Thursday, May 17, 2012

Other than cool accents, what do Koalas (Phascolarctos cinereus) and Virginia Opossums (Didelphis virginiana) have in common?

Koalas – our endangered species of the week - and possums are both marsupials (photo from worldsmostamazingthings.com)!  Virginia opossums are the only marsupials in North America, and koalas are only found in Australia.  Who doesn’t love koalas, the tree-climbing spokes-mammal of Quantas Airlines?  Adult koalas eat eucalyptus leaves and have a specially evolved intestinal system to be able to harmlessly digest these leaves and the toxins found in them.   Koala size is a perfect example of an ecological rule called Bergmann’s rule  (individuals of a species are bigger in populations that live in cooler climates, usually closer to the poles); southern koalas weigh between 20 and 30 pounds, while northern koalas weigh closer  to 15 pounds. 

Koalas give birth to just one baby, a “joey”, at a time.  When the joey is born after about 35 days of gestation, it is only about the size of a jelly bean.  It makes its way from the birth canal to the mother’s pouch, where it will live and grow for the next 6 months, drinking milk and “pap” , a substance from the mother’s intestines.  Much like tree kangaroos, the nipple of the mother koala actually swells or bonds to the mouth of the baby so that the two cannot be separated while the joey develops.

Koalas spend A LOT of time sleeping – 18-22 hours per day!

During the early 1900s, koalas were overhunted for their fur.  Today, koalas are considered threatened under the U.S. Endangered Species Act throughout their range.  Current threats include loss of habitat due to development, car collisions, dog attacks, and disease.  If you’re interested in learning more about koalas, there’s a terrific article in the May 2012 issue of National Geographic Magazine, or in Wildlife Heroes by Scardina and Flocken.

So, koalas are cute and have fascinating evolutionary adaptations – but why should we really care about koala preservation?  According to Wildlife Heroes, “The koala is the symbol of Australia.  It is estimated to be contributing between $1.1 and $2.5 billion dollars annually to Australia’s economy through koala-linked tourism, koala-viewing industry revenue, and purchases of “koalabilia,” which translates into 9,000 jobs for Australians.”  As stated by Deborah Tabart in the same book, “If you cannot save the koala, who does not destroy crops, does not destroy livestock, does not attack – just sits beautifully in a gum tree – then it will be impossible to save any of our nature.  If there is not enough will to save an animal as beloved and harmless as the koala, how can we even begin to address conservation needs for animals like lions and elephants that come into conflict with humans regularly?”

Want to help koala conservation?  Check out the Australia Koala Foundation, the Sunshine Coast Koala Wildlife Rescue, or the Australia Zoo Wildlife Hospital.

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