Koalas are Australia's national emblem. They are not bears, but belong to a genus all of their own.

Meaning of scientific name
Phaskolos is Greek for a bag or pouch, and arktos means bear = bear with a pouch. Cinereus is Latin for ash-coloured.

Life span
18 years.

Statistics
Head-body length: male: 78cm, female: 72cm. Weight: male: 11.8kg, female: 7.9kg. Individuals in the north are smaller (males average 6.8kg and females 5.1kg).

Physical description
Koalas have grey fur, with a white chin, chest and inner forelimbs. Their ears are fringed with white fur. They have strong, sharp claws for climbing. The female's pouch opens to the rear and includes two teats. Koalas are virtually tailless and have a large leathery nose. On the forepaw the first and second digits oppose the other three, which enables the koala to grip branches as it climbs.

Distribution
They inhabit eastern Australia but have been introduced to western Australia and nearby islands.

Habitat
Koalas live in Eucalypt forest.

Diet
They mainly feed on the leaves of 30 different species of Eucalyptus, but also a small amount of foliage from acacias, leptospermum and melaleuca. They eat about 500g of fresh leaf daily.

Eucalypts are not the best choice of food for a herbivore - they are low in nutrients, high in indigestible lignin and cellulose and laced wih toxins. Koalas, however, are able to detoxify the poisons in their liver and excrete them. They cope with the lack of energy by sleeping up to 20 hours a day. They also have the longest caecum (intestinal pouch) of all mammals, reaching 7m in length, to aid digestion.

They obtain all the water they need from their food - in fact 'koala' is an aboriginal word meaning 'no drink'.

Behaviour
Koalas spend about 80 per cent of their time sleeping. Less than 10 per cent is spent feeding and the rest is just spent sitting. They are excellent climbers, and are slow walkers when on the ground.

Koalas are solitary with fixed home ranges. These vary in size according to the habitat and its available resources. The ranges of dominant males may overlap with up to 9 females, plus subordinate males.

Koalas have no sweat glands and they cool themselves by licking their arms.

Reproduction
Females become sexually mature at 21-24 months. One young is born in Nov-March after a gestation period of 35 days. Koalas weigh less than 0.5g when they are born. The baby climbs from the urogenital opening to the pouch and attaches on to a teat. It is weaned after 5 months, whereupon it feeds on partially-digested vegetation excreted by its mother's anus.

It leaves the pouch after 7 months and clings to the female's back. The young becomes independent after a year, but tend to live near their mother for several months.

Dominant males do most of the matings, and fights sometimes occur to establish rank.

Conservation status
Koalas are listed by the IUCN Red List 2000 as Lower Risk/near threatened. The are common in their favoured habitat, particularly in the south of their range. The first European settlers hunted koalas in their thousands for their pelts. In 1924, more than 2 million skins were exported. Nowadays they are more common, but forest clearance and disease (Chlamydia psittaci - which can make them sterile) is still a threat.

Voice
The males bellow constantly during the breeding season to frighten off other males and to attract females.

Notes
Koalas have a very small brain - less than 0.2 per cent of their body weight. This is likely to be an adaptation to their low energy diet.

The leaves the koala eats contain strong smelling oils that seem to act as a bug repellent, keeping the animal free from parasites. They also make the koala smell like very strong cough sweets