Linné's two-toed sloth

Whether they are sleeping, eating, mating, or giving birth, sloths carry out most of their activities hanging upside-down from tree branches. To accommodate their topsy-turvy lifestyle, the internal placement of organs like the heart, liver, and spleen is different from what is usually seen in mammals. Even their hair grows in the opposite direction, curving from stomach to back, probably so that rainwater can flow away from their bodies. Each strand of hair has a groove where algae collects. This gives the sloths an overall greenish hue that camouflages them from predators.