Koala is a thickset arboreal marsupial herbivore

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awais
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Koala is a thickset arboreal marsupial herbivore

Post by awais » May 07, 2009 Views: 8703

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.



The word koala comes from the 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".



The scientific name of the Koala's genus, Phascolarctos, is
derived from Greek phaskolos "pouch" and arktos "bear". Its species name, cinereus, is Latin and means "ash-coloured".



Although the Koala is not a bear, when first adopted by English
speakers, the name Koala bear became popular, as this roughly
evoked the species' similarity in appearance to the Teddy bear,
to people unfamiliar with it. Although taxonomically incorrect, the
name Koala bear is still in use today outside Australia — its use
is discouraged because of the inaccuracy in the name. 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 12 kg (26 lb) for males and 8.5 kg (19 lb) for females.
In tropical and sub-tropical Queensland, however, the Koala is
smaller (at around 6.5 kg (14 lb) for an average male and just
over 5 kg (11 lb) 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.



Diet and behaviour


he 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.[21]



Handling of Koalas has been a source of political contention due
to these risks, which can 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
500 g (18 oz) 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: while young are
being weaned, the mother passes these essential digestive aids on
to her offspring.





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