Koala bears, often simply called koalas, are marsupials native to Australia. They are known for their distinctive fluffy ears, large black noses, and gray fur. Koalas primarily inhabit eucalyptus forests, where they spend most of their time in trees. Their diet consists mainly of eucalyptus leaves, which are low in nutrients, so they conserve energy by sleeping up to 18 hours a day. Despite their common name, koalas are not bears; they are more closely related to wombats and kangaroos. Koalas have a unique reproductive system, giving birth to underdeveloped young that continue to grow in their mother's pouch. Conservation efforts are ongoing to protect their habitats from threats like deforestation and climate change.