( Phascolarctos cinereus )
The Koala is the only member of the Phascolarctidae family. The Koala’s scientific name Phascolarctos cinereus means ‘ash-coloured pouched bear’.
Is it a bear?
Some people refer to the Koala as a Koala Bear. Although it looks like a small bear, the Koala is a marsupial mammal.
Female marsupials have pouches to carry their babies. Other marsupials include kangaroos, wallabies, wombats, possums, and opossums. The Koala’s closest relative is the wombat.
In Aboriginal language, the word Koala is thought to mean ‘does not drink’.
Koalas have soft, wool-like grey fur, which is paler on their undersides. They have patches of white on their stomachs, chests and chins and a fringe of white around their ears. They have a large, round head with large, round, furry ears, a large nose and long strong limbs with sharp claws. They have a small tail, hidden by their fur.
A Koala’s front and rear paws each have five digits with sharp claws. Their hands have two opposable thumbs, much like a human’s thumb, and three fingers, which help them with climbing and gripping tree branches. Two toes on their rear feet are joined together to form a ‘grooming claw’ useful for removing tics and combing their fur. The big toe doesn’t have a claw.
Koalas vary in size and colour depending on where they live in Australia. Koalas living in the southern parts have adapted to the colder climate. They are larger and have thicker, grey coloured fur. Koalas from the warmer northern areas are more a browny colour and smaller.
Koalas reach a maximum length of about 24 – 34 inches (60 – 85cm). An adult male koala can weigh between 17 – 30 pounds ( 8-14 kilograms) and a female between 13 – 25 pounds (6 - 11 kilograms). They have a life span of between 12 and 15 years.
Koalas are found along the eastern coast of Australia, from the Atherton Tableland west of Cairns in Queensland, down through New South Wales, Victoria and South Australia . They also live on islands off the coast of Queensland, Victoria and South Australia.
Their habitats range from tall eucalypt forests and low woodlands inland, to coastal island trees.
Koalas eat only leaves and bark from eucalyptus trees. There are over 600 types, or species of these trees, but Koalas only eat the leaves and bark from 12 of them.
Eucalyptus leaves are extremely poisonous to most animals but the Koala’s digestive system detoxifies the poison. Each Koala eats approximately 12 – 21 ounces (350 to 600 grams) of leaves a day. They prefer the ‘tip’ of the leaves, which is the juiciest and softest part of the leaf.
Koalas receive over 90% of their fluid intake from the Eucalyptus leaves. They only drink water when they are ill or when there is not enough moisture in the leaves.
Koals are mostly nocturnal. They spend up to 20 hours a day sleeping or resting in trees, curled up gripping the limbs with their feet. When they move around, they can leap from tree to tree as well as travelling longer distances on the ground. They walk with a slow akward gait, moving very slowly, but they can break into a run if threatened.
When travelling on the ground, they can be attacked by predators such as dogs, foxes and dingoes and they are also at risk of injury or death from cars.
Koalas are very territorial and live in stable breeding groups. Each animal has its own ‘home trees’, and the area covered by these trees is called the koala’s ‘home range’. The size of each home range depends upon the sex, age and social position of the animal within the group. Koalas do not normally visit each other’s home trees, except for breeding.
Koalas are generally silent but can communicate with a wide variety of sounds including growls, grunts and a load bellow. The mating call of the male koalas can be heard for long distances during breeding season.
The Koala's very large nose is one of its most important features. It has a very highly developed sense of smell, which helps the animal tell what eucalyptus leaves are safe to eat.
Koalas have a very low metabolism, which conserves energy and helps with digestion of the fiborous eucalyptus leaves. They feed at any time of day, but usually in the cool of the night to conserve energy and moisture.
Eucalyptus leaves are poisonous to most animal and are not high in nutrients. Koalas have a special bacteria in their stomachs that breaks down the toxins in the eucalyptus oil. Koalas chew the eucalyptus leaves to a very fine paste before swallowing. Their hind gut (the caecum) is enlarged and contains bacteria which ferments the leaves and extract the maximum amount of nutrient from them.
A baby Koala is called a joey. Koalas breed once a year between December and March (the Southern Hemisphere’s summer) and give birth to only one baby at a time. Gestation is 35 days. At birth, the joey is very small, about the size of a jelly bean. It measures less than 30 millimeteres in length and weighs less than 1 gram. It has no ears or hair, and it can't see.
As soon as the joey is born, it makes a long journey, crawling across its mother’s fur and into the pouch on her belly. A female koala's pouch opens near the bottom instead of at the top like a kangaroo pouch. The baby Koala attaches itself to one of two teats inside the pouch and the mother's powerful muscles hold the joey so it can't fall out. It stays hidden there for about six months, feeding on milk. During this time the joey grows ears, eyes and fur.
At about 30 weeks, when the joey is ready to be weaned, the mother produces a special faeces from her anus called “Pap” which the joey licks from her fur. This is similar to a human baby being fed mushy food before going on to solids. The Pap is high in nutrients and micro-organisms from the mother’s own digestive system and helps the baby koala to begin to digest eucalyptus leaves.
The joey leans out of the pouch to look around, and then starts to explore outside. It stays with its mother for another six months or so, riding on her back, and feeding on both milk and gum leaves. Weaning is complete at about 12 months of age and after this, Koalas gradually become independent and survive on their own.
Protecting the Koala
Once there were millions of Koalas, but in the early 20th century the animal was hunted almost to extinction. In the 1920s nearly eight million koalas were killed, largely for their fur.
Koalas require large areas of healthy forests that are connected together, and they will travel long distances along tree corridors in search of new territories and mates. When their habitats are destroyed, they have to travel further and more often. They also have to move along the ground more often, and so are at greater risk from predators and humans.
The most common causes of koala deaths are dog attacks and motor vehicle accidents. In recent years some colonies of koals have been hard hit by disease.
There are now many conservation and research programs to help protect the Koala and its habitat.