Integumentary and Skeletal/Muscular Systems

Koalas have a dense, wooly coat of ash-colored to dark brown and white fur.
Male koalas are very territorial and have a specialized brown scent gland on their chest that they use to rub their scent on trees to deter other males.

Koalas are vertebrates so they have a backbone.

The koala is an herbivore so it only eats plant matter.
Therefore, it has specialized teeth in its skull to help grind up the plant fiber in eucalyptus leaves.