Koalas are known worldwide as one of the symbols of Australia. Their gray and white fur, broad head, small eyes, large furry ears, and round belly make them appear cuddly like a teddy bear.
Koalas range in size from 24 to 33 inches (60 to 85 centimeters) and in weight from 8.8 to 33 pounds (4 to 15 kilograms). This is an unusually large size range. Koalas living in the northern (warmer) part of their range are on average 45 percent smaller than those in the southern (colder) areas. In addition, males can be up to 50 percent larger than females.
Koalas are arboreal, meaning they live in trees. They have strong arms and legs with five toes that end in sharp curved claws to help them climb. The first two toes on the front legs are opposable. This means that these toes, like the thumb on a human hand, can reach across and touch the tip of the other three toes (unlike, for example, a dog paw or human foot, where none of the toes can bend to touch each other). This adaptation helps koalas to grasp branches and climb. The first toe of the hind food is short, broad, and clawless. It is also helpful in gripping branches. As in all members of the order Diprotodontia, the bones of the second and third toes of the hind foot are fused. This condition is called syndactyly (sin-DACK-tuh-lee). The single fused bone, however, has two separate claws. This twin claw is used in grooming.
Koalas do not build nests or live in dens. Their fur protects them from the weather. As a result, the fur of animals living in the colder regions of the range is thicker than that of animals living where it is warmer. In the past, many koalas were killed for their fur. Males have a gland on their chest that produces scent used for marking trees to warn off other males and establish their own individual territory. Females have a backward-opening pouch in which they carry their young. Koalas also have a tiny brain. It is only 0.2 percent of their body weight.