Owls Aren't Wise and Bats Aren't Blind (13 page)

Possums are nocturnal, and the mother travels widely on her nightly feeding expeditions. Meanwhile, the babies go with her, riding in her pouch for about three months. This is an extremely useful evolutionary adaptation, for the mother never has to worry about returning to a den to feed her young. As a result, she can range far and wide in search of food, denning here and there for a rest as the spirit moves her.

After this three-month interval, the young possums emerge from the pouch and for a few days remain in a den while the mother forages. Thereafter, the babies resume traveling with their mother. Possum babies are often portrayed dangling from the mother’s tail by their own, but, although it makes an appealing picture, this is just another myth. In real life they either scurry along beside their mother or cling to her long fur.

In just a few more weeks the young possums are grown and set out on their own. After several additional weeks they’ll produce another generation of possums, thereby ensuring that this unusual creature will survive, despite predators and an abnormally brief life span.

8

Like Knights of Old: The Nine-banded Armadillo

MYTHS

The armadillo’s main defense is to curl into a tight ball.

Armadillos feed heavily on the eggs of quail, turkeys, and chickens.

MEDIEVAL ARMORERS THOUGHT THEMSELVES VERY CLEVER WHEN THEY DEVELOPED A METAL CASING OF FLEXIBLE PLATES FOR MOUNTED KNIGHTS, WHO THEN WENT ABOUT SLAYING DRAGONS, RESCUING FAIR DAMSELS IN DISTRESS, AND HAPPILY DISPATCHING EACH OTHER WITH LANCE, BATTLE-AX, AND MACE. However, armadillos and their ancestors perfected a nearly identical, and far more practical, system millions of years before; they had no need to depend on armorers, for they simply grew their own armor! Indeed, the name
armadillo,
a gift from Spanish explorers and conquistadors, means “little armored one”—a good name for this odd and intriguing little creature.

Most species of armadillo are tropical or subtropical, but the nine-banded armadillo
(Dasypus novemcinctus)
has gradually migrated northward through Mexico and into the United States. It now inhabits Louisiana, most of Texas, much of Oklahoma and Arkansas, and parts of Kansas, Missouri, Mississippi, Alabama, Georgia, and Florida.

Our North American armadillo is roughly the size of a house cat. The head and body combined are about sixteen inches long, while the slender, pointed tail is an inch or two shorter. Adult females weigh from eight to thirteen pounds, while the slightly larger males can reach seventeen pounds.

As its species name
novemcinctus
(from Latin
novem,
nine, and
cinctus,
that which girds) indicates, our North American armadillo has nine plates, or bands, sandwiched between a large front plate and a large rear one. These narrow middle plates allow the armadillo to be quite flexible, a quality it would be totally lacking if it had only two or three large plates. The head and tail are also armor-plated, as are the legs. Only the underside lacks protection.

Nine-banded armadillo

It’s commonly thought that this strange little animal’s first line of defense is to curl into a tight, armored ball in order to protect its soft underside. However, the armadillo much prefers to run into brush so thick that its enemies can’t follow, dive down a burrow, dig its way swiftly out of sight, or even escape by swimming. Only as a last resort does it curl into an armored ball, from whence it can kick an attacker with powerful hind legs and long, strong claws.

Although an armadillo’s tough, horny plates do serve
in extremis
as a defense against predators, they probably function more as a shield against thorns, spines, and sharp twigs. The armadillo mostly inhabits areas where sharp, spiny plants seem to be the rule, and its armor enables the little creature to escape danger by scurrying with impunity into thick, thorny brush too daunting for most predators to tackle.

One of the armadillo’s characteristics, however, represents a distinct defensive disadvantage in the modern world: when startled by the sudden approach of something like a speeding auto, the armadillo tends to leap into the air to about bumper height. There, despite the little animal’s armor, the car always wins!

The subject of road-killed armadillos leads to the story of a classic practical joke. A former colleague of mine, driving back to his home in the Midwest from a conference in Texas, picked up a number of freshly killed armadillos along the highway. Then, when he was well north of the armadillo’s range, he began to surreptitiously drop his defunct passengers at strategic points along the highway where they would be highly visible. As a result, great excitement and puzzlement ensued among wildlife officials and the news media in several states because of what seemed a sudden, unexplained incursion of the little armored ones! As far as I know, the perpetrator of this brilliant deception never told anyone but his fellow workers about it.

Armadillos, along with anteaters and sloths, belong to the order Edentata, which means “without teeth.” Although some members of this order, such as the anteater, are literally toothless, the armadillo does have twenty-eight to thirty-two (usually thirty-two) very primitive teeth, in the form of simple pegs. Not surprisingly, then, its omnivorous eating habits concentrate on foods that require little chewing. Worms, insects, grubs, and other small invertebrates make up a large part of the armadillo’s diet. It also has a long, sticky tongue, somewhat like an anteater’s, which is handy for dredging up ants and termites. Soft fruits, berries, birds’ eggs, and carrion also find their way down the armadillo’s rather unfussy gullet.

Because so much of the armadillo’s food comes from grubs, worms, ants, and other subterranean invertebrates, the right kind of soil is a critical factor in armadillo habitat. Soft soil will support a denser population of armadillos than harder soil, and if the soil in an area is excessively hard, armadillos won’t live there.

