Animal Diaries Archive

A koala joey's journey

28 October 2005

A koala is a marsupial that gives birth after an average 34 to 36 day gestation or pregnancy period. At birth the koala young measures around 2.5cm (1 inch) in length and weighs approximately 1 gram. The young finds its way from the birth opening to the mother's backward facing pouch assumedly unaided. The modified structure of the pouch - being reversed - enables the koala to raise their young in a way that is suited to their lifestyle.

Once in the pouch, the young will suckle from only one of the two teats for the entirety of the suckling period. This period can last upward of nine months. For the first six months the young undergoes its most rapid growth and development. Within this short time, feeding only on the mother's rich milk, the joey transforms from being underdeveloped and translucent-skinned young, to a fully developed, yet not fully grown, distinguishable koala with a thin covering of fur all over the body.

When the joey reaches this point it is then time for it to obtain a substance referred to as pap. Pap is a type of modified faecal output that provides koala young with essential gut flora enabling them to move on to a solid diet. It is partly due to a symbiotic bacterium that the koala can digest the very fibrous and toxic eucalyptus leaf and it is only through eating this pap that a joey may acquire this bacterium.

Usually at about six months of age, koala joeys will start to stimulate their mother's cloaca to produce pap and may have anywhere up to six feeding sessions during the space of two months. During this time they will also nibble on the leaves to get a taste for them and to test out their new gut flora.

Here at the Zoo we have a new joey that will be starting to pap feed very soon. Keep your eyes peeled while visiting and you might just be able to view this amazing event.