Koalas in Australia
The Koala is a thickset arboreal marsupial herbivore native to Australia, and the only extant representative of the family Phascolarctidae. Although the kangaroo is known as Australia famous animal, the koala is its other famous animal. At times you will hear it referred to as a koala bear, however it is not related to a bear at all. The word koala is adapted form the aboriginal word meaning no drink. Koalas do not need to drink as they get all their nutrition from a diet of eucalyptus leaves. A koalas hands are designed for climbing, and each koala has his or her own home tree which is not visited by other koalas except during mating season.
This attractive and very slothful animal sleeps by day but often without attempting to hide. They have beautiful fur for which they have been terribly persecuted in the past when hundreds of thousands of koala skins were exported annually until protective laws were introduced. From near-extinction level have now increased but they are subject to various diseases and are vulnerable to many predators such as cats and dogs and often fall victim to bush fires.
Most marsupials are so efficient that they need to eat a fifth less food than equivalent sized placental mammals but koalas have taken this efficiency a step further. Several years ago, biologists announced that koalas are the only living creature that has brains that don’t fit their skulls. Instead they have a shriveled walnut sized brain that rattles around in a fluid filled cranium although this has been contested by other biologists. It is clear however that Koalas are not the Einsteins of the animal world and it is believed that they have sacrificed their brains to energy efficiency. Brains cost a lot to run: our brains weigh 2% of our body weight but use 20% of the energy we consume. Koalas eat gum leaves which are so toxic that they use 20% of their energy just detoxifying this food in their highly specialized digestive system, which leaves little energy for the brain.
Koalas produce one young each year. Their pregnancy last for only thirty-five days before giving birth. Most of the growth and development takes place in the mothers pouch. After six months, its mother begins to produce a substance known as pap, which the young feed on along with milk. Pap contains bacteria that will be needed to digest the eucalyptus leaves, when they become adults. At seven months they leave the pouch, and return only to nurse until they reach a year old.