The koala is a tufted-eared marsupial, with its primary habitat in Australia. Some koalas have been relocated to islands surrounding Australia, but most koalas make their home in Eastern Australia. Evidence of koala populations in other parts of Australia exists, but most lost their habitat due to increased building and human encroachment on habitat. The koala is now considered a threatened species.The koala is arboreal, which means they live in trees. They also have a slow metabolism, which is the reason they spend almost 20 hours of the day sleeping. At birth, they are minuscule, about the size of a jellybean. They also lack their trademark fluffy ears and eyes. At about six months, the baby koala more resembles a mature koala, and ventures out of the pouch to eat its mother’s excreted and digested eucalyptus. By a year, the baby will spend most of its time outside the pouch, and eat the primary koala diet of eucalyptus leaves, and occasionally bark. A full-grown koala may be about 17 pounds (7.71 kg), though this varies according to sex. The adult koala is about two to three feet (0.6 - 0.91m). Males are larger than females. The koala will reach sexual maturity at about two to three years of age, and the female will have about twelve babies in a lifetime, each born singly. Koalas in the wild live approximately 15-18 years. In addition to the large ears, koalas have a large brown to black nose. They have dense grey to grey-brown fur, with white or cream markings. The fur of the koala made them attractive to hunters who pushed the species to near extinction by overhunting. This practice stopped in the mid-20th century and efforts were made to preserve the remaining species. These efforts have been fairly successful, though the threatened status of the koala is still a concern because of habitat loss.Koala populations have also suffered where they have been relocated. The koala population on Kangaroo Island has led to extreme overpopulation and illness. While efforts are underway to curb population expansion, overwhelming community support for the koala will not allow the animals to be killed. Relocation back to the mainland of Australia has not been successful. Strategies for reducing population currently involve shooting hormone filled darts at female koalas to prevent reproduction.The koala cannot be called an exceptionally intelligent animal. It has a very small brain that only occupies about 40% of its cranial cavity. On a typical day, the koala eats, sleeps and takes care of its young. Though it has tremendous visual appeal, approaching a wild koala is not recommended. They can be quite grumpy, and their sizable claws and strong bite are to be avoided. As well, the mainland koala population is currently suffering from an outbreak of chlamydia, which could be transmitted through a bite.Though the koala is often called a koala bear, the koala is not related to bears. One of its main distinctions from bears is that it is a marsupial. It has a much closer relationship to the wombat, and other marsupials of Australia and Tasmania.