10 Surprising Facts About Armadillos

How Much Do You Know About These Animals?

Armadillos are among the most distinctive-looking of all mammals. They look a bit like a cross between a polecat and an armored dinosaur. While armadillos are common sights in certain parts of North, Central, and South America, they remain objects of intense curiosity—and for good reason. Check out the following list of 10 of their most interesting features and habits.

01
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There Are 21 Identified Armadillo Species

Nine-banded armadillo

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The nine-banded armadillo, Dasypus novemcinctus, is by far the most familiar, but armadillos come in an impressive range of shapes and sizes, and with some of the most amusing names. Among the less-well-known species are the screaming hairy armadillo, the greater long-nosed armadillo, the southern naked-tailed armadillo, the pink fairy armadillo (which is only about the size of a squirrel), and the giant armadillo (120 pounds—a good match for a welterweight fighter). All of these armadillo species are characterized by the armor plating on their heads, backs, and tails—the distinctive feature that gives this family of mammals its name (Spanish for "little armored ones").

02
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Armadillos Live in North, Central, and South America

yellow armadillo from brazil

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Armadillos are exclusively New World mammals, originating in South America millions of years ago during the Cenozoic Era, when the Central American isthmus had yet to form and this continent was cut off from North America. Starting about three million years ago, the appearance of the isthmus facilitated the Great American Interchange, when various armadillo species migrated north (and, in turn, other types of mammals migrated south and replaced the native South American fauna). Today, most armadillos live exclusively in Central or South America. The only species that ranges across the expanse of the Americas is the nine-banded armadillo, which can be found as far afield as Texas, Florida, and Missouri.

03
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The Plates of Armadillos Are Made of Bone

A model cross-section of an armadillo skeleton
Wikimedia Commons

Unlike the horns of rhinos or the fingernails and toenails of humans, the plates of armadillos are made of solid bone. They grow directly out of these animals' vertebrae. The number and pattern of the bands range anywhere from three to nine, depending on the species. Given this anatomical fact, there is actually only one armadillo species—the three-banded armadillo—that's flexible enough to curl up into an impenetrable ball when threatened. Other armadillos are too unwieldy to pull off this trick and prefer to escape predators by simply running away or, like the nine-banded armadillo, executing a sudden vertical leap three or four feet into the air.

04
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Armadillos Feed Exclusively on Invertebrates

A close-up of an armadillo ready to dig for food with is long claws

Ben Cranke / Getty Images

The vast majority of armored animals—from the long-extinct Ankylosaurus to the modern pangolin—evolved, so their plates were not for intimidating other creatures but to avoid being eaten by predators. Such is the case with armadillos, which subsist exclusively on ants, termites, worms, grubs, and pretty much any other invertebrates that can be unearthed by burrowing into the soil. On the other end of the food chain, smaller armadillo species are preyed on by coyotes, cougars, and bobcats, and occasionally even hawks and eagles. Part of the reason nine-banded armadillos are so widespread is that they're not especially favored by natural predators. In fact, most nine-banders are killed by humans, either on purpose (for their meat) or accidentally (by speeding cars).

05
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Armadillos Are Closely Related to Sloths and Anteaters

An Anteater in a zoo
Both anteaters and armadillos are classified as xenarthrans.

Long Zhiyong / Getty Images

Armadillos are classified as xenarthrans, a superorder of placental mammals that also includes sloths and anteaters. Xenarthrans (Greek for "strange joints") exhibit a strange property called, you guessed it, xenarthry, which refers to the extra articulations in these animals' backbones. They are also characterized by the unique shape of their hips, their low body temperatures, and the internal testicles of males. In the face of accumulated genetic evidence, the superorder Xenarthra was split into two orders: Cingulata, which includes armadillos, and Pilosa, which comprises sloths and anteaters. Pangolins and aardvarks, which superficially resemble armadillos and anteaters, respectively, are unrelated mammals, the features of which can be chalked up to convergent evolution.

06
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Armadillos Hunt With Their Sense of Smell

An armadillo digging

Andrea Izzotti / Getty Images

Like most small, skittering mammals that live in burrows, armadillos rely on their acute sense of smell to locate prey and avoid predators (a nine-banded armadillo can sniff out grubs buried six inches beneath the soil), and they have relatively weak eyes. Once an armadillo homes in on an insect nest, it quickly digs through the dirt or soil with its large front claws. The holes can be a huge nuisance to homeowners, who may have no choice but to call a professional exterminator. Some armadillos are also good at holding their breath for extended periods of time; for example, the nine-banded armadillo can stay underwater for as long as six minutes.

07
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Nine-Banded Armadillos Give Birth to Identical Quadruplets

Mother armadillo and her baby rooting for bugs in a log

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Among humans, giving birth to identical quadruplets is literally a one-in-a-million event, much rarer than identical twins or triplets. However, nine-banded armadillos accomplish this feat all the time: After fertilization, the egg of the female splits into four genetically identical cells, which go on to produce four genetically identical offspring. Why this happens is a bit of a mystery. It's possible that having four identical offspring of the same sex reduces the risk of inbreeding when the juveniles mature, or it may just be an evolutionary quirk from millions of years ago that somehow got "locked into" the armadillo genome because it didn't have any long-term disastrous consequences.

08
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Armadillos Are Often Used to Study Leprosy

A microscopic image of the bacteria causing leprosy
A microscopic image of the bacteria causing leprosy.

Marwani22 / Getty Images

One odd fact about armadillos is that, along with their xenarthran cousins sloths and anteaters, they have relatively sluggish metabolisms and low body temperatures. This makes armadillos especially susceptible to the bacterium that causes leprosy (which needs a cool skin surface on which to propagate), and thus makes these mammals ideal test subjects for leprosy research. Animals typically transmit diseases to humans, but in the case of armadillos, the process seems to have worked in reverse. Until the arrival of European settlers in South America 500 years ago, leprosy was unknown in the New World, so a series of unfortunate armadillos must have been picked up (or even adopted as pets) by Spanish conquistadors.

09
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Armadillos Used to Be Much Bigger

A fossil of a Glyptodon
Wikimedia Commons

During the Pleistocene epoch 1 million years ago, mammals came in much bigger packages than they do today. Along with the three-ton prehistoric sloth Megatherium and the bizarre-looking hoofed mammal Macrauchenia, South America was populated by the likes of Glyptodon, a 10-foot-long, one-ton armadillo that feasted on plants rather than insects. Glyptodon lumbered across the Argentinean pampas right up to the cusp of the last Ice Age. The earliest human settlers of South America occasionally slaughtered these giant armadillos for their meat and used their capacious shells to shelter themselves from the elements.

10
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Charangos Were Once Made From Armadillos

Charangos for sale at Saturday crafts market, South America

Danita Delimont / Getty Images

A variant of the guitar, charangos became popular among the indigenous peoples of northwestern South America after the arrival of European settlers. For hundreds of years, the soundbox (resonating chamber) of the typical charango was made from the shell of an armadillo, perhaps because Spanish and Portuguese colonialists prohibited the natives from using wood, or perhaps because the smallish shell of an armadillo could more easily be tucked into native garments. Some classic charangos are still made out of armadillos, but wooden instruments are much more common (and presumably less distinctive sounding).