Koalas have brownish-grey or silver-grey fur, and a big pink and/or black nose. They have sharp claws which help them to climb. They can hear and smell very well, but they cannot see very well at all.
Koalas are mostly active at night. They live in trees, and they do not like to be on the ground. They mostly eat leaves, bark and fruit of some Eucalyptus trees. Koalas do not drink often, they get most of their water from the leaves they eat.
Koalas live alone most of the time, but they have a social hierarchy with the other koalas who live near.
After a pregnancy of 35 days, the newly born koala is about a quarter of an inch long, and is born with no ears, eyes, or hair. It crawls into its mothers pouch on its own. After 12 months the young koala is old enough that it does not go into its mother's pouch or need milk anymore. The female koala can have another baby then. Young koalas usually leave their mothers when they are 18 months old, but if their mother does not have another baby they sometimes stay for up to three years. Koalas become mature when they are about two years old, but they often have their first baby after another two years.
The koala is not an endangered species, but it is a near vulnerable species. One reason is the loss of habitat, which means that koalas have less space to live. In some places there are very few koalas left. But there are also places, such as French Island (Victoria), with too many koalas that eat too much. Because of this the eucalyptus trees and other animals are in danger. A study looking at koala numbers at 1800 sites for 20 years, shows that the number of koalas is falling. The study, by the Australian Koala Foundation, estimates that there are only about 50,000 koalas left.