Armadillo is the common name for any of the small, placental, Old World mammals comprising the family Dasypodidae and characterized by a bony armor shell. There are approximately ten extant (living) genera of armadillo and around 20 extant species, some of which are distinguished by the number of bands on their armor. Armadillo also is used for members of the order Cingulata (previously Edentata) within which Dasypodidae is placed.
Armadillos provide some unique values for humans. For one, armadillos are often used in the study of leprosy, since they are among the few known non-human animal species that can contract the disease systemically. The nine-banded armadillo, Dasypus novemcinctus, also serves science through the fact that four identical quadruplets are born in each litter, providing a good subject for scientific, behavioral, or medical tests that need consistent biological and genetic makeup in the test subjects. Armadillos also add to the wonder of nature for humans, including the propensity of some to roll themselves into a tight ball when threatened.
Dasypodidae is the only surviving family in the order Cingulata, which also includes extinct families. Cingulata is part of the superorder Xenarthra, which also includes the anteaters and sloths. In the past, these families were classified together with the pangolins and aardvark as the order Edentata, meaning toothless, because the members do not have front incisor teeth or molars, or have poorly-developed molars. It was subsequently realized that Edentata was polyphyletic—that it contained unrelated families and was thus invalid by cladistic standards. Aardvarks and pangolins are now placed in individual orders. The name Xenarthra means "strange joints," and was chosen because their vertebral joints are unlike those of any other mammals.
All species of armadillo are native to the Americas, where they inhabit a variety of environments. In the United States, the sole resident armadillo is the nine-banded armadillo (Dasypus novemcinctus), which is most common in the central southernmost states, particularly Texas.
Armadillo is Spanish for "little armored one," referring to their outer skin that looks like armor.
Armadillos are short-legged mammals, covered by armor-like jointed plates made up of bone or horny material, separated by flexible tissue. The smallest armadillo, the pink fairy armadillo or pichiciego (Chlamyphorus truncatus), found in Argentina, is approximately 90-115 millimeters (3.5-4.5 inches) long excluding the tail. The giant armadillo or tatou (Priodontes maximus) is the largest species of armadillo, with adults typically weighing around 27 kg (59 lbs) when full grown and a typical length of 895 millimeters (35 inches), of which a third to two-fifths is likely to be accounted for by the tail.
Armadillos are prolific diggers, and many species use their sharp claws to dig for food such as grubs, and to dig dens. The nine-banded armadillo prefers to build burrows in moist soil near the creeks, streams, and arroyos near which it lives and feeds. The diet of different armadillo species varies, but consists mainly of insects, grubs, and other invertebrates. Some species, however, are almost entirely formicivorous (feeding mainly on ants).
Armadillos have poor vision, but are not blind.
The armor is formed by plates of dermal bone covered in small, overlapping epidermal scales called "scutes." This armor-like skin appears to be the main defense of many armadillos, although most escape predators by fleeing (often into thorny patches, from which their armor protects them) or digging to safety. Only the South American three-banded armadillos (Tolypeutes) rely heavily on their armor for protection. When threatened by a predator, Tolypeutes species frequently roll up into a ball. (Other armadillo species cannot roll up because they have too many plates.) The North American nine-banded armadillo tends to jump straight in the air when surprised, and consequently often collides with the undercarriage or fenders of passing vehicles (LOC 2007).
Armadillos have short legs but can move quickly, and have the ability to remain underwater for as long as six minutes. Because of the weight of its armor, an armadillo will sink in water unless it inflates its stomach with air, which often doubles its size (Portillo 1999).
Armadillos use their claws for digging and finding food, as well as for making their homes in burrows. They dig their burrows with their claws, only making a single corridor where they themselves fit.
† indicates extinct taxon
Armadillos are often used in the study of leprosy, since they, along with mangabey monkeys, rabbits and mice (on their footpads), are among the few known non-human animal species that can contract the disease systemically. They are particularly susceptible due to their unusually low body temperature, which is hospitable to the leprosy bacterium.
The nine-banded armadillo, Dasypus novemcinctus, also serves science through its unusual reproductive system, in which four identical quadruplets are born in each litter (Schaefer and Hostetler). Because they are always identical, the group of four young provides a good subject for scientific, behavioral, or medical tests that need consistent biological and genetic makeup in the test subjects. This phenomenon of multiple identical birth, called polyembryony, only manifests in the genus Dasypus and not in all armadillos, as is commonly believed.
Armadillos (mainly Dasypus) make common roadkill due to their habit of jumping to about fender height when startled (such as by an oncoming car).
Wildlife enthusiasts are using the northward march of the nine-banded armadillo as an opportunity to educate others about the animals, which can be a burrowing nuisance to homeowners, cemetery caretakers, and golf course superintendents (Schaefer and Hostetler).
During the Great Depression in the United States, the nine-banded armadillo was known as "Hoover Hog" by down-on-their luck Americans who had to eat them instead of the "chicken in every pot" Herbert Hoover had promised as President (Smith 2001). Earlier, German settlers in Texas would often refer to the armadillo as Panzerschwein ("armored pig").
The nine-banded armadillo was, with some resistance, made the state small mammal of Texas, where it is considered a pest and is often seen dead on the roadside. They first forayed into Texas across the Rio Grande from Mexico in the 1800s, eventually spreading across the southeast United States (Smith 2001).
All links retrieved November 5, 2012.
|Monotremata (platypus, echidnas)|
Marsupialia: | Paucituberculata (shrew opossums) | Didelphimorphia (opossums) | Microbiotheria | Notoryctemorphia (marsupial moles) | Dasyuromorphia (quolls and dunnarts) | Peramelemorphia (bilbies, bandicoots) | Diprotodontia (kangaroos and relatives)
Placentalia: Cingulata (armadillos) | Pilosa (anteaters, sloths) | Afrosoricida (tenrecs, golden moles) | Macroscelidea (elephant shrews) | Tubulidentata (aardvark) | Hyracoidea (hyraxes) | Proboscidea (elephants) | Sirenia (dugongs, manatees) | Soricomorpha (shrews, moles) | Erinaceomorpha (hedgehogs and relatives) Chiroptera (bats) | Pholidota (pangolins)| Carnivora | Perissodactyla (odd-toed ungulates) | Artiodactyla (even-toed ungulates) | Cetacea (whales, dolphins) | Rodentia (rodents) | Lagomorpha (rabbits and relatives) | Scandentia (treeshrews) | Dermoptera (colugos) | Primates |
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