The koala (Phascolarctos cinereus) is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae. It is classified in the suborder Vombatiformes within the order Diprotodontia, and its closest living relatives are the wombats. The koala is found in coastal areas of the continent's eastern and southern regions, inhabiting Queensland, New South Wales, Victoria and South Australia. It is easily recognisable by its stout, tailless body, round, fluffy ears and large, spoon-shaped nose. It is popularly known as the koala bear because of its bear-like appearance. The koala has a body length of 60–85 cm (24–33 in) and weighs 4–15 kg (9–33 lb). Pelage colour ranges from silver grey to chocolate brown. Koalas from the northern populations are typically smaller and lighter in colour than their counterparts in the more southern populations. It is possible that these variations are separate subspecies, but this is disputed.
Koalas typically inhabit open Eucalyptus woodlands, and the leaves of these trees make up most of their diet. Because this eucalypt diet provides them with only low nutrition and energy, koalas are largely sedentary and sleep for up to 20 hours a day. They are asocial animals, and bonding only exists between mothers and dependent offspring. Adult males communicate with loud bellows that intimidate rivals and may also attract mates. Males mark their presence with secretions from their chest glands. Being marsupials, koalas give birth to underdeveloped young that crawl into their mothers' pouches, where they stay for the first six to seven months of their life. These young koalas are known as joeys, and are fully weaned at around a year.