Skull no. 7: Virginia opossum

Didelphis virginiana

Didelphis virginiana

Virginia opossum wiki

Virginia opossum have 50 teeth – more than any other North American mammal.

They are surprisingly short-lived for their size; about one to two years in the wild, less than five in captivity.

Opossums are highly resistant to snake venom, ricin, and botulism; they limit the spread of Lyme disease and they’re virtually immune to rabies, presumably due to their low body temperature. 

Opossums are relatively clean animals and love pedicures.

The generic name (Didelphis) is derived from Ancient Greek, meaning “two wombs,” referring to the opossum’s pouch.

Like primates, Virginia opossums have opposable thumbs (which may allow them to hold a pen and write poetry), but their thumbs are on their back feet. They also have a semi-prehensile tail.  They can hang on – if you’ve ever seen a momma with her young, you can attest.

The Virginia opossum has one median nipple, surrounded by twelve others, for a total of thirteen teats (The record number of teats for an animal is the tenrec, which has up to thirty nipples; the record for a human is seven.)

Like all marsupials, their pelts consist only of awn hair, meaning they have no undercoat, nor guard hairs. 

Virginia opossums have one of the lowest brain-to-body-mass ratio of any marsupial.  This, paired with their close-set eyes, makes them arguably the stupidest looking North American mammal.

Opossums are infamous for ‘playing ’possum.’  This reaction, to lay completely inert, is involuntary, like fainting, and is usually a last resort.  For obvious reasons, they try to make themselves inedible at this point by extruding noxious smells and generally appearing to be dead and rotten.  Before they get this far however, they’ll bare their teeth and hiss or growl or, better yet, escape altogether; they’re rarely aggressive and poor fighters at best.

The word ‘opossum’ is borrowed from the Algonquin word for the creature which roughly translates into “white animal” (maybe).  Because the word is Algonquin, and not Latin or Greek, the plural form is opossums, not opossa or opossi. 

Virginia or North American opossum

Since our English is so lazy, we Americans abbreviate that word to possum in speech when we are commonly referring to the Virginia opossum, the only marsupial in North America.  This was the first opossum to be identified by Europeans, and so, the 102 other species (all in South America) are also called ‘opossums.’

Common brushtail possum

The possum hails from Australia, New Zealand, and New Guinea and there are none in the Americas. Since the Algonquin peoples were discovered by Europeans about 160 years before the discovery of the island continent of Australia, a similar animal in that region was named after the North American ’possum.  When the Europeans discovered that the two are taxonomically distinct, the American ’possum was reverted to being called an ‘opossum,’ and the Australian equivalent is ‘possum.’  But I still say ’possum when speaking.  

They’re a strange animal, and I can’t make up my mind whether they look cute, dumb, or gross – they seem to be all three at times.  Plus, they’ve got that rat tail.

Where I Got It:  Since I decided to start collecting skulls, I’ve picked up more than a few dead animals.  My family is sort of used to me stopping suddenly or circling back around to pick up a carcass.  It took me a few tries before I learned that freeway carcasses aren’t worth stopping for; the skulls are almost always broken from the impact(s).  Country highways and rural roads are better.  But the best are found in the woods, off roads, not a victim of an auto collision.  I’ve found deer, squirrels, nutria, raccoons, and cats.  But by far the most animals I see are opossums.  I’ve picked up a few, but I won’t any more; they’re a pain in the ass.  The first opossum skull I had, however, I bought at a little shop called Crafter’s Alley in the virtually abandoned Gateway Mall in Springfield, OR.  This shop is like a miniature flea market.  Presumably crafters (or possibly hoarders) rent space in the shop inside the mall to sell their stuff.  In one corner of the shop, there is a small collection of skulls, as well as other bones, and bugs in shadow boxes or resin.  I found an opossum skull here once, the first skull I bought from this store.  Not until I got it home did I notice that the bottom jaw didn’t fit.  You probably already knew this, but there is a joint in the center of (most?) mandibles, which is usually connected by ligaments, but sometimes grows together, as in humans.  Often ligaments are removed during processing and the bones come apart.  In this case, I had half the mandible from this opossum and half from another, glued together, so the jaw didn’t quite fit right.  My daughter’s 7th grade science teacher has quite a few skulls in his classroom, and I eventually donated that skull to his collection.

This is not that opossum.

Coming home from some family adventure or other, I had just pulled off I5 onto a rural highway when I saw an opossum on the shoulder.  Naturally, the family had become semi-accustomed to my stopping for roadkill, so there was more groaning than curiosity from my passengers.  This little creature was not horribly mangled in any way – it was relatively bloodless and its coat was dirty, but basically intact.  However, it’s tongue lolled out and it had bitten completely through it with its left canine, which was now broken; none of the other teeth were injured, so it seemed as though it had actually bitten through its own tongue, rather than having had its tooth forced through it from the impact.  Having said all that, you never know what can happen in an auto accident.  As you know (see above) ligaments are removed during skull processing, along with everything else but the bone; skin, muscle, cartilage…. This inevitably leads to things falling apart; some or all teeth, nasal bones, jaw bone.   So there’s a little bit of gluing involved; usually there are three to seven pieces to glue together, and some teeth.  This skull fell into fifteen pieces, and the teeth that fell out were incisors, virtually identical in both rows and top and bottom. They took some time to decipher, and I’m still not sure I have them in right. This is typical for opossum skulls processed using maceration, perhaps due to their short lifespans; maybe their skull bones don’t have time to fuse together.

20150509_101311

This skull turned out pretty good.  The background in these pictures is the 12 feet or so of eight inch thick concrete I’d busted up with a jackhammer rented from the Home Depot.  That job gave me a bleeding hemorrhoid, but that’s a story for another time.…

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