AskDefine | Define koala

Dictionary Definition

koala n : sluggish tailless Australian arboreal marsupial with gray furry ears and coat; feeds on eucalyptus leaves and bark [syn: koala bear, kangaroo bear, native bear, Phascolarctos cinereus]

User Contributed Dictionary

see Koala

English

Pronunciation

Etymology

From Dharuk (Aboriginal language) gula or gulawany.

Noun

  1. A tree-dwelling marsupial that resembles a small bear with a broad head, large ears and sharp claws, mainly found in eastern Australia.

Scientific names

Synonyms

Translations

a tree-dwelling marsupial that resembles a small bear

Basque

Noun

koala
  1. koala

Dutch

Pronunciation

Noun

koala (plural koala's)
  1. koala

French

Noun

koala
  1. koala

Hungarian

Pronunciation

  • /ˈkoɒlɒ/|lang=hu

Noun

  1. koala

Indonesian

Noun

koala
  1. koala

Interlingua

Noun

koala
  1. koala

Romanian

Noun

koala
  1. koala

Spanish

Alternative spellings

Noun

  1. koala

Swedish

Noun

koala (p koalor, def sing koalan, def pl koalorna)
  1. koala

Turkish

Noun

koala
  1. koala

Extensive Definition

The Koala (Phascolarctos cinereus) is a thickset arboreal marsupial herbivore native to Australia, and the only extant representative of the family Phascolarctidae.
The Koala is found in coastal regions of eastern and southern Australia, from near Adelaide to the southern part of Cape York Peninsula. Populations also extend for considerable distances inland in regions with enough moisture to support suitable woodlands. The Koalas of South Australia were largely exterminated during the early part of the 20th century, but the state has since been repopulated with Victorian stock. The Koala is not found in Tasmania or Western Australia.

Names

The word koala comes from Dharuk gula. Although the vowel /u/ was originally written in the Latin alphabet as "oo" (in spellings such as coola or koolah), it was changed to "oa" possibly due to an error. The word is erroneously said to mean "doesn't drink". Other descriptive English names based on "bear" have included monkey bear, native bear, and tree-bear.

Variation

Although three subspecies have been described, these are arbitrary selections from a cline and are not generally accepted as valid. Following Bergmann's Rule, southern individuals from the cooler climates are larger. A typical Victorian Koala (formerly P. cinereus victor) has longer, thicker fur, is a darker, softer grey, often with chocolate-brown highlights on the back and forearms, and has a more prominently light-coloured ventral side and fluffy white ear tufts. Typical and New South Wales Koala weights are for males and for females. In tropical and sub-tropical Queensland, however, the Koala is smaller (at around for an average male and just over for an average female), a lighter often rather scruffy grey in colour, and has shorter, thinner fur. In Queensland the Koala was previously classified as the subspecies P. cinereus adustus, and the intermediate forms in New South Wales as P. cinereus cinereus. The variation from one form to another is continuous and there are substantial differences between individual Koalas in any given region such as hair colour. The origins of the koala are unclear, although almost certainly they descended from terrestrial wombat-like animals. Koala fossils are quite rare, but some have been found in northern Australia dating to 20 million years ago. During this time, the northern half of Australia was rainforest. The Koala did not specialise in a diet of eucalypts until the climate cooled and eucalyptus forests grew in the place of rainforests. The fossil record indicates that before 50,000 years ago, Giant Koalas inhabited the southern regions of Australia. The Koala fills the same ecological role as the sloth of South America.

Physical description

The Koala is broadly similar in appearance to the wombat (their closest living relatives. The Koala is one of the few mammals (other than primates) that has fingerprints. Koala fingerprints are similar to human fingerprints; even with an electron microscope, it can be quite difficult to distinguish between the two.
The teeth of koalas are adapted to their herbivorous diet, and are similar to those of other diprotodont marsupials, such as kangaroos and wombats. They have sharp incisors to clip leaves at the front of the mouth, separated from the grinding cheek teeth by a wide diastema. The dental formula for koalas is:
The male koala, like many marsupials, has a bifurcated penis. The female has two lateral vaginae, a feature unique to the Koala, and it has two separate uteri which is common to all marsupials.
The brain in the ancestors of the modern Koala once filled the whole cranial cavity, but has become drastically reduced in the present species, a degeneration scientists suspects is an adaptation to a diet low in energyhttp://findarticles.com/p/articles/mi_m1134/is_6_108/ai_55127881. One of the smallest in marsupials with no more than 0.2% of its body weighthttp://spot.colorado.edu/~humphrey/fact%20sheets/koala/koala.htm, about 40% of the cranial cavity is filled with cerebrospinal fluid, while the brain's two cerebral hemispheres are like "a pair of shrivelled walnut halves on top of the brain stem, in contact neither with each other nor the bones of the skull. It is the only animal on Earth with such a strangely reduced brain."
It is generally a silent animal, but males have a very loud advertising call that can be heard from almost a kilometre away during the breeding season. When under stress, Koalas may issue a loud cry, which has been reported as similar to that of a human baby. There is little reliable information about the lifespan of the Koala, but in captivity they have been observed to reach the age of 18 years. Mating normally occurs between December and March, the Southern Hemisphere's summer.
A baby Koala is referred to as a joey and is hairless, blind, and earless. At birth the joey, only a quarter of an inch long, crawls into the downward-facing pouch on the mother's belly (which is closed by a drawstring-like muscle that the mother can tighten at will) and attaches itself to one of the two teats. Young remain hidden in the pouch for about six months, only feeding on milk. During this time they grow ears, eyes, and fur. The joey then begins to explore outside of the pouch. At about this stage it begins to consume small quantities of the mother’s "pap" (formerly thought to be excrement, but now thought to come from the mother's caecum) in order to inoculate its gut with the microbes necessary to digest eucalypt leaves. The baby Koala will remain with the mother for another six months or so, riding on her back, and feeding on both milk and eucalypt leaves until weaning is complete at about 12 months of age. Young females disperse to nearby areas at that time; young males often stay in the mother's home range until they are two or three years old.

