A koala looks like a really cute bear but is actually a marsupial, like its relative the kangaroo. Marsupials have pouches for their newborns. The koala was named “Phascolarctos cinereus" or “ash grey pouched bear” in the early 19th century. The word “koala” may mean “no drink” in the Aboriginal language, or “biter” or “angry” because koalas bite and scratch when mating or if they are frightened.

Trees are central to a koala’s existence. Each koala has home trees that it visits often, as well as a home range of trees that may overlap the ranges of other koalas. The scope of the home range varies depending on the particular habitat and the gender, age and social position of each animal. Koalas do not visit each other’s trees unless it’s breeding time. Intact food trees are vital to the existence of koalas and when they are removed or entire forests are cleared, it is a threat to the entire group.

The koala is one of three mammals, including the greater glider and ringtail possum, that can survive on eucalyptus leaves. Although there are more than 600 varieties of eucalyptus, koalas are fussy eaters and won’t eat all of them. They will patronize a few species called “primary browse trees”, and sometimes eat non-eucalyptus trees for variety, or just use them for sitting or sleeping purposes.

Koalas can eat over two pounds of leaves every night, and even with the help of a very long organ called the cecum that contains the appropriate bacteria to break down the fiber, they absorb only about a quarter of what they’ve eaten. So they have to eat quite a lot of leaves to get enough nutrition. Koalas don’t need to drink unless there is a drought and the leaves don’t provide them with enough moisture. Their teeth have evolved to deal with their specialized diet. The sharp front incisors are for nipping the leaves from the tree and their molars allow the koala to cut and shear as well as crush the leaves. The diastema, which is a gap between the incisors and the molars, works with the tongue to move the leaves around the mouth.

Curiously, a microscopic organism called Chlamydia lives in the body of healthy koalas and helps limit the population to prevent overbrowsing and ensure survival of the fittest. Occasionally Chlamydia can make koalas sick, particularly in times of environmental stress.

Koalas have probably been around for 45 million years. There is probably only one species, although some scientists classify them into two or three subspecies. Southern koalas are bigger than Northern koalas, with thicker fur, probably because of the colder winters there.

Breeding females produce one joey a year, although older females may not breed every year. The koala mother’s tiny joey is born naked, blind and earless and must make an epic journey from the birth canal to the pouch. With its senses of smell and touch, powerful front legs and claws and an inborn sense of direction, it heads for its mother’s pouch, where it remains for about seven months attached to one of the pair of teats, drinking milk at first, and then a substance called pap after six months. Pap comes from its mother’s intestines and contains important bacteria that the joey will need to digest its principal food, eucalyptus leaves, which are also known as gum leaves. At about seven months it exits the mother’s pouch to start eating leaves on its own but returns to the pouch until it is about one year old and too big to fit. After one to three years the joey leaves its mother’s home range to find its own territory.

Female koalas mature by two years of age and males by four, and they have to find their own home ranges by that time. Koalas need large areas for their habitats because each forest can only contain a certain number of koalas, called its “carrying capacity”.

Koalas have no tail but an excellent sense of balance because of their lean, muscular bodies and long, powerful limbs that help them climb. Their paws are designed to grip and climb trunks and branches, with their rough palm and sole pads and long, sharp claws. In addition, there is no claw on the biggest digit of the hind paw, and it is opposable to the other digits for better gripping. The second and third digits are fused to form a grooming digit. The front paws have five digits, two of them opposable for better climbing and gripping food. Interestingly, like humans, koalas have individual fingerprints.

Koalas have large, leathery noses with a highly developed sense of smell to help them differentiate between different eucalyptus leaves and detect toxicity levels as well as smell scent warnings of other koalas. Their ears are also large because they need to keep in touch with others within a large territory. But their eyes are small because sight isn’t as important in their world.

Male koalas are called bucks and females are does. Breeding males have a dark scent gland that exudes a sticky substance in the middle of their chests for marking home trees, and females and young males have plain white chests. Koalas are mostly nocturnal and sleep up to twenty hours a day because they require a lot of energy to digest their high-fiber, low-nutrition, rather toxic eucalyptus leaf diet.

Koalas employ a variety of noises including a bellow, which is a snore-like sound along with a belch. Males bellow more than females, but females also use sounds to express aggression and sexual needs. Mothers and joeys communicate with clicking, squeaking sounds or humming, murmuring, grunting sounds. The fear call used by both sexes sounds like a screaming baby and sometimes includes shaking.

The life span of a koala varies widely. In the wild under ideal conditions they can live up to ten years. Males tend to live shorter lives than females because of breeding season fights and the fact that they need to move around more. Also, the teeth of koalas eventually become ground down from their diet and don’t grow back so that they can no longer get enough nourishment, and they die from starvation. In captivity, koalas can live longer. One koala named Sarah lived at an Australian sanctuary until she was 23 years old, and a male named Tam Tam died at the age of 22 at a Japanese zoo.

Koalas once served as an important food source for Aborigines, but when the Europeans arrived in Australia in the late 18th century they began to be killed for their pelts. This massacre continued until the 1930s, at which point they were declared a protected species, although their food source, the eucalyptus, was not protected along with them. Natural predators of koalas include foxes, feral cats, dingoes, owls, eagles, and pythons, but their biggest enemy is loss of habitat due to human development. Koalas trying to survive in damaged habitats can die of car accidents, dog attacks, malnutrition and disease. The Australian Koala Foundation estimates that some 4,000 koalas are killed annually by cars and domestic dogs. There are probably less than 100,000 wild koalas left in Australia due to the disappearance of 80% of their habitat from land clearing, fires, and eucalyptus diseases. Wild koalas are now only found in the mainland of eastern Australia and on a few islands off the southern and eastern Australian coasts.

In an effort to save the koala, populations have been transplanted from one part of Australia to another, particularly to Victoria, but this has resulted in inbreeding and even overpopulation in certain areas. The IUCN (International Union for Conservation of Nature) lists the koala as only “Potentially Vulnerable”, although it is considered “Threatened” according to the U.S. Endangered Species Act. Even with legal protection, in Australia about 80% of koala habitat is on private land, which is almost never protected. Sadly, these unique creatures, who once numbered in the millions, may be reduced in the not-so-distant future to nothing but zoo relics if more is not done soon to save what’s left of their fragile homes.

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