The koala is an arboreal herbivorous marsupial native to Australia, and is recognised worldwide as a symbol of the country because of its distinctive appearance. It is the only extant representative of the family Phascolarctidae and its closest living relatives are the wombats. 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 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. They have few natural predators and parasites but are threatened by various pathogens, as well as by bushfires and droughts. The biggest threat to their existence is habitat destruction due to agriculture and urbanisation.