Armadillos are the only mammals other than humans that can contract and carry leprosy. It is unclear why armadillos, which are so distantly related to humans, are the only other mammals to carry the disease. Because of this unique feature, dasypodids have been used as models for biomedical research with leprosy. Despite relatively high rates of carrying the disease in certain areas (especially the southern United States), health risk to humans has been deemed low by many studies, as transmission between armadillos and humans is difficult.
Teeth are of little use to most members of Dasypodidae. They mostly eat insects, which require minimal chewing. Giant armadillos (Priodontes maximus), whose scientific name ironically means "biggest saw-teeth" in Greek, primarily eat ants and termites and cannot use their teeth for mastication because they are too weak.
Two of the major threats currently facing wild armadillos are domestic dogs and humans (many armadillo species are hunted for their meat). Wild cats (pumas and jaguars), wild dogs (coyotes and bush dogs), and bears may also prey on dasypodids, although predation does not seem to have a large effect on armadillo populations.
When threatened, armadillos often retreat to the safety of a burrow. Their armor also acts as a deterrent to predators. However, there is considerable variation in response to predators among dasypodids. For example, armadillos of the genus Tolypeutes can roll completely into a ball, while nine-banded armadillos (Dasypus novemcinctus) have the ability to leap vertically into the air. If a nine-banded armadillo (D. novemcinctus) is captured by a predator, its most common response is to play dead. Some speices, such as hairy armadillos (Chaetophractus nationican), snarl to frighten predators. As a last resort, armadillos may use their powerful digging legs to claw at attackers.
Known Predators:
All members of Dasypodidae have armor on their sides, back and tail, as well as the top of their head, which makes up their characteristic “shell.” This armor is composed of a series of plates of ossified scutes covered with a leathery keratinous skin. The scutes are arranged into movable bands, which usually overlap to effectively seal gaps in the armor. Areas of soft skin and sometimes hair are located between the bands. In some species, the ventral surface is covered in dense hairs. The belly is soft and unprotected by bone, although some species are able to curl into a ball. The limbs have irregular plates covering at least parts of their surfaces, and they also may be hairy. The top of the head is always covered by a shield of keratin-covered scutes, and the long rat-like tail is covered by bony rings.
The armor may be an adaptation for protection and defense against predation, but also could serve as protection against abrasive soil and biting insects (beneficial to the fossorial lifestyle). The arrangement of armor plates and bands varies widely and is used to differentiate species and families. The armor may constitute fifteen percent of the animal's entire body weight.
Dasypodids range in size from pink fairy armadillos (Chlamyphorus truncatus: 90 g, 11.4 to 15 cm) to giant armadillos (Priodontes maximus: 50 kg, 80 to 100 cm). Armadillos have a long snout, and their ears range in size from small to very large and protuberant. Sexual dimorphism is limited, but sometimes males are slightly larger. Males have no scrotum, and their testes do not descend past the pelvic girdle. Females lack a true vagina, but instead have a singular urogenital exit. Body colors are mostly gray or brown, though pink fairy armadillos have a pinkish shell and pure white, dense fur on their sides and venters.
Dasypodids can be considered slightly heterothermic, because their regulatory systems are not advanced enough to completely prevent fluctuations in body temperature due to changes in ambient temperature. However, they do maintain a relatively constant body temperature under non-stressful conditions and thus are typically described as homoiothermic.
Most armadillos have short, thick limb bones that include expanded crests and processes for the attachment of muscles. The tibia and fibula are fused both proximally and distally. Digging habits and abilities are correlated with forelimb, but not hindlimb, morphology. Armadillo forelimbs have 3 to 5 toes, depending on the species, but their hindlimbs always have 5. The toes are armed with heavy, curved claws, which aid in digging and defense.
The postcranial skeleton of armadillos is modified for digging and to accommodate the armor. The axial skeleton is rigid and may or may not contact the carapace. The pelvis of some species is especially strongly built and enlarged. The ribs may be broadened, and parts of ribs that in most mammals are cartilage are ossified in some species of armadillos.
Armadillos have a flattened skull and a flattened, long lower jaw. The zygomatic arch is complete and a jugal is present. Armadillo dentition is simple and homodont, as the teeth similar, reduced, and peg-like in adults. Adults lack canines, and most have no incisors. Dasypodids actually have 4 to 6 primordial incisors at birth, but these teeth are absorbed early in life. The premaxillae and lacrimals are small. Their dental formulae simply provide upper / lower (number of upper over number of lower teeth) due to the lack of incisors and canines and similarity between the peg-like teeth that do exist. After development is complete, cheek teeth (molars and premolars) vary from 7-8/7-8 to 18/19. Adult teeth completely lack enamel and are made up of a dentine core surrounded by cementum, which wears down very easily. Dental formula and tooth shape vary among species, and even among members of the same species, due to different wear patterns and differences in developmental patterns among individuals.