Ecology and behaviour

The Koala lives almost entirely on eucalypt leaves. This is likely to be an evolutionary adaptation that takes advantage of an otherwise unfilled ecological niche, since eucalypt leaves are low in protein, high in indigestible substances, and contain phenolic and terpene compounds that are toxic to most species. Like wombats and sloths, the Koala has a very low metabolic rate for a mammal and rests motionless for about 16 to 18 hours a day, sleeping most of that time. Koalas that are disturbed are known to be violent, their teeth and claws capable of causing considerable injury to humans; special handling requirements are as such applicable.
Handling of koalas has been a source of political contention due to these risks, which can also cause harm to the koala as well. Koalas spend about three of their five active hours eating. Feeding occurs at any time of day, but usually at night. An average Koala eats of eucalypt leaves each day, chewing them in its powerful jaws to a very fine paste before swallowing. The liver deactivates the toxic components ready for excretion, and the hind gut (especially the caecum) is greatly enlarged to extract the maximum amount of nutrient from the poor quality diet. Much of this is done through bacterial fermentation: when young are being weaned, the mother passes unusually soft faeces, called pap, which is rich in these bacteria, thus passing these essential digestive aids on to her offspring.
The Koala will eat the leaves of a wide range of eucalypts, and occasionally even some non-eucalypt species, but it has firm preferences for particular varieties. These preferences vary from one region to another: in the south Manna Gum, Blue Gum and Swamp Gum are favoured; Grey Gum and Tallowwood are important in the north, and the ubiquitous River Red Gum of the isolated seasonal swamps and watercourses that meander across the dry inland plains allows the Koala to exist in surprisingly arid areas. Many factors determine which of the 680 species of eucalypt trees the Koala eats. Among trees of their favourite species, however, the major factor that determines which individual trees the Koala chooses is the concentration of a group of phenolic toxins called formylated phloroglucinol compounds.

Conservation status

The Koala was hunted almost to extinction in the early 20th century, largely for its fur. Millions of furs were traded to Europe and the USA, and the population has not recovered from such decimation. Extensive cullings occurred in Queensland in 1915, 1917 and again in 1919 when over one million Koalas were killed with guns, poison and nooses. The public outcry over the cullings was most likely the first wide-scale environmental issue that rallied Australians.
  • New South Wales - listed at a state scale as vulnerable, but varying regionally from "secure" to "locally extinct".
  • South Australia - classified as Rare.
  • Victoria - The koala population in Victoria is considered "large and thriving".
The US Government have declared the koala a threatened species, however the Australian Government has not. A review of the species national conservation status concluded that the koala are not threatened at a national scale, with a population that numbers in the hundreds of thousands. This was the third review undertaken by the federal government that came to this conclusion. Other studies have estimated as few as 80 000 koalas left in the wild, and the Australian Koala Foundation estimates there are around 100,000. The IUCN lists the species as "Lower Risk / Near Threatened".
koala in Arabic: كوالا
koala in Bulgarian: Коала
koala in Bengali: কোয়ালা
koala in Bosnian: Koala
koala in Catalan: Coala
koala in Czech: Koala medvídkovitý
koala in Welsh: Coala
koala in Danish: Koala
koala in German: Koala
koala in Modern Greek (1453-): Κοάλα
koala in Esperanto: Koalo
koala in Spanish: Phascolarctos cinereus
koala in Persian: کوآلا
koala in Finnish: Koala
koala in French: Koala
koala in Scottish Gaelic: Mathan coala
koala in Galician: Koala
koala in Hebrew: קואלה
koala in Croatian: Koala
koala in Hungarian: Koala
koala in Indonesian: Koala
koala in Ido: Koalo
koala in Icelandic: Pokabjörn
koala in Italian: Phascolarctos cinereus
koala in Japanese: コアラ
koala in Korean: 코알라
koala in Latin: Phascolarctos cinereus
koala in Lithuanian: Koala
koala in Macedonian: Коала
koala in Dutch: Koala
koala in Norwegian Nynorsk: Koala
koala in Norwegian: Koala
koala in Occitan (post 1500): Phascolarctos cinereus
koala in Polish: Koala
koala in Portuguese: Coala
koala in Romanian: Koala
koala in Russian: Коала
koala in Simple English: Koala
koala in Slovenian: Koala
koala in Serbian: Коала
koala in Sundanese: Koala
koala in Swedish: Koala
koala in Tamil: கோவாலா
koala in Thai: โคอาลา
koala in Turkish: Koala
koala in Ukrainian: Коала
koala in Vietnamese: Koala
koala in Chinese: 树熊
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