Koala

## Description

The koala or, inaccurately, koala bear (Phascolarctos cinereus) is an arboreal herbivorous marsupial native to Australia. It is the only extant representative of the family Phascolarctidae and its closest living relatives are the wombats. Because of its distinctive appearance, the koala is recognized worldwide as a symbol of Australia. They were hunted by Indigenous Australians and depicted in myths and cave art for millennia. The first recorded encounter between a European and a koala was in 1798, and an image of the animal was published in 1810 by naturalist George Perry.

## Appearance

Koala is a charming marsupial with a thick-set body, small eyes, and large ears. The wool-like coat of the animal is thick but soft, colored with ash-grey. The densely packed fur on the bottom serves as a cushion, allowing koalas to sit upon rough tree branches. The underparts as well as the tips of hairs on their ears are white. In the center of their chest, adult male koalas have the identifying brown-colored "scent gland". One of the key characteristics of this animal is a very strong sense of smell, which helps them distinguish between poisonous and eatable leaves. They have large sharp claws on their long limbs, which help them in climbing trees, as well as 5 digits, including opposable thumbs, allowing them to grip tree branches and food.

## Distribution

Koalas are distributed across eastern and southeastern Australia, including northeastern, central, and southeastern Queensland, eastern New South Wales, Victoria as well as southeastern parts of South Australia. They can be found in habitats ranging from relatively open forests to woodlands, and in climates ranging from tropical to cool temperate. In semi-arid climates, koalas prefer riparian habitats, where nearby streams and creeks provide refuge during times of drought and extreme heat.

## Lifestyle

Koalas are asocial animals, congregating only during the breeding season. They usually form large, loosely organized groups in areas with abundant suitable trees, with a single individual per tree. During the rest of the year, koalas tend to live solitarily, showing very little social behavior. They are arboreal animals, dwelling in trees. Koalas are exceptionally good climbers. Meanwhile, when on the ground, they are very slow walkers. During the daytime hours, these nocturnal animals usually sleep on the fork of eucalyptus trees. Normally, koalas are quiet animals. However, when threatened or alarmed, they typically give out a call, reminding the cry of a human baby, and accompanying it by shaking. In addition, during the breeding season, males of this species begin to emit bellowing calls. Koalas also scent-mark their trees, which is a form of communication.

## Diet

Koalas are herbivorous (folivorous) animals, feeding primarily upon the leaves of the eucalyptus tree. Meanwhile, they consume the leaves of 30 various species of the eucalyptus tree and supplement their usual diet with foliage from acacias.

## Reproduction

Koalas have a polygynous mating system with the dominant male, mating with most females. Koalas mate from December to March. The gestation period in koalas lasts for only 35 days, yielding a single baby. During the first 5-6 months of its life, the joey lives in the pouch of its mother, feeding exclusively on milk. By the age of 6 months, the young is weaned. The young then starts feeding upon pap - partially digested vegetation, found in the excrement of its mother. At 7 months old, the baby comes out of the pouch of its mother, beginning to cling to her back. Then, at about 1 year old, the young koala becomes independent, after which the youngster typically stays with its mother for another few months before it leaves. Male koalas reach sexual maturity by 3-4 years old while females are mature at 2-3 years old.

## Population

### Population threats

The primary threat to the koala population in Australia is the destruction, fragmentation, and alteration of their natural range, due to which the animals are often hunted by dogs as well as colliding with vehicles. Other notable threats include diseases and bushfires. The animals are also exposed to drought, which leads to a considerable number of mortality in certain populations of koalas.

### Population number

According to IUCN Red List, the total population size of the koala is around 300,000 mature individuals. Currently, this species is classified as Vulnerable (VU) on the IUCN Red List, and its numbers today are decreasing.

## Fun Facts

Koalas spend most of the day (up to 18 hours) sleeping.

The brain of the koala is less than 0.2% of the animal's body weight. This, combined with their nutrient-poor diet, is the reason for koalas' sedentary lifestyle.

Their name, "koala", comes from the Aborigine language and means "no water". The animals are so called because they rarely drink water and attain the required moisture from eucalyptus leaves. However, when the temperatures increase, koalas sometimes lose a large amount of water, becoming dehydrated.

A koala consumes about 1 kilogram of leaves per day on average, which is a huge amount for the body size of the animal. They also tend to use their cheek pouches as stocks, where they store snacks of leaves.

Koalas feed upon leaves only during a certain stage of growth. They consume 12 species of eucalyptus tree out of more than 100 species, found throughout Australia.

Not only koalas are excellent climbers, but they are also good swimmers, known to cross rivers, escaping from heavy flooding in their home range.

Newborn babies of this species are hairless, blind, and as small as a broad bean.

The mother and her young are in very close bonds; the female is happy to carry the joey with her everywhere, until the baby grows old, and becomes independent.

Their scientific name is "Phascolarctoscinereus”, where the Greek word "phaskolos" means "pouch", arktos means "bear" and the Latin word "cinereus" means "ash-colored".

## Other References

https://en.wikipedia.org/wiki/Koala

https://www.pbs.org/wnet/nature/blog/koala-fact-sheet/