A newborn koala, or Joey, is tiny and helpless. It weighs just one- hundredth of an ounce (0.5g) and is smaller than your thumb.

For the first few months the Joey stays inside its mother’s pouch, feeding on her milk. The pouch entrance remains closed.

By the age of 5 months, the Joey’s eyes are open and it can look out of the pouch. It still stays there and feeds on its mother’s milk.

About six months after Joey is born, its eyes open. It is now ready to see and explore the world outside. The Joey leaves its mother’s pouch for the first time for a short time, but it hangs onto its mother’s chest or back. It gradually moves farther, but it dashes back to the pouch if danger threatens it.

It is now about 8 in. (20 cm) long and weighs nearly 18 oz. (500 g) has eyes, ears, and fur. It crawls in and out of the pouch. It keeps very close to its mother and returns to the pouch within a few minutes gradually the outings become longer.
It begins to spend short periods of time outside the pouch. The Joey’s body is completely formed, but it is still growing. Now, instead of nursing inside the pouch, the Joey lies on its mother’s stomach to feed.

By this time the Joey begins to want more to eat than just milk.

By the seventh month, the Joey is ready to add something new to its diet. The mother begins to feed it eucalyptus leaves that she has chewed and begun to digest. This semi – liquid mush is pap.
So the mother gives her baby a food called pap, which is partly digested eucalyptus leaves that she has pre–chewed. The baby likes this new food. Pap gives the Joey a little taste of eucalyptus and prepares its stomach for digesting solid leaves.

By 8 months old, a Joey can pull itself out of the pouch. The Joey clings to its mother’s belly as she climbs through the trees. If it feels frightened or tired, it can always go back into the pouch. As it grows bigger and braver, the koala baby begins riding piggyback or on top of its mother’s head.

At 9 months old, the young koala is too big for its mother’s pouch and rides her back.

At 9 months old, the Joey weighs 2.2 lbs. (1kg). It is now too big for the pouch and rides on its mother’s back. Joey and mother keep in contact among the leaves by soft squeaks and hums. If the Joey wanders too far, the mother grunts angrily to summon it back.

The Joey is weaned at around 10 months, but stays near its mother for another two. By the time a year has passed, the mother may have mated again and have another Joey growing in her pouch.

By 12 months old, the Joey wants to eat only eucalyptus leaves. No more mothers’ milk and no more pap. The mother koala begins teaching her baby which eucalyptus leaves are good to eat.

When a Joey is about a year old, it gradually stops eating pap and drinking its mother’s milk. It starts to eat only eucalyptus leaves. As it grows bigger, the Joey learns to climb trees and find food on its own. It is almost an adult.

A one–year–old koala can live on its own, but it rarely does. Most young koalas stay with their mothers until they are two or three years old. A mother and her Joey are the only koalas that live together and share the same tree.

When it is three years old, the koala is an adult. It is now ready to have babies and start a new life cycle.

Koalas are not really fully grown until they turn 4 years old. Scientists say koalas in the wild usually live between 10 and 14 years.