The koala is a small bear-like, tree-dwelling, herbivorous marsupial which averages about 9kg (20lb) in weight. Its fur is thick and usually ash grey with a tinge of brown in places.
The koala gets its name from an ancient Aboriginal word meaning "no drink" because it receives over 90% of its hydration from the Eucalyptus leaves (also known as gum leaves) it eats, and only drinks when ill or times when there is not enough moisture in the leaves. ie during droughts etc.
The koala is the only mammal, other than the Greater Glider and Ringtail Possum, which can survive on a diet of eucalyptus leaves.
Climbing trees
When approaching a tree to climb, koalas spring from the ground and catch their front claws in the bark, then bound upwards. Claw marks are usually visible on the trunks of trees regularly used as home trees by koalas.
In the safety of their home trees, koalas assume a wide variety of sitting and sleeping postures, and they will move around the tree during the day and night to catch the sun or the breezes. On hot days it is common to see them with limbs dangling in an effort to keep cool, and during colder times, curled up in a ball to conserve body heat.
When descending a tree, koalas come down bottom first. They regularly descend to the ground to change trees, and it is there that they are most vulnerable to predators such as dogs, foxes and dingoes, and also to the risk of injury or death from cars. They walk with an awkward-looking gait and can also run. Koalas have sometimes been observed swimming, but this is not a regular occurrence.