Other Physical Features: endothermic ; heterothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike; male larger
The lifespan of armadillos varies with species. Some species live only 9 years (Zaedyus pichiy), while others can live as long as 23 years (Chaetophractus villosus). In captivity, Euphractus sextinctus has been documented to live up to 18 years, and Tolypeutes matacus up to 17.
Among nine-banded armadillos (Dasypus novemcinctus), prenatal mortality is common, and juveniles tend to have a higher mortality rate than adults. Pre- and postnatal mortality information for this and other species, however, is not well known.
Armadillos are found in a wide array of habitats, from deserts and mountains to wetlands and sandy coastal regions. All members of Dasypodidae are terrestrial, and most are fossorial, living in burrows. They typically remain on the ground, because their plated armor and heavy bones prevent them from climbing trees (as with most members of the closely related family Pilosa) or swimming. Dasypus novemcinctus is an exception, as it is known to swim awkwardly. Some dasypodids, such as members of Tolypeutinae, are strictly terrestrial and not fossorial.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral ; forest ; rainforest ; scrub forest ; mountains
Aquatic Biomes: coastal
Wetlands: swamp
Other Habitat Features: suburban ; agricultural ; riparian
Armadillos have a strictly New World distribution, ranging from the central United States (Missouri) through Central and South America, as far south as Cape Horn (at the southern tip of South America).
Nine-banded armadillos (Dasypus novemcinctus) have the most northern distribution. Their range originally spanned from South America into Mexico but has expanded steadily northward into the Southern United States Their range currently extends throughout the Midwest, and nine-banded armadillos have recently been found as far north as Nebraska. Scientists speculate that global climate change and loss of natural predators could contribute to the northward expansion of this typically more neotropical species.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Armadillos are primarily insectivorous, although diet varies greatly among species. Some species are omnivorous foragers, feeding on a variety of sources such as small animals, plant matter, insects, and arachnids. Others are strictly myrmecophagic (ant-eating), using the sticky substance on their tongues to capture large numbers of insects. Some members of Dasypodidae eat carrion, and there have been documented cases of armadillos raiding human graveyards in South America.
Armadillos have very poor eyesight and thus hunt and find food primarily with their sense of smell. Armadillos are strong diggers and use their claws to dig up a variety of otherwise unavailable food sources. Another indication of their generalist life-style is their lack of specialized teeth.
Primary Diet: carnivore (Eats terrestrial vertebrates, Eats eggs, Insectivore , Eats non-insect arthropods, Scavenger ); herbivore (Folivore , Frugivore ); omnivore
Although armadillos can exist in relatively high densities (dasypodids account for the highest mammalian biomass after sloths in tropical rainforests), they have relatively little impact on their respective environments. This is due in part to their low metabolism. Additionally, armadillos primarily prey upon invertebrates, which have extremely short life cycles so populations are able to recover from predation quickly. As omnivores, most species of armadillos do not heavily rely on any single prey source. As a result, dasypodids do not seem to exhibit much of an impact on prey populations.
Armadillos are generally terrestrial to fossorial and can thrive in a variety of habitats. They are known for their tendency to construct elaborate burrows on agricultural land. While a nuisance to farmers, these burrows provide homes for a variety of other species, including rabbits, skunks, and possums.
Armadillos are relatively resistant to parasites, as their shells and sparsely-haired venters limit their vulnerability to ectoparasites. Among those that do affect members of Dasypodidae are fungi, viruses, protozoans, helminths, and various arthropods. Armadillo species in South America have a noticeably wider array of arthropod parasites than their North American counterparts, although throughout the range of Dasypodidae there are only around fifty known parasites. Armadillos are known to host the bacterium Mycobacterium leprae, which causes leprosy. Transmission to humans is rare, but possible.
Ecosystem Impact: creates habitat
Commensal/Parasitic Species:
Armadillos have long been used as a food source in a variety of cultures, and although certain species such as giant armadillos (Priodontes maximus) are being over-harvested, most populations remain stable. Armadillos help control the populations of a variety of harmful insect species, including fire ants (Solenopsis). The negative view of armadillos by the agriculture industry is slowly changing, in part due to the fact that armadillos are the only predator of fire ants in North America. Dasypodids are also used in research on reproduction, as some species are able to produce identical, same-sex offspring. In addition, armadillos are used to study organ transplants, birth defects, and diseases including leprosy, typhus, and trichinosis.
