A koala is a tree-dwelling marsupial from Australia with thick gray fur, a large black nose, and round fluffy ears. Koalas spend most of their lives in eucalyptus trees, sleeping up to 20 hours a day and eating eucalyptus leaves, which are tough, low in nutrition, and actually poisonous to most other animals. A koala's digestive system has specially adapted to break down these toxic leaves safely.

Though they look cuddly like teddy bears, koalas are wild animals with sharp claws for gripping branches and surprisingly loud, grumpy voices. Despite their name, koalas aren't bears at all. They're marsupials, which means mothers carry their tiny babies in pouches, just like kangaroos do. A newborn koala is only about the size of a jellybean.

Koalas move slowly and deliberately through the trees, conserving energy because their eucalyptus diet doesn't provide much fuel. They rarely come down to the ground except to move to a new tree. Today, koalas face threats from habitat loss and disease, making conservation efforts important for their survival in the wild.