, as well as give birth. While terrestrial locomotion is usually thought to involve the sloth lying on the ground and pulling themselves forward, they have actually been seen walking on their palms and soles. Sloths descend about once every eight days to defecate on the ground. The reason and mechanism behind this behavior have long been debated among scientists. There are at least five hypotheses: 1) fertilize trees when feces are deposited at the base of the tree; 2) cover feces and avoid predation; 3) chemical communication between individuals; 4) pick up trace nutrients in their claws, that are then ingested and 5) favor a mutualistic relationship with populations of fur moths. More recently, a new hypothesis has emerged, which presents evidence against the previous ones and proposes that all current sloths are descendants from species that defecated on the ground, and there simply has not been enough selective pressure to abandon this behavior, since cases of predation during defecation are actually very rare. Sloths have many predators, including the jaguars, ocelots, harpy eagles, margays, and anacondas. If threatened, sloths can defend themselves by slashing out at a predator with their huge claws or biting with their sharp cheek teeth. However, a sloth's main defense is to avoid being attacked in the first place. The two-toed sloth can survive wounds that would be fatal to another mammal its size. The sloth's slow, deliberate movements and algae-covered fur make them difficult for predators to spot from a distance. Their treetop homes are also out of reach for many larger predators. Their long, coarse fur also protects them from sun and rain. Their fur, unlike other mammals, flows from belly to top, not top to belly, allowing rainwater to slide off the fur while the animal is hanging upside down. Hoffmann's two-toed sloth inhabits a range of different trees