Naturespeak A naturalist's view of the world

December 18, 2008

Possum Trot

Filed under: Uncategorized — wykes @ 2:23 pm

As evidence that opossums can push the envelope every now and then, I present this picture. It would be inaccurate to say that this individual was speeding, but it was “moving rapidly forward.” It guess you could say it was trotting. The blur factor gives the image a NASCAR type look. The fleeing beast was dashing for the finish line, and the cover of the brush line, just as the picture was snapped.

This speedster was the second such opossum that I encountered in so many weeks. Last week, another one crossed the road in front of me (yes, they actually can successfully cross the road on occasion) and did so at a brisk pace. Watching that one, and the one pictured above, I have gained a new respect for ‘possum trotting skills. These animals, plantigrade or flat-footed walkers that they are, engage in a determined form of speed walking. Head down and tail held straight out, they burn up ground at the rate of approximately 4.5 mph.

All of this got me to wondering what you should call this style of movement. It certainly isn’t running and I’m not sure trotting is the correct term. Several southern states have a town named Possum Trot, but that doesn’t make it right. So, I hit the references and Internet for answers and came up with the usual mix of tripe and truth. For instance, one site claims that 8.3 million opossums are killed on our roads every year – in essence proving the claim that they can’t run and are born dead on the road! Another one classifies them as rodents and puts them in the company of “mice, rats, and raccoons.” They are marsupials, by the way, and raccoons are in the weasel family.  I also found out that there is actually an organisation called the Opossum Society of North America. I wonder if they have 8 million members? Anyway, one site did put out the 4.5 mph figure based on a reference from McManus (1970), but didn’t commit to the running question.

Finally, the Royal Veterinary College in England came up with the answer. They were working on elephants. “Elephants can’t technically run,” they said ,” but they do walk fast.” Pachyderms have been clocked at over 15 mph. The usual definition of running implies that at one point all four feet need to be off the ground. In other words, there is an aerial stage. Elephants always have at least one foot on the ground when moving fast and can “bounce.”

The scientists explained this question of “bouncing” in detail but essentially said that motivating with bent knees creates a “bounce” movement that aides kinetic energy transfer. They, in fact, gave this type of movement the name of “Groucho Running.”  I quote their definition that this “unusual form of running gait often lacks an aerial phase. It is known among many animals with more than four legs, as well as some four-legged animals such as lizards, sheep, opossums, and others and bipeds such as birds at medium speed and comedic humans.”

So, there you have it. Opossums, like elephants,  are Groucho Runners. That may be “the most ridiculous thing you ever hoid,” but it is documented science.

No Comments »

No comments yet.

RSS feed for comments on this post. TrackBack URL

Leave a comment

Powered by WordPress