The koala has a small, compact body (28-32 in.), a vestigial tail and large ears. Males, at about 26 lbs., are larger than the 17 lb. females. Males have a scent gland on the chest and females have a rear-facing pouch. The koala is adapted to its almost exclusively arboreal life. The large paws have long claws for grasping tree limbs. The dense woolly fur, gray above and white below, makes the koala extremely difficult to see. Their hands have two opposable thumbs and three fingers.
The koala is mostly nocturnal and usually solitary. They are accomplished climbers and can rapidly ascend a tree in a bounding movement. On the ground they move in an unhurried quadrupedal walk, but can move quickly if the situation demands it.
Koalas typically associate only for mating. Their low quality diet of leaves provides little usable energy and the koala typically sleeps 18 hours per day.After a short gestation period the female licks a trail of saliva from the pouch to the cloaca. The joey emerges and follows that trail up to the pouch, where the mammary glands are. After about 5 months it climbs out of the pouch and onto the mother's back, where it stays until it is about a year old. It makes the transition from milk to solid food by eating partially digested leaves from the mothers cecum. Females bear one young every two years. Females will also adopt abandoned babies.