In some areas of the United States and Mexico, armadillos are regarded as a serious threat to the nests of quail, turkeys, and chickens. This appears to be a bum rap that isn’t supported by the evidence. One study, for example, found the remains of eggs in only five of 281 armadillo stomachs. It appears likely that armadillos are simply being blamed for the depredations of other creatures.

As already noted, the armadillo is a master digger. If the ground is reasonably soft, it can dig its way out of sight in a just a minute or so. This remarkable aptitude for speedy excavation is due to the armadillo’s feet, which are admirably equipped for the task. The middle toes—two of the four on the front feet and three of the five on the rear feet—are the longest and are tipped with formidable claws.

Because armadillos have only a few vestigial hairs on their bodies, they are not well insulated against either heat or cold. When the weather is hot, armadillos are mostly active from evening until dawn; in cold weather, they’re mainly active during the warmest part of the afternoon, and they can’t survive in areas subject to prolonged spells of subfreezing weather.

When the weather is either too cold or too hot, armadillos spend much of their time in dens. These are mostly burrows in the ground as much as fifteen feet long, although they also use dens in the rocks. Great diggers that they are, armadillos usually have numerous burrows. In hot, dry country, they often congregate around streams and water holes, where they take cooling mud baths.

A suit of armor is by no means the armadillo’s only unusual feature. This oddity among mammals is full of surprises, and its reproductive style is every bit as bizarre as its outward appearance. For openers, armadillo copulation itself is decidedly different from that of most mammals. Although the creature’s nine middle plates give it a good deal of flexibility, it isn’t sufficient for the standard “mount from the rear” approach. As an added complication, its genitals are located underneath. Undaunted, armadillos surmount this obstacle with ease by having the female turn on her back during mating.

The armadillo’s aberrant traits continue after breeding. Mating mostly occurs in July, but the fertilized egg from a July mating doesn’t attach to the uterus until November. This phenomenon, known as
delayed implantation,
also occurs in members of the weasel family and among bears (for a detailed description of its advantages, see chapter 14), but it’s far from the mammalian norm.

But wait—the reproductive ways of the armadillo become even more bizarre! The single fertilized egg divides into four embryos; after implantation, these share the same placenta and grow into identical quadruplets of the same sex. Thus an armadillo always bears either four male or four female young. Following a gestation of about 120 days after implantation, these are usually born in March in a burrow with an enlarged chamber. This chamber, which serves as both birthing room and nursery, is filled with soft plant material such as grass and leaves.

The baby armadillos look exactly like miniature adults. They can walk after only a few hours and begin to follow their mother on her rounds in just a few weeks. Although they nurse for only about two months, they continue to stay with their mother for a few additional weeks before going off to live on their own. They’ll be mature by the next summer and will breed at that time.

Armadillo oddities seem to have no end. Consider the creature’s behavior when it encounters a stream. Although, as might be expected, an armadillo lacks buoyancy because of its armor, one can hold its breath for up to six minutes—an adaptation that evidently helps it avoid inhaling dirt and dust while digging burrows. When an armadillo comes to a stream that isn’t excessively wide, it simply wades in and walks along the bottom to the far side. But what of wider waterways? That’s no problem: the versatile armadillo just sucks in air and inflates its digestive tract. Then, with this extra buoyancy, it swims across with ease. Medieval knights in full armor undoubtedly fared far worse than this resourceful little creature when they were pitched off their chargers into deep water!

Both medieval knights and Spanish conquistadors no doubt boasted of their distinguished ancestry, but armadillos can claim a vastly longer lineage. The earliest known ancestors of today’s armadillos date back some 55 million years—only about 10 million years after the demise of the dinosaurs. In time, quite a diverse array of armadillos and their close relatives evolved, some of them quite astonishing.

For example, within the past million years, during the Pleistocene Epoch, there was an enormous armadillo called
Chlamytherium.
This great creature, which was herbivorous, had the bulk of a rhinoceros. Far more recently the so-called giant armadillo
(Holmesina septrionalis)
inhabited Florida. Although far smaller than
Chlamytherium,
this armadillo was nonetheless huge compared with our present-day specimens, for it was six feet long and weighed an estimated six hundred pounds. There were humans in Florida by eleven thousand years ago, and the giant armadillo survived for at least another twelve hundred years, so early humans must have actually encountered this hulking fellow.

Perhaps even more fascinating than these ancient armadillos is a branch of their family tree known as
glyptodonts.
Also known as “turtle armadillos” because of their superficial resemblance to turtles, glyptodonts had a carapace, or single large plate, that covered their entire upper side, making them just as inflexible as turtles. In turtle fashion, they also could retract head and neck inside the protective shell.

One of these glyptodonts was truly gigantic: it was fourteen feet long and towered an astounding fifteen feet high! Despite its vast bulk, however, this perhaps wasn’t the most bizarre of the glyptodonts. That prize probably belongs to the creature known as
Doedicurus.

Doedicurus
must have presented an amazing sight. Along with its inflexible shell, it had a long, stout tail that tapered outward and terminated in a large, spiked ball. No doubt this creature lashed its enemies with this potent weapon, much as knights of yore clobbered each other with maces!

Present-day armadillos are valued for their meat in many areas, although they probably aren’t as widely hunted now as they were in the past. I once had the opportunity to try armadillo meat at a dinner in Texas; it was delicious, tender and moist, with a flavor similar to that of pork. The hides are also used to make a variety of items for sale, mostly in the tourist trade.