—This article by Jerry Cates, first published on 14 March 2010, was last revised on 25 December 2016. © Bugsinthenews Vol. 11:03(15).
At a relatively large retirement and nursing facility in Temple, Texas, the number of Virginia Opossums observed during 2010 increased considerably over similar observations in previous years. Possibly a lack of food, in the normal foraging range of these animals, was to blame. The maintenance staff at that nursing and retirement facility trapped and relocated a large number of opossums that year, without making a serious dent in the number of such animals that were being observed.
That is not surprising. In most locales in Texas, opossums are present in relatively large numbers. Further, they are solitary, nomadic, transient foragers and nesters. They forage for food over a fairly wide expanse of land, establishing a territory that the animal divides into a series of foraging sectors. Each sector contains at least one nest that the opossum uses for the several days it is foraging in that sector, before the animal moves on to another sector, and a different nest, within its established territory.
This general pattern of foraging and nesting is common among nearly all wild animals found in Texas. However, unlike other wild animals, the opossum’s foraging behavior is not markedly affected by seasonal additions of litters of young. For other animals, the young must be confined to the animal’s nest until weaned and able to ambulate and forage on their own, first with their mother, then alone. Not so with the Virginia opossum (Didelphis virginiana), the only marsupial found in North America north of Mexico, as the mother is able to carry her babies in her marsupium on foraging expeditions.
The female Virginia opossum, which may have as many as three litters a year, breeds from late December through early October of the following year; most young are born between February and June. The female has an estrous cycle of about 28 days, and often gives birth to a large number of young, known as joeys, at a time. The birth litter generally numbers 20-30, but can be up to 50 at a time. Young are born 12-14 days after mating. Once born, the newly birthed joeys have to find their way to the mother’s marsupium and attach to a teat. Many do not survive that trek, but of those that do, only as many as 13 can do so and attach to the mother’s teats, as the female has but 13 such teats, arranged in a circle of 12, with a single teat — the 13th — in the center, and no more than one joey can attach to a given teat. Though as many as 13 joeys can survive, the average suckling litter numbers eight or nine joeys.
Suckling young reside in the marsupial pouch for about two and a half months before leaving the pouch and climbing onto the mother’s back. There they hang on for the ride as their mother forages, hikes her territory, and nests, for another two to three months.
In any case, the specimen shown above at left was trapped in Temple, Texas, on 9 March 2010. This animal measured about 16 inches from its snout to (but not including) its scaly tail and weighed about 10 lbs. Thus, it was a medium-sized opossum, at least in comparison with others being found in the same general area in recent days.
Note that the body is covered with a dense, coarse fur that is pale gray or white over the main portion of the body. A dark gray, almost black mantle falls over the shoulders, reaching to the posterior edge of the top of the head. This acquires its color from sparse, but dark, hairs that are longer than the short gray, pale white hairs underneath. The legs and upper paws, by contrast, are coated with short, dark to black hairs, as is the area immediately surrounding each eye. The articulating appendages of each paw are essentially hairless, as is the prehensile tail. One can, from this appearance, understand why the Algonquin Indians referred to its forebears as “Wa-PAWTH-um-wa,” or White Animal. It is from this Algonquinian word that the opossum got its name.
The long snout of the Virginia opossum is very noticeable, and sets the animal off from the other mammals that share its range. So, also, are the upper and lower canine teeth in the animal’s mouth. The latter are followed, in the upper and lower jaw, by molars used for grinding and masticating. The Virginia opossum has fifty teeth in total, more than the number of teeth found in any other mammal.
If threatened by a large animal or man, the Virginia opossum hisses and growls, while opening its mouth in a wide gape, and baring a set of long, sharp, canine teeth. The gesture is intended to frighten accosting animals into breaking off their attack. If the accosting party retreats not, but instead makes contact, the opossum’s defensive maneuver escalates to actual biting, but with a muted ferocity wholly unable to cause serious injury. Should the attacker persist, and cause injury to the opossum, the latter submits by breaking off its feigned defense, adopting a passive stance that culminates in a real, unfeigned, comatose state known in animal lore as “playing possum”. Therein, the opossum appears as though dead, its “lifeless” eyes open, its limp tongue hanging out, body unmoving, and an offensive-smelling fluid draining from its anus.
Ah, but let us now speak of this opossum as one very much alive. Gander at its tail, for starters. And note that it appears as one might expect a rat’s tail, hairless, scaly, a rather loathsome sight. Some even suppose, because of this fraudulent bit of evidence, that rats and opossums share a common lineage. They would be wrong.
Not only is the opossum tail nothing like that of a rat by way of blood, but neither by way of function. No rat can loop its tail around an object and thereby carry said object wherever it wishes. The opossum tail is prehensile (Latin prehensus, “to grasp, seize”); that is, the thing is adapted for grasping and taking hold of by wrapping about that which is to be grasped. We speak of a prehensile mind, meaning one that is unusually precocious, able to comprehend complex ideas with a minimum of input and effort, and so the opossum’s tail, while to the uninitiated quite ugly, is to the zoologist a marvel of anatomical engineering. But not just the tail of the opossum is a thing of wonder…
The front paws of the opossum are remarkably like the forward hands of primates. At least in outward appearance. The fifth finger, or thumb, of the front paw is slightly opposed to the first four fingers, enabling the opossum use its front paws to grasp objects readily.
The rear paws are even more interesting. They are specially adapted to grasping, even moreso than the front paws. All four “toes” are fitted with long claws, but the fifth toe, which is fully opposable to the other four, has no claw at all. This absence of a nail, far from “throwing the horse,” enables the animal to make full use of the posterior paw’s ability to grasp limbs, holding it steady while aloft collecting fruit still hanging in the tree. Like persimmons, its favorite fruit…
With the advent of “civilized” man, the purity of the opossum’s existence became twisted. Now it chooses, more often than not, to live a life twixt commensality and wilderness. Securing food from man’s trash is much easier than living off the “fat” of the untamed wild. So, by night, it raids our offal pails, risking life and limb in the process by slinking much too close to our dogs and cats, which often take sport in driving it into a coma. Opossums in the wild rarely live more than two years. In captivity, they may live to four years, but not much beyond.
Opossums and ectoparasites
The author has examined a number of opossums, adult and juvenile, in the wild. In a majority of cases the animals were found to be infested with a number of ectoparasites, including most particularly fleas, ticks, and mites. It is commonly believed that because these animals groom themselves thoroughly, much as do common house cats, they not only rid their own bodies of ticks, but — owing to their tendency to attract ticks to their bodies while foraging — are efficient magnets for such parasites. Because they then groom the ticks from their fur and swallow them, they are able to rid yards of ticks and thus protect their foraging areas from ticks that carry Lyme disease.
No doubt the presence of opossums can have a negative effect on the tick population within their foraging territories. However, this investigator has personally witnessed a number of instances where the presence of opossum nests, near or under homes, was associated with an otherwise unexplained observance of mites and ticks inside those homes.
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