A friend in the night

Last week’s column began the discussion on the Virginia opossum, friend or foe?  I often receive questions about this particular species and am delighted to clear up a few misconceptions.  Since early spring is the height of opossum breeding season here in southwest Florida (Peace River Wildlife Center took in 47 opossum babies in April of last year alone) it is a great time for everyone to get to know these wonderful little fuzz balls a bit better.

I think of the opossum as a ball of fluff and personality, but what most people see is a mouthful of teeth.  It is true that the Virginia opossum has 50 teeth, the most of any land mammal.  50 needle-sharp pointy little teeth.  North America’s only marsupial is not an aggressive animal, though.  When startled or threatened, it will bare its teeth and snarl.  When that doesn’t scare off the threat, it will promptly fall over and play dead.

Yes, it actually does play ‘possum.  It falls onto its side, its heart rate and breathing slow way down, the body becomes stiff, the tongue hangs out and the eyes remain closed.  A foul smelling excretion is emitted from the anal sacs to further the charade with the smell of death.  Feigning death is often enough to make the opossum less desirable to the predator, who will lose interest and wander off in search of more challenging (and tasty) prey.  An opossum can and will bite if provoked, but it will rarely go out of its way to initiate such an attack.

Although often called a “possum,” it is officially correct to pronounce the “o.”  There is another completely different animal called a possum that hails from Australia and Asia.  A true omnivore, our opossum eats a wide variety of foods—both plants and animals.  It is immune to the rattlesnake’s venom and has been known to snack on them.  It also consumes ticks that spread Lyme disease and other tick-borne illnesses, unaffected by those illnesses as well.  It eats a wide variety of what we consider household pests, from palmetto bugs to mice.  Its tendency to scavenge carcasses often leads to it becoming roadkill itself.  It’s also what leads it to poorly secured trash cans.

The Virginia opossum has many other interesting traits.  The opossum is used widely in medical research on gastrointestinal studies due to the similarity of its GI tract to that of humans.  (But please do not take this as a suggestion to start eating rattlesnakes and roaches.)  It is also used in aging studies because of its short life span, rarely living longer than two years.  It does not get many of the viral diseases that plague other mammals, like rabies and distemper, due to its low body temperature.  It has an opposable toe on both the front and rear feet, similar to our thumbs, that renders it particularly dexterous.  Adding the prehensile tail into the equation, this species is very good at climbing.

But don’t confuse ability with genius.  Brain size is usually thought of as a gauge for intelligence, and the opossum has the smallest brain size per body weight ratio of any mammal.  A similarly sized raccoon has a brain six times larger than the opossum.  In the words of Albert Einstein, if you judge a fish by its ability to climb a tree, it will spend its whole life believing that it is stupid.  Despite this, the opossum has done an amazing job at surviving where other species have struggled.  Originally from South America, the opossum migrated north when Panama formed a land bridge between the two formerly separated continents of North and South America.  Other than the armadillo and porcupine, most of the Southern species did not adjust to life in the north.  The opossum shows an uncanny ability to continue to adapt in ever changing habitats as people encroach on more and more of their territory.

The Virginia opossum does not make a good pet.  It is not affectionate and can be unpredictable.  The young are quite cute and easy to handle for our home-care volunteers, but as the animal ages, it becomes reticent and prefers a solitary lifestyle.  Once mature, it is not a social animal, one of the more endearing qualities that help dogs, cats, horses, ferrets, and other pet fit into our lives.  The opossum can, however, be considered a friend for all of the wonderful services it provides—from pest control around the house, to roadside clean-up, to medical services.  Add that to the list of things you never knew you never knew.  So while you might not find your pet goldfish in a tree, you can find an opossum up there, taking care of the business of being an opossum.

by-Robin Jenkins, DVM

fish climb tree
fish climb tree