Koala

Category: Wildlife

Though often mistakenly called a koala ‘bear’, koalas are marsupials and have no relation to true bears. We want to think of them as cuddly and sweet, but their fur is more akin to sheep’s wool than a teddy bear and their disposition discourages the idea of cuddling. Although there is a popular belief that koalas sleep for such extended periods of time because they are drunk or even high from the toxic leaves of the eucalyptus, there is no truth to that. They do, however, smell a bit like cough drops due to their diet. The first written records of koalas did not appear until the late 18th century, although the Aboriginal people of Australia were well acquainted with the shy and elusive animal.

Koala

Koala

Scientific & Common Names

Kingdom – Animalia

Phylum – Chordata

Class – Mammalia

Infraclass – Marsupialia

Order – Diprotodontia

Suborder – Vombatiformes

Family - Phascolarctidae

Genus – Phascolarctos

Species – Cinereus

Common Names – Koala, koala bear, native bear

Characteristics

Found in western Australia, koalas are almost exclusively arboreal and only take to the ground when they need to move to a new tree. Their stout, rounded bodies have small tails and a curved spine that allows them to live quite comfortably in the crooks of the eucalyptus trees. They have rough pads and two opposing thumbs as well as sharp claws, another adaptation for arboreal life. The adaptation for living in trees has gone so far as to add extra padding on the hindquarters for sitting in the crooks all day and losing two sets of ribs to allow the torso to curve even further. They average about two feet and twenty pounds and, although the color most associated with them is a silvery grey, they can also be brown. Koalas mature at the age of two and they can live twenty years, although they live about twelve in the wild. They have rounded, fuzzy ears and a large, flat black nose that dominates their facial features.

Breeding

Koalas are solitary and territorial and mating is one of the few times they will tolerate the presence of another. Being marsupials, the gestation period is very short – only 35 days. Like kangaroos, koalas have pouches, but their pouches face backward due to their ancient history of being burrowers. The backward pouch kept dirt from entering and a strong muscle at the entrance kept the baby (joey) secure. The joey, about the size of a bean when born, will crawl into the pouch on its own and remain there, nursing, for six months. The mother provides the bacteria necessary for her offspring to digest eucalyptus in a substance called ‘pap’, which the joey will consume before leaving the pouch. The youngster will remain with its mother – riding her back when it becomes too large for the pouch – for another six months before going on its own mostly solitary journey.

Behavior

Koalas are solitary and nocturnal, spending only a few hours each day in eating, grooming, or other activities. Their exclusively eucalyptus diet is difficult to digest and poor in nutrition, so koalas eat a tremendous amount and then spend up to twenty hours a day sleeping and digesting. Of the over 600 species of eucalyptus, all are toxic but some more than others. Koalas eat only the least toxic and they have a specifically designed intestinal tract along with specialized bacteria that allows them to consume it without being harmed.

History

The family Phascolarctidae now has only species, the koala, with the former species all extinct, including marsupial lions and tapirs. Koalas appeared 40 million years ago during the Eocene period and there have been several species, some of which lived in rainforests, but only P. cinereus survived to modern times.

Present Status

Although koalas themselves are protected and listed as threatened, their numbers are dropping due to habitat loss and there may be fewer than 8,000 koalas left in the wild. After extensive hunting in the early twentieth century, there was an effort to protect and reintroduce the iconic animal. Without habitat protection, however, those efforts could prove to be in vain. Most koalas do have chlamydia but this rarely has a negative impact on them unless they are stressed or weak.

References

  1. The Koala: Natural History, Conservation and Management by Roger Martin, Kathrine Handasyde
  2. Koala: Origins of an Icon by Stephen Jackson
  3. Koala: An Historical Biography (Australian Natural History Series) by Ann Moyal
  4. Wildlife of Australia (Princeton Pocket Guides) by Sam Woods
  5. The Eucalyptus: A Natural and Commercial History of the Gum Tree (Center Books in Natural History) by Professor Robin W. Doughty