Phascolarctos cinereus                Herbivore         Nocturnal          Status: Least concern

The arboreal koala likely descended from a wombat-like animal at a time when the northern half of Australia was covered with rainforest. It is thought that the koala’s diet constricted to eucalyptus leaves when that tree began its domination of the continent as it cooled. Its brain size has been shrinking, likely due to this nutrient-poor diet.

Koalas have opposable thumbs and fingerprints so similar to a human’s; it can be difficult to distinguish them even under a microscope. Koalas occupy the same niche as the sloths of South America, and like those creatures, they are active only a few hours a day.

Photo courtesy of Jan Zawadzki.