Positive Impacts: food ; research and education; controls pest population
Armadillos are generally viewed as pests, as they can cause destruction of suburban and agricultural areas through excessive digging. This view is especially prominent within the agricultural community, as holes created by burrowing species of Dasypodidae can harm both crops and livestock. Additionally, armadillos host the bacterium Mycobacterium leprae, which causes leprosy. Transmission to humans, while rare, is possible. The public view of dasypodids, is slowly becoming more positive as awareness of their economic benefits increases.
Negative Impacts: injures humans (carries human disease)
Dasypodidae is the only extant family in the order Cingulata, which also contains extinct families Glyptodontidae and Pampatheriidae. Dasypodidae contains three subfamilies: Tolypeutinae, Euphractinae, and Dasypodinae. These are further divided into one, six and three genera, respectively. Armadillos are by far the most diverse group of xenarthrans, with a total of twenty-one extant species and two extinct species identified in the family Dasypodidae. These species vary in size, form, and behavior, but all possess characteristic bony armor.
While only two members of Dasypodidae, giant armadillos (Priodontes maximus) and pink fairy armadillos (Chlamyphorus truncatus), are listed as endangered, 12 of 20 members are currently listed as vulnerable, endangered, near threatened, or data deficient. Because many species of Dasypodidae are fossorial, they have not been thoroughly studied, so the status of many groups is not well defined. For example, hairy long-nosed armadillos (Dasypus pilosus) are recognized as a species based only on a few skins from Peru. Due to a lack of information, it is very difficult to ascertain the exact conservation status of many dasypodids.
The main threats facing Dasypodidae are exploitation for food and habitat loss. As land is converted for agriculture, potential habitat for both giant armadillos (Priodontes maximus) and pink fairy armadillos (Chlamyphorus truncatus) is reduced. In addition, Priodontes maximus is still hunted for meat in some areas even though it is protected in Brazil, Colombia, Peru, and Suriname. Conservation efforts are planned to breed P. maximus in captivity to help protect the species.
Armadillos are quick and hard to catch, but when caught and cooked, they are considered a delicacy in many parts of Latin America. Hunting is listed as the main cause for the IUCN "Vulnerable" classification of giant armadillos (Priodontes maximus).
Dasypodids have a well-developed sense of smell and hearing. Vision, however, varies with species; some species have adequate and others have poor vision. Poor vision may be associated with the nocturnal or crepuscular behavior of most species. Armadillos tend to have acute hearing and are able to pick up and react to certain noises that signify potential danger. However, some species, such as Dasypus novemcinctus, tend to ignore even threatening sounds if they are busy foraging. All species of Dasypodidae use their acute sense of smell to find other individuals (such as potential mates), their burrows, prey, or predators. Their taste buds and sense of taste are not well developed.
Armadillos communicate mainly through sound and smell. They release secretions from glands within skin pouches, located on different areas of their bodies. These secretions are used to mark their burrows and identify other individuals, such as potential mates or offspring. During estrus, female nine-banded armadillos (D. novemcinctus) produce a secretion near the anus indicating that she is receptive to mating. Six-banded armadillos (Euphractus sexcinctus) mark their burrows by secreting a foul-smelling substance from yellow glands located on their pelvic shields.
Members of Dasypodidae are able to produce several forms of vocalizations. While foraging for food, some species produce a muffled grunting sound. Male and female nine-banded armadillos (D. novemcinctus) let out a “chucking” sound while in their mating pairs. Also within this species, mothers and their offspring softly buzz to one another. When startled, some species of Dasypodidae scream or growl. Greater fairy armadillos (Calyptophractus retusus) are able to create an unusual sound similar to that of a crying human baby.
Communication Channels: acoustic ; chemical
Other Communication Modes: scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Most species of Dasypodidae are polygynous. Males and females of some species engage in courtship prior to mating. The best accounts of courtship are documented for nine-banded armadillos (Dasypus novemcinctus) and, to a lesser extent, southern three-banded armadillos (Tolypeutes matacus).
Male and female D. novemcinctus pair when the female is in estrus. Males of this species pair with 1 to 3 females in a single breeding season, while females pair with only 1 to 2 males. Mate pairings last anywhere from 1 to 4.5 months. Breeding male members of the species maintain prime living territory through aggression.
