Marsupials of Australia

The Koala

The koala is a tree-dwelling marsupial and an iconic Australian symbol along with such animals as the kangaroo, wombat and platypus. The Latin name (Phascolarctos cinereus ) means ash-coloured(cinereus) pouched (phaskolos - pouch) bear (arkton – bear) but the koala is not actually related to bears.

The first European to record koalas was John Price in 1798. During the early days of Australia's settlement, koalas were hunted for their thick woolly pelts. So many were slaughtered that by 1924 they were in danger of becoming extinct. Late in the 1930s, they were declared a 'protected species'.

The koala is endemic to the eastern parts of Australia.

Koala(73204)Credit: Vince Evans - Copyright

Koalas are extremely selective in their feeding habits and frequent areas which support the eucalypts that they need as food.

Koalas in the southern parts of the range are generally larger in size and have thicker, denser fur to cope with the cold. Mature koalas weigh between 6 to 14 kg depending on sex and location.

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The koala varies in colour from light grey to brown. There are generally patches of white on the chest, neck, ears and inside the legs. The rump is often speckled. There is a cartilaginous pad over the end of the curved spine. This area is densely packed with fur and provides a comfortable 'seat' for the many hours that koalas spend sitting in tree forks and on branches.


There are five digits on the front paws. Two are opposable which aids in holding branches and food. The second and third digits on the hind feet are fused forming a grooming claw.

The koala has adaptations that suit it to climbing. The body is lean and muscular and the thigh muscle joins the shin low down which gives a lot of climbing strength. They have excellent balance. To climb, the koala grasps the trunk with two feet and ascends in a series of bounds, leaving parallel claw marks on the trunk.

Mature males exude a dark, sticky substance from a brown 'scent gland' in the middle of the chest. By rubbing the chest on trees, males mark their territory.

 Koalas do not have good eyesight but have a keen sense of smell. This allows them to differentiate between different types of gum leaves. The levels of toxicity in gum leaves can also be ascertained by scent.

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Koalas can run quite quickly on the ground. They can also swim and climb well.

The metabolic rate of koalas is very slow. Digestion of the leaves takes most of the koalas energy and they sleep 18 to 20 hours each day. Ninety percent of their water requirements is obtained from gum leaves. They will normally only drink when they are ill or when there is insufficient moisture in the leaves.

Sleeping Koala

Out of 40 to 50 species of eucalypts which koalas will eat, ten make up their favourites. There are a few non-eucalypts which also provide food. Each habitat area has specific species of trees which koalas in that area will eat. Eucalyptus leaves are poisonous to most animals. They are low in nutritional value and very fibrous.

Koalas are territorial and if a koala dies, his territory won't be taken over until the scent markings and scratches on the tree bark have disappeared. Such habits can make it very difficult to relocate koalas which have been rescued. Individual areas overlap and socialisation takes place in these areas.

Koalas communicate by a variety of sounds. During the mating season there is a lot of deep, grunting bellows, mostly by the males. Softer squeaks and murmurs occur between mothers and their offspring.

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The breeding season is from September to March. Females normally breed only every two or three years. In the average female's life span of about twelve years, one female may produce only 5 or 6 offspring.

About 34-36 days after conception, the hairless baby which is about the size of a jelly-bean, claws its way up and into the pouch. A baby koala is called a joey. Joeys are born blind and without ears.

Cute Koala Baby

Once in the pouch, the joey takes hold of one of two teats; the teat swells to hold the baby secure and a sphincter muscle closes the pouch keeping the baby safe inside. The eyes open at around 22 weeks. From that point to 30 weeks, the joeys are fed 'pap', a specialised form of soft, runny faeces produced by the mother. Pap is rich in protein and contains micro-organisms essential for the digestion of eucalyptus leaves. By now the joey is riding on the mother's back. Although he has become too big for the pouch, he still needs some milk and the teat elongates to protrude from the pouch for this purpose.

Adult males may live to ten years in the wild but near human habitation, the lifespan is more likely to be two or three years.

The wild koala population is under threat from a disease called chlamydia which causes pneumonia, urinary and reproductive tract infections (resulting in infertility) and conjunctivitis. There is a school of thought which believes chlamydia is Nature's way of controlling the population in times of stress. Symptoms include chest infections, sore eyes, and "wet bottom" or "dirty tail".

The koala, like many native animals, is having a bit of a battle but hopefully he will be around for a long time yet.

Image Sources

About Marsupials: A Guide for Children (About... (Peachtree))
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A range of marsupials are discussed
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