Family: Phascolarctidae
Females are usually slightly smaller and slightly less heavy than males
This difference in size is most likely an adaptation for the colder climate in the south
Physical Features: Although commonly called bears, koalas are actually marsupials — an infraclass of mammals best known for their pouches
Immediately after birth, the underdeveloped newborns migrate into these pouches or marsupials, where they will continue to feed and grow for the next several months
Many marsupials have pouches that open upwards towards their heads, but a koala’s pouch opens towards their hind legs
Koalas are arboreal (tree-dwelling) marsupials and have a number of adaptations that are useful for living in trees
Their bodies are slender with long, muscular fore and hind limbs and large, sharp claws that help grip tree trunks, and rough skin on the bottom of their feet that provides friction good for climbing
The koala has five toes on its front paws, two of which are opposite (it would be like a human having two thumbs)
This evolutionary adaptation allows the koala to cling to branches as it moves from tree to tree
Its hind paws have one opposable toe without a claw, again for grasping, and the second and third toes are fused into a single double claw that the animal uses for grooming purposes
Lifespan: Koalas generally live an average of 13-17 years, with females often living longer than males, whose life expectancy is often less than 10 years due to injuries from fights, dog attacks and being hit by cars
Diet: Koalas are folivores (leaf eaters) and feed primarily on eucalyptus leaves, although they will occasionally eat non-eucalyptus plant species
They eat about half a kilogram of leaves a day and rarely drink, and they get water from leafy food
Although there are more than 600 species of eucalyptus, koalas often eat only a few species of eucalyptus, often specific to the region
Eucalyptus leaves are highly toxic to most mammals, but koalas have a digestive system specially adapted to detoxify the toxic chemicals in the leaves
They are the only known mammals other than the great glider and the ring-tailed possum that live on a diet of eucalyptus
Due to the high consumption of energy needed to digest their food, which is rich in fiber, poor in nutrients, and also toxic to most animals, and the low metabolic rate of the species, koalas spend 18 to 20 hours a day sleeping
Geography: Koalas are native to Australia and are found in the eastern and southern parts of the country
Habitat: The species lives in tall eucalyptus forests, low eucalyptus forests, as well as coastal and island forests
Breeding and social structure: Koalas are mostly solitary animals and live in well-defined home ranges
Each home is often controlled by a single alpha male, with a number of females also living within the area These females will mate almost exclusively with the dominant male, who will defend his territory against outside males who might move into the area
Females generally want to breed with the largest male and rely on the male’s vocalizations to gauge the size of a potential mate
Although habitats may overlap, koalas are mostly solitary animals that avoid conflict and interaction whenever possible
Males are generally louder than females, but females will communicate loudly with their young, and both sexes make different sounds when in distress
A joey is born blind, furless, earless and only one inch long
Immediately after birth, they crawl from the birth canal into the mother’s pouch
There, the joey attaches itself to one of the two teats and will not leave the pouch for approximately six months
After six to seven months of exclusive milk feeding, Joey begins to eat his mother’s protein-rich porridge, which inoculates the baby’s gut with the necessary microbes to digest the eucalyptus
At about 12 months, a young koala no longer drinks milk or fits in its mother’s pouch
If the mother mates again, her mature joey will emerge on his own when his younger sibling emerges from outside the pouch
Female koalas do not always reproduce once a year, so in that case a one-year-old koala can stay with its mother for a longer time
Once independent, the joey stays close to its mother’s territory before claiming its own
Koalas become sexually mature around two or three years of age, but non-alpha males are far less likely to mate successfully
However, human activity poses the greatest threat to koala populations
Today, koalas face excessive habitat loss due to urban and agricultural development in the region, forcing them to live in smaller areas and closer to human populations
As many as 4,000 koalas are killed every year by run-over dogs and cars
Isolated populations reproduce, making animals more susceptible to disease,
Chlamydia is common in koalas, but it is more likely to develop into dangerous infections when the animals are vulnerable or stressed
In 1816, the koala was given its scientific name, phascolarctos cinereus, which loosely translates to “ash-gray bag bear”
Koalas are the only members of the Phascolarctidae family
The closest living relative of the koala is the wombat
Fossils of koala-like animals have been found that date back as far as 25 to 40 million years
A koala’s brain is smaller, compared to its body, than that of other marsupials: about 02% of its body weight
In keeping with its low-energy lifestyle, the koala has a lower body temperature than other animals its size: around 979 degrees F (366 C)
For comparison, a healthy temperature for domestic cats and dogs ranges from 100 to 1025 (378 to 392 C)