Full classification, kingdom through to species:
Kingdom: Animalia, Phylum: Chordata, Class: Mammalia, Infraclass: Marsupialia, Order: Diprotodontia. Suborder: Vombatiformes. Family: Phascolarctidae, Genus: Plascolarctos, Species: P. cinereus
The koala’s body is designed for a life in the trees. They have four limbs, each ending in a set of hooked claws and rough palm pads specifically designed for gripping and climbing. They are also quite strong and have especially powerful hind leg muscles. Their limbs are long in comparison with their body size to help them reach branches. Their arms are almost equal length with their legs. Females are usually between 65cm and 73cm long and males are between 67cm and 82cm long. Males are also often heavier than females, weighing between 8 and 15 kilos compared to females which weigh between 4 to 9 kilograms.
Females have a stomach pouch for carrying young and both genders are coated in a layer of thick fur which is designed to protect them from rain and unusually high or low temperatures. Their fur is often white around the stomach, neck, underarms, inside their ears and on some areas of the face and the rest of the fur is grey. They have a powerful skull and teeth designed to grind up and tear at leaves. Baby koalas are born blind and whilst they develop the ability to see, at no point in their life is sight the sense that they rely on the most. They possess an unusually large nose and ears, which they rely on to detect important smells and sounds. They are able to smell the levels of toxicity in eucalyptus leaves and the scents produced by possible mates and their competition.
They don’t have an external tail but still have excellent balance, which they use to avoid falling from high branches. There are two main types of koalas, the Southern koala and the Northern koala. The koalas from the South are larger than those from the North and have much thicker and browner fur as well. This is because they need more fur to be able to stay warm through colder winters. The koala has a small brain in comparison to its body and this is thought to be an adaptation to help koalas live using less food, as the brain demands lots of energy.
Koalas live in a range of different bushland areas located in parts of Queensland, New South Wales, South Australia and Victoria. They can be found in coastal island areas, tall eucalypt forests or low eucalypt woodlands. For their habitats to be suitable, they must have the right trees for koalas to eat and sleep in and water available. A forest can only support a limited number of koalas because they all compete for the same food source. Habitat destruction is the biggest threat to koalas and 80% of their habitat has already been destroyed. Roughly 4,000 koalas are killed each year by dogs and cars because they are forced to move to find a new habitat.
Koalas are marsupials, meaning that they give birth to live babies, which are not completely developed. The female then carries and suckles the baby (called a joey) in their pouch located on their lower stomach until their baby has grown enough to come out. Usually the joeys stay in their mother’s pouch for 6-7 months. During this time they rely on their mother completely as they are born about 2cm long without fur, sight or developed ears.
It attaches itself to one of its mother’s teats and drinks milk for the majority of its time in the pouch. For the last few weeks while it is in the pouch it adds a substance called “pap” to its diet. This is a special type of soft and runny droppings produced by its mother. Microorganisms from the mother’s intestines are present in the pap. This is why once the joey has eaten pap for long enough, it will be able to tolerate gum leaves like its parents.
The joey rides on its mother’s back or stomach for a while after it comes out of the pouch and leaves its mother between the age of 1 and 3 years old. This often depends on when the mother has another joey she needs to look after. Male and female koalas usually mate when they are 2-3 years old, between December and March. Koalas make deep bellowing calls and scents to attract a mate.
To the majority of animals, eucalyptus leaves are extremely poisonous but the koala’s system has developed immunity to their toxins. The eucalypt leaves are integral part of koala’s diets and they are their main source of energy. The leaves are low in nutrients but high in fibre and the koala’s slow metabolic rate allows them to maximise the amount of nutrients being extracted from the leaves. Each day they consume between 200 to 500 grams of them.
They also have an unusual fibre digesting organ called a caecum which is very long (200cm) compared to those other mammals such as humans have. The bacteria it contains is able to break fibre down into more useful substances that the koala’s body can absorb for energy. The reason they need to eat such large amounts of leaves is that despite their systems’ adaptations, only 25% of the fibre they eat is absorbed.
Usually, it is not necessary for koalas to find water to drink as they extract moisture from the gum leaves they consume. The main time they need to seek out additional moisture is when the country is experiencing a drought and the leaves have lower levels of moisture. There are over 600 types of eucalypts and koalas only eat some of these. There are some types of leaves that they prefer over others and there may be only two or three types of species that the koalas will eat in any one area. They eat other types of leaves occasionally and don’t always use eucalypts for resting.
- Koalas are the only other animal other than humans that have individual fingerprints.
- The koala’s closest relative is the wombat.
- The koala’s skeleton shows that in the past they had tails.
- Habitat loss is the greatest threat to koalas.
- Koalas are mostly nocturnal.
- Koalas often sleep for up to 18-20 hours a day.
- Male koalas have a scent gland on their chest which produces a dark, sticky substance. They rub this on trees to declare ownership of them.
- Females usually give birth to one baby a year but this decreases in old age.