In D. novemcinctus, the male member of a mating pair forages with the female for several days prior to mating. Periodically, the male attempts to mount the female, or touches her back with his claws, causing her to lift her tail. Once she lifts her tail, the male sniffs her anal region to detect changes in anal secretions that indicate her sexual interest. When she is sexually receptive, the female lies flat on the ground as the male sniffs and licks the area near her anus. In order to mate, the female must flip onto her back so the male can mount her without her dorsal armor getting in the way. The male scratches at the female’s dorsal armor and continues to lick and scratch near the anus until the female fully turns over. Copulation lasts anywhere from 3 to 15 minutes.
Southern three-banded armadillos (T. matacus) also form mating pairs during the breeding season, though the duration of this pairing is not known. Prior to copulation, the male softly touches the female’s dorsal armor to assess her sexual receptiveness.
Six-banded armadillos (Euphractus sexcinctus) in captivity do not display mate-pairing behavior. Instead, males and females randomly meet while foraging, nuzzle, and then mate. Males and females do not closely associate before or after periods of copulation.
Mating System: polygynous
Armadillos are dioecious, iteroparous, and viviparous. The age at which males and females become sexually mature varies with species. Male and female large hairy armadillos (Chaetophractus villosus) reach sexual maturity after 9 months of age. Male Dasypus novemcinctus become sexually mature about 6 months after birth, while females become sexually mature after about 1 year. Male and female giant armadillos (Priodontes maximus) and Pichi armadillos (Zaedyus pichiy) reach sexual maturity between 9 and 12 months of age.
The breeding season for most species of Dasypodidae begins during the spring and summer months, between April and June. Some species in captivity are able to breed anytime throughout the year. Gestation period also varies with species. For individuals of the genus Dasypus, gestation is extended due to embryonic diapause. Embryonic diapause is a delay in embryo implantation that lasts anywhere from 4 months to 2 years depending on the species. This delay is advantageous, as it allows a female to give birth during times of seasonal and environmental prosperity, when chances of offspring survival are greater.
In most species, female armadillos produce a litter of 1 to 3 offspring, usually born between the months of February and July. However, species of the genus Dasypus undergo a process called monozygotic polyembryony, in which 1 egg produces between 2 and 12 identical embryos depending on the species. All offspring born from this process are the same sex.
Gestation period and litter size vary with species. Small hairy armadillos (Chaetophractus vellerosus) have a gestation period of about 65 days and give birth to 1 to 2 offspring. Large hairy armadillos (Chaetophractus villosus) are unique in that they are able to give birth more than once a year, producing 1 to 2 offspring in each litter. The gestation period of C. villosus is 60 to 75 days. Giant armadillos (Priodontes maximus) have a gestation period of about 4 months and produce 1 or 2 offspring per year. Southern three-banded armadillos (Tolypeutes matacus) produce 1 offspring per breeding season, though timing of gestation is unknown. Six-banded armadillos (Euphractus sexcinctus) produce 1 to 3 offspring after a gestation period of about 60 days. Pichi armadillos (Zaedyus pichiy) have a gestation period of about 60 days, after which 1 to 3 offspring are born. Data on litter size and gestation period for most other species are not yet available.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous ; delayed implantation ; embryonic diapause
Depending on the species, armadillos are precocial or altricial. Juvenile nine-banded armadillos (Dasypus novemcinctus) weigh 28.6 to 114 grams at birth, are born with their eyes open and able to walk fairly quickly. Newborns of this species possess pink leathery skin. After several days, the skin solidifies to form the dorsal armor. About 20 days after birth, D. novemcinctus move around outside of their nests, and within 2 to 3 weeks, they are able to leave the burrow for short periods of time. Weaning occurs 4 to 5 months after birth. Males of this species do not provide care to their offspring.
Southern three-banded armadillos (Tolypeutes matacus) also produce precocial young. Newborns are very similar in appearance to adults. Newborns weigh on average 113 g, possess developed claws, and have scute marks. Their eyes remain closed, and they are unable to hear for the first 3 to 4 weeks of life. On the day their are born, however, they are able roll into the protective sphere that is characteristic of the species.
Some species, such as giant armadillos (Priodontes maximus), possess a thick skin at birth but are blind and need their mother's help in order to survive. Weaning in this species occurs between 4 and 5 months after birth. Weaning times known for other species are estimated to be about 6 weeks (Zaedyus pichiy), and 7 to 8 weeks (Chaetophractus vellerosus).
A high level of female parental investment is noted among six-banded armadillos (Euphractus sexcinctus). Newborns are soft and vulnerable at birth. Mothers are extremely protective of their offspring, and if they sