Armadillo Temporal range: Paleocene – Recent Late | |
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From top to bottom † Glyptodon , nine-banded armadillo (Dasypus novemcinctus), pink fairy armadillo (Chlamyphorus truncatus) | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Superorder: | Xenarthra |
Order: | Cingulata |
Families | |
Armadillos (Spanish for 'little armored ones') are New World placental mammals in the order Cingulata. They form part of the superorder Xenarthra, along with the anteaters and sloths. 21 extant species of armadillo have been described, some of which are distinguished by the number of bands on their armor. All species are native to the Americas, where they inhabit a variety of different environments.
Living armadillos are characterized by a leathery armor shell and long, sharp claws for digging. They have short legs, but can move quite quickly. The average length of an armadillo is about 75 cm (30 in), including its tail. The giant armadillo grows up to 150 cm (59 in) and weighs up to 54 kg (119 lb), while the pink fairy armadillo has a length of only 13–15 cm (5–6 in). When threatened by a predator, Tolypeutes species frequently roll up into a ball; they are the only species of armadillo capable of this.
Recent genetic research has shown that the megafaunal glyptodonts (up to 1.5 metres (4.9 ft) tall with maximum body masses of around 2 tonnes), which became extinct around 12,000 years ago are true armadillos more closely related to all other living armadillos than to Dasypus (the long-nosed or naked-tailed armadillos). Armadillos are currently classified into two families, Dasypodidae, with Dasypus as the only living genus, and Chlamyphoridae, which contains all other living armadillos as well as the glyptodonts. [1]
The word armadillo means "little armored one" in Spanish; [2] [3] it is derived from "armadura" (armor), with the diminutive suffix "-illo" attached. While the phrase "little armored one" would translate to "armadito" normally, the suffix "-illo" can be used in place of "-ito" when the diminutive is used in an approximative tense. [4] The Aztecs called them āyōtōchtli [aːjoːˈtoːt͡ʃt͡ɬi] , Nahuatl for "turtle-rabbit": āyōtl [ˈaːjoːt͡ɬ] (turtle) and tōchtli [ˈtoːt͡ʃt͡ɬi] (rabbit). [5] The Portuguese word for "armadillo" is tatu which is derived from the Tupi language [6] ta' "bark, armor" and tu "dense"; [7] and used in Argentina, Bolivia, Brasil, Paraguay and Uruguay; similar names are also found in other, especially European, languages.
Other various vernacular names given are:
Family Dasypodidae
Family Chlamyphoridae
† indicates extinct taxon
Below is a recent simplified phylogeny of the xenarthran families, which includes armadillos. [10] [11] The dagger symbol, "†", denotes extinct groups.
Xenarthra |
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Recent genetic research suggests that an extinct group of giant armored mammals, the glyptodonts, should be included within the lineage of armadillos, having diverged some 35 million years ago, more recently than previously assumed. [12]
Like all of the Xenarthra lineages, armadillos originated in South America. Due to the continent's former isolation, they were confined there for most of the Cenozoic. The recent formation of the Isthmus of Panama allowed a few members of the family to migrate northward into southern North America by the early Pleistocene, as part of the Great American Interchange. [13] (Some of their much larger cingulate relatives, the pampatheres and chlamyphorid glyptodonts, made the same journey.) [13]
Today, all extant armadillo species are still present in South America. They are particularly diverse in Paraguay (where 11 species exist) and surrounding areas. Many species are endangered. Some, including four species of Dasypus , are widely distributed over the Americas, whereas others, such as Yepes's mulita, are restricted to small ranges. Two species, the northern naked-tailed armadillo and nine-banded armadillo, are found in Central America; the latter has also reached the United States, primarily in the south-central states (notably Texas), but with a range that extends as far east as North Carolina and Florida, and as far north as southern Nebraska and southern Indiana. [14] Their range has consistently expanded in North America over the last century due to a lack of natural predators. Armadillos are increasingly documented in southern Illinois and are tracking northwards due to climate change. [15]
The smallest species of armadillo, the pink fairy armadillo, weighs around 85 g (3.0 oz) and is 13–15 cm (5.1–5.9 in) in total length. The largest species, the giant armadillo, can weigh up to 54 kg (119 lb), and can be 150 cm (59 in) long. [16]
The diets of different armadillo species vary, but consist mainly of insects, grubs, and other invertebrates. Some species, however, feed almost entirely on ants and termites.
They are prolific diggers. 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 around which it lives and feeds.
Armadillos have very poor eyesight, and use their keen sense of smell to hunt for food. [16] They use their claws not only for digging and finding food but also for digging burrows for their dwellings, each of which is a single corridor the width of the animal's body. They have five clawed toes on their hind feet, and three to five toes with heavy digging claws on their fore feet. Armadillos have numerous cheek teeth which are not divided into premolars and molars, but usually have no incisors or canines. The dentition of the nine-banded armadillo is P 7/7, M 1/1 = 32. [17]
In common with other xenarthrans, armadillos, in general, have low body temperatures of 33–36 °C (91–97 °F) and low basal metabolic rates (40–60% of that expected in placental mammals of their mass). This is particularly true of types that specialize in using termites as their primary food source (for example, Priodontes and Tolypeutes ). [18]
The armor is formed by plates of dermal bone covered in relatively small overlapping epidermal scales called "scutes" which are composed of keratin. [19] The skin of an armadillo can glow under ultraviolet light. [20] Most species have rigid shields over the shoulders and hips, with a number of bands separated by flexible skin covering the back and flanks. Additional armor covers the top of the head, the upper parts of the limbs, and the tail. The underside of the animal is never armored and is simply covered with soft skin and fur. [21] This armor-like skin appears to be an important defense for 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. When surprised, the North American nine-banded armadillo tends to jump straight in the air, which can lead to a fatal collision with the undercarriage or fenders of passing vehicles. [22]
Armadillos have short legs, but can move quite quickly. The nine-banded armadillo is noted for its movement through water, [23] which is accomplished via two different methods: it can walk underwater for short distances, holding its breath for as long as six minutes; or, to cross larger bodies of water, it can increase its buoyancy by swallowing air to inflate its stomach and intestines. [24]
Gestation lasts from 60 to 120 days, depending on species, although the nine-banded armadillo also exhibits delayed implantation, so the young are not typically born for eight months after mating. Most members of the genus Dasypus give birth to four monozygotic young (that is, identical quadruplets), [25] but other species may have typical litter sizes that range from one to eight. The young are born with soft, leathery skin which hardens within a few weeks. They reach sexual maturity in three to twelve months, depending on the species. Armadillos are solitary animals that do not share their burrows with other adults. [21]
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 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, Mycobacterium leprae . (The leprosy bacterium is difficult to culture and armadillos have a body temperature of 34 °C (93 °F), similar to human skin.) [26] Humans can acquire a leprosy infection from armadillos by handling them or consuming armadillo meat. [27] [28] Armadillos are a presumed vector and natural reservoir for the disease in Texas, Louisiana and Florida. [29] [30] Prior to the arrival of Europeans in the late 15th century, leprosy was unknown in the New World. Given that armadillos are native to the New World, at some point they must have acquired the disease from old-world humans. [27] [30]
The armadillo is also a natural reservoir for Chagas disease. [31]
The nine-banded armadillo also serves science through its unusual reproductive system, in which four genetically identical offspring are born, the result of one original egg. [32] [33] [34] Because they are always genetically 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 is the only reliable manifestation of polyembryony in the class Mammalia, and exists only within the genus Dasypus and not in all armadillos, as is commonly believed. Other species that display this trait include parasitoid wasps, certain flatworms, and various aquatic invertebrates. [33]
Even though they have a leathery, tough shell, Armadillos, (mainly Dasypus) are common roadkill due to their habit of jumping 3–4 ft vertically when startled, which puts them into collision with the underside of vehicles. [35] Wildlife enthusiasts are using the northward march of the armadillo as an opportunity to educate others about the animals, which can be a burrowing nuisance to property owners and managers. [32]
Armadillo shells have traditionally been used to make the back of the charango , an Andean lute instrument.
In certain parts of Central and South America, armadillo meat is eaten; it is a popular ingredient in Oaxaca, Mexico. During the Great Depression, Americans were known to eat armadillo, known begrudgingly as "Hoover hogs", a nod to the belief that President Herbert Hoover was responsible for the economic despair facing the nation at that time. [36] [37]
A whimsical account of The Beginning of the Armadillos is one of the chapters of Rudyard Kipling's Just So Stories 1902 children's book. [38] The vocal and piano duo Flanders and Swann recorded a humorous song called "The Armadillo". [39]
Shel Silverstein wrote a two-line poem called "Instructions" on how to bathe an armadillo in his collection A Light in the Attic. The reference was "use one bar of soap, a whole lot of hope, and 27 pads of Brillo."
Xenarthra is a major clade of placental mammals native to the Americas. There are 31 living species: the anteaters, tree sloths, and armadillos. Extinct xenarthrans include the glyptodonts, pampatheres and ground sloths. Xenarthrans originated in South America during the late Paleocene about 60 million years ago. They evolved and diversified extensively in South America during the continent's long period of isolation in the early to mid Cenozoic Era. They spread to the Antilles by the early Miocene and, starting about 3 million years ago, spread to Central and North America as part of the Great American Interchange. Nearly all of the formerly abundant megafaunal xenarthrans became extinct at the end of the Pleistocene.
Glyptodonts are an extinct clade of large, heavily armoured armadillos, reaching up to 1.5 metres (4.9 ft) in height, and maximum body masses of around 2 tonnes. They had short, deep skulls, a fused vertebral column, and a large bony carapace made up of hundreds of individual scutes. Some glyptodonts had clubbed tails, similar to ankylosaurid dinosaurs.
Cingulata, part of the superorder Xenarthra, is an order of armored New World placental mammals. Dasypodids and chlamyphorids, the armadillos, are the only surviving families in the order. Two groups of cingulates much larger than extant armadillos existed until recently: pampatheriids, which reached weights of up to 200 kg (440 lb) and chlamyphorid glyptodonts, which attained masses of 2,000 kg (4,400 lb) or more.
The six-banded armadillo, also known as the yellow armadillo, is an armadillo found in South America. The sole extant member of its genus, it was first described by Swedish zoologist Carl Linnaeus in 1758. The six-banded armadillo is typically between 40 and 50 centimeters in head-and-body length, and weighs 3.2 to 6.5 kilograms. The carapace is pale yellow to reddish brown, marked by scales of equal length, and scantily covered by buff to white bristle-like hairs. The forefeet have five distinct toes, each with moderately developed claws.
The nine-banded armadillo, also known as the nine-banded long-nosed armadillo or common long-nosed armadillo, is a mammal found in North, Central, and South America, making it the most widespread of the armadillos. Its ancestors originated in South America, and remained there until the formation of the Isthmus of Panama allowed them to enter North America as part of the Great American Interchange. The nine-banded armadillo is a solitary, mainly nocturnal animal, found in many kinds of habitats, from mature and secondary rainforests to grassland and dry scrub. It is an insectivore, feeding chiefly on ants, termites, and other small invertebrates. The armadillo can jump 91–120 cm (3–4 ft) straight in the air if sufficiently frightened, making it a particular danger on roads. It is the state small mammal of Texas.
The southern three-banded armadillo, also known as La Plata three-banded armadillo or Azara's domed armadillo, is an armadillo species from South America. It is found in parts of northern Argentina, southwestern Brazil, Paraguay and Bolivia, at elevations from sea level to 770 m (2,530 ft).
The Brazilian three-banded armadillo is an armadillo species endemic to eastern Brazil, where it is known as tatu-bola. It is one of only two species of armadillo that can roll into a ball. It has suffered a 30% decline in population in the last 10 years.
The Andean hairy armadillo is an armadillo found mainly in Bolivia, in the region of the Puna; the departments of Oruro, La Paz, and Cochabamba. Nowark (1991) describes it as distributed in Bolivia and northern Chile. A recent publication of Pacheco (1995) also locates the species in the Puno Region of Peru. This species is also thought to be present in northern Argentina. However, this location may actually only contain a population of C. vellerosus.
The northern naked-tailed armadillo is a species of armadillo. It is one of only two species of armadillo found outside of South America, the other being the more widely distributed nine-banded armadillo.
Dasypus bellus, the beautiful armadillo, is an extinct armadillo species endemic to North America and South America from the Pleistocene, living from 1.8 mya—11,000 years ago, existing for approximately 1.789 million years.
Dasypus is the only extant genus in the family Dasypodidae. Its species are known as long-nosed or naked-tailed armadillos. They are found in South, Central, and North America, as well as on the Caribbean islands of Grenada, Trinidad and Tobago. Members of Dasypus are solitary and primarily nocturnal to avoid temperature extremes and predation. They exist in numerous habitats ranging from brush to grassland areas and are mainly insectivorous.
Tolypeutinae is a subfamily of armadillos in the family Chlamyphoridae, consisting of the giant, three-banded and naked-tailed armadillos.
The genus Tolypeutes contains the two species of three-banded armadillos. They are restricted to open and semi-open habitats in South America.
The Llanos long-nosed armadillo or northern long-nosed armadillo is a species of armadillo in the family Dasypodidae. It is endemic to Colombia and Venezuela, where its habitat is the intermittently flooded grassland of the Llanos. The species is closely related to the nine-banded armadillo and the great long-nosed armadillo. It has very little hair and can weigh up to 22 pounds (9.5 kg), and can grow to about 2.1 feet (60 cm) long. It lives in dense cover near limestone formations. Like most other armadillos, it eats ants.
Euphractinae is an armadillo subfamily in the family Chlamyphoridae.
Chlamyphoridae is a family of cingulate mammals. While glyptodonts have traditionally been considered stem-group cingulates outside the group that contains modern armadillos, there had been speculation that the extant family Dasypodidae could be paraphyletic based on morphological evidence. In 2016, an analysis of Doedicurus mtDNA found it was, in fact, nested within the modern armadillos as the sister group of a clade consisting of Chlamyphorinae and Tolypeutinae. For this reason, all extant armadillos but Dasypus were relocated to a new family.
The plates of bone are covered in small overlapping epidermal scales called scutes, which are composed of keratin.