Order: Diprotodontia Prev. Marsupialia
Family: Phascolarctidae prev. Phalangeridae
Genus & Species: Phascolarctos cinerus
APPEARANCE
Koalas are small, furry marsupials of Australia that resemble a cross
between a bear and a sloth. In habits they resemble the loris and the sloth.
And yet they carry their underdeveloped young in a pouch, making them
marsupials like the wombat or opossum.
Sexual dimorphism is present in this species, with the males being larger
than the females. They grow to heights of 24-30 in (60-75 cm). The males
weigh 14.3-26 lbs (6.5-11.8 kg) , and the females weigh 11.2-17.4 lbs (5.1-7.9
kg). The koalas in the north are smaller than those in the south.
Koalas are unusual looking mammals. The body is short and stocky, and is
tailless except for a short rounded stump where the tail would be. The ears
are large and tufted, the eyes are small with vertical slits for the pupils, and
the snout is large, prominent, and black. The forelegs are slightly longer
than the hindelegs and the hindelegs are slightly stickier than the forelegs.
All four feet are used for grasping. The forefeet have five digits, with the
first two thumbs opposed to the last three fingers. On the hindefeet, there
are again five toes, with the first one much smaller and opposed to the rest.
The second and third toes are joined together. All the feet end in sharp
claws. Koalas lack canine teeth. The males have a sternal scent gland
located on their stomach, which they use to communicate with other koalas.
Koalas have the thickest coat of all the marsupials. It is ash-grey in colour,
with a brown tinge on the upper quarters. The hindquarters are tawny and
the underparts are white. Koalas in the north have a short coat; koalas in
the south have a longer coat with the backhairs thicker and longer than
those on the belly.
Koalas are distinct from other marsupials in that their pouch opens to the
back, not to the front. It has "drawstring" muscles that, when pulled
taught, will close the pouch.
Koalas are avid tree climbers and use their feet to grasp the branches. They
are very strong swimmers but are awkward on land. They have a life span of
13-18 years in captivity, shorter in the wild.
HABITAT
Koalas are mostly found in eastern Australia, from northern Queensland to
southwestern Victoria. They are extinct in southern Australia, but efforts
are being made to reintroduce them there. They have been introduced to
Flinders Island (S. Australia) and the Phillip and French Islands off
Victoria, as well as western Australia.
Koalas are fussy eaters and therefore are found only in small patches in
eucalyptus forests and woodlands where the vegetation is suitable.
Koalas are tree dwellers, sleeping for 20 h curled in a branch during the day
and eating at night. They live solitary lives, getting together only to mate.
FOOD
Koalas are strictly herbivorous in nature, feeding only on the leaves of 120
out of 600 species of eucalyptus (or gum) trees. They feed primarily on 12
species, including the manna gum and the red gum. They eat roughly 1-2 lbs
of leaves each day, some of which enters cheek pouches to be eaten later. To
cope with this diet, their digestive system is specialized to handle gum
leaves.
Eucalyptus trees produce toxins during some stage of their growth, and
therefore koalas must have a good sense of smell to know which leaves are
edible and which leaves are not.
Koalas will eat soils to gain minerals, and drink very little water as the
leaves they eat provide most of it for them.
ENEMIES
Koalas have few natural enemies, being killed mainly by dingos, domestic
dogs, and cars. When koalas get stressed, they become susceptible to
disease, and large numbers have been wiped out by diseases such as
chlamydia, conjunctivitis, cystitis, and leukemia. Their biggest threat is
man, who at one time nearly hunted them to extinction for sport, and, after
1908, for their coat. By 1824, over 2 million koala pelts had ben exported.
Today, measures are being made to protect koalas, but forest fires and land
clearance still take their toll. There are 40000-80000 koalas left in the wild.
BREEDING
Females reach sexual maturity at 2-3 years, males at 3-4 years. The breeding
season is from September to January in the south and November to
February in the north. 1 young, rarely two, is born after a 35 day gestation
period. It is blind at birth and is 3/4 in (19 mm) long and 0.5 g in weight. It
drags itself into the pouch by following a trail of saliva laid down by the
mother and grabs hold of one of two nipples. After 22 weeks, the eyes open
and the Joey looks out of the pouch. By 24 weeks it is fully furred. At 36
weeks it emerges from the pouch and clings to its mother's back until 48
weeks, when it becomes adventurous and leaves its mother for short periods
of time. It goes off on its own after 1 year.
RELATIVES
There are 3 subspecies of the koala: P. c. victor, P. c. cinerus, and P. c.
adustus.
RESOURCES CITED
1. "Koala" Funk & Wagnall's Wildlife Encyclopedia, pg 1215, vol 10, 1974,
USA, BPC Pub Ltd
2. "Koala" Wildlife Fact File, USA, IM Pub
3. www2.jps.net/~jpeng/Koala/koala.html
4. www.akfkoala.gil.com.au/kidfacts.html
5. www.onthenet.com.au/~jbergh/koala5.htm
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