The Nine-banded Armadillo is an odd creature. It seems half reptile, half mammal. Its bony shell protects it from most predators, but not from a certain human disease. Wikimedia Commons Photo.
03/07/2015 – A Mammal That Resembles a Reptile
Armadillos are such odd creatures. Although they are warm-blooded and have hair (on their undersides), they have a bony, protective shell on their backs and heads. They are the size of a terrier but are armed like a tank. No wonder the Aztecs called them “ayotochitl” which means “turtle-rabbit.” What a descriptive name!
You probably know that armadillos are fairly common mammals in Texas and the south-eastern United States. But they haven’t always been here. The family Dasypodidae includes about twenty species of armadillo in existence today, most of which live in South and Central America. The Nine-banded Armadillo, our local species, is the only one found in the United States.
The family originated in South America when it was a separate continent. During the last Ice Age, the Isthmus of Panama formed. A couple of million years ago, the isthmus provided a land-bridge for the Nine-banded Armadillo to move north.
A few Dasypodidae relatives also came north. Have you ever seen the fossil known as a glyptodont? It was a sort of giant armadillo…about the size and shape of a Volkswagen “beetle.” The Nine-banded Armadillo is its puny, surviving relative.
In fact, it seems our Nine-banded Armadillo didn’t even arrive in south Texas until the 1800s. It was well known in Mexico, but its range did not include any of the United States. Somewhere in the mid-19th century, this curious mammal began expanding its range. First it was found in south Texas, then east Texas, then Louisiana and on into the soft, sandy soils of the Gulf Coast. It is now a resident of Florida and Georgia. Armadillos are also found as far north as Nebraska and Missouri.
But the armadillo is basically a tropical animal. It cannot stand prolonged cold and it is unable to hibernate. Therefore, it is unlikely to extend its range much farther north.
In addition to climate restrictions, the armadillo is limited to areas of relatively soft soil. It feeds chiefly on insects which it grubs out of the soil. You have probably seen the triangular excavations, an inch or so deep, that an armadillo leaves after it has worked over an area.
In places with hard or rocky ground, armadillos generally confine their activities to the edges of streams. They frequently dig out burrows in the moister soil of riverbanks. But the poor armadillo is not really equipped for an aquatic life. Its body is so dense that it sinks in water. To cross a small stream, an armadillo just walks across on the bottom while holding its breath. Now that would be a sight to see!
For larger bodies of water, an armadillo swallows air until it is buoyant enough to float, then paddles its ungainly body across. I am somewhat incredulous about this. How would you know the animal was swallowing air? How does it know to do this? I would really like to see such behavior for myself.
One fact about the armadillo is well-documented. The female almost always gives birth to four babies, all of the same sex. Biologists have discovered that the Nine-banded Armadillo is the only species that produces identical quadruplets. This means that the babies are genetically exactly alike. These individuals are useful in medical research, particularly on treatments for leprosy.
Yes, leprosy is still with us. Once a Biblical scourge, leprosy is now known to be much less contagious than it was believed to be. It is classified as a very rare disease, and fewer than 250 cases a year are diagnosed in the US. Most of these cases are contracted abroad. Last October, however, three cases were confirmed in Florida, and these seem to have been contracted from armadillos.
It is an odd twist of fate that only humans and armadillos are susceptible to leprosy. It is even odder that armadillos are actually the victims in this scenario. Most researchers believe that armadillos first contracted the disease from human explorers to the New World. It is now suspected that 20% of armadillos are infected.
What makes armadillos susceptible to what is essentially a human disease? It seems it is their body temperature is low for a mammal, only about 93 degrees. Human skin temperature is generally in this range, too. The bacterium that causes leprosy, more appropriately called Hansen’s Disease, attacks the skin first and later moves on to damage nerve endings. If caught early, Hansen’s Disease is easily cured with antibiotics. The problem lies with getting an early diagnosis of a very rare disease, and one that may have an incubation period of twenty years!
It is simple to avoid getting leprosy from infected armadillos. Just don’t touch an armadillo. Don’t hunt, skin, or eat armadillos. You cannot get leprosy without direct contact with an infected individual. Even then it is unlikely, as 95% of us humans are naturally immune. And only a small percentage of armadillos have the disease. But why take a chance?
Still, as a young teen, I touched an armadillo. I lived in Lake Jackson, Texas, a newly settled suburb and a few armadillos roamed around our backyard. One afternoon I sat quietly on the back steps watching the sunset when an armadillo muddled out near me. As he searched for insects in the lawn, he was oblivious to my presence. Their eyesight is poor and he didn’t seem to detect me by smell. So I reached out and touched him on his shell: Just a gentle “knock, knock.” He jumped three feet straight up in the air! I am pretty sure I did too.
This startle reaction is often observed in armadillos. It has earned them the nickname: the Hillbilly Speed Bump. When a foraging armadillo wanders on to a road and is startled by a vehicle, the animal’s response is to jump up. Unfortunately that means it hits the fender or the undercarriage of the car.
These poor animals! They are nearly blind, can’t take the cold, sink in water, jump up into the path of moving vehicles, and now, because of a human disease, are “untouchables.” I guess it is a good thing they have that armor or they would be extinct by now.
If you would like to offer comments, please click through to the discussion page