The koala is about 60 to 85 cm (24 to 33 inches) long and weighs up to 14 kg (31 pounds) in the southern part of its range (Victoria) but only about half that in subtropical Queensland to the north. Virtually tailless, the body is stout and gray, with a pale yellow or cream-coloured chest and mottling on the rump. The broad face has a wide, rounded, leathery nose, small yellow eyes, and big fluffy ears. The feet are strong and clawed; the two inner digits of the front feet and the innermost digit of the hind feet are opposable for grasping. Owing to the animal’s superficial resemblance to a small bear, the koala is sometimes called, albeit erroneously, the koala bear.
The koala feeds very selectively on the leaves of certain eucalyptus trees. Generally solitary, individuals move within a home range of more than a dozen trees, one of which is favoured over the others. If koalas become too numerous in a restricted area, they defoliate preferred food trees and, unable to subsist on even closely related species, decline rapidly. To aid in digesting as much as 1.3 kg (3 pounds) of leaves daily, the koala has an intestinal pouch (cecum) about 2 metres (7 feet) long, where symbiotic bacteria degrade the tannins and other toxic and complex substances abundant in eucalyptus. This diet is relatively poor in nutrients and provides the koala little spare energy, so the animal spends long hours simply sitting or sleeping in tree forks, exposed to the elements but insulated by thick fur. Although placid most of the time, koalas produce loud, hollow grunts.
Koala babies are called joeys. A newborn joey looks just like a pink jellybean! It’s about 2 centimetres long, has no fur and its eyes and ears are not yet fully formed. Koala joeys are born without fur, and with their eyes and ears not yet fully developed. This joey is about 2 to 3 months old.
Amazingly, the tiny joey makes its way from the birth canal to the pouch without any help from its mother, climbing up through the fur on her abdomen to the pouch opening. Once inside, it attaches itself to one of the two milk teats which swells to fill its mouth.