Thursday, August 16, 2012

Creature Feature: Opossum.

Well, this is unusual. I actually have the motivation to write an entry on a Thursday night. Unfortunately, I just so happened to encounter two of today's animal as barely-recognizable pieces of roadkill. It's a shame; opossums are really quite interesting creatures that many readers can find in their own backyards.

Opossums are the only North American marsupials. They are omnivores and scavengers (that explains the roadkill!), so they are pretty well-adapted to human presence. They've been around since the Cretaceous; chalk 'em up as another mammal likely to survive in a man-made wasteland. If you live in North or South America, there's a good chance you can find an opossum near you. There is even one so cool that it'll get its own entry later, so we're going to focus on the Virginia opossum (Didelphis virginiana) for now.

Opossums look like giant rats at first glance. Despite all similarities, however, opossums are not even remotely related to rats. No, these things have some of the most diverse teeth of any mammals, and they will very kindly show you that they are not rats as soon as you piss them off. Those teeth say a lot.

THIS is car trouble!

There are a number of interesting things about opossum reproduction. They have a split penis and a split vagina- the latter of which led to the family name "Didelphidae." There is a placenta inside of a female opossum, but it is largely non-functional. They have a lot of young; not many of them survive. Since these are marsupials we're talking about, some of them don't even survive to make it to mom's pouch. The surviving babies learn to hitch a ride on on mommy possum's back. Kinda cute!

Opossums are known for an extremely authentic method of playing dead ("playing 'possum"). When a predator approaches, the opossum goes completely limp. As if the lack of movement, even when handled, was not enough to deter most predators, the opossum also starts foaming at the mouth, closes its eyes, and emits a nasty smell from special glands near its rear. Just about the only way to know whether a possum is really dead or not is to see its blood.

On a strange note, the name "opossum" does not come from Latin at all; the similarity to the verb "possum" is purely coincidental. Instead, it comes from a Native American word meaning "white beast." Considering how strange such a common creature is, there is really no better name. What would you call it?

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