A sloth and its fur ecosystem

In many sloths, hair grows from a part along the belly toward the back—opposite the usual direction in most mammals and suited to an upside-down lifestyle; this arrangement also helps rain run off. Algae can live in grooves along the hairs, while fungi, bacteria, and small arthropods also inhabit the fur. Algae give the coat a greenish tint that may aid camouflage. The interactions in this “ecosystem” are complex and not all are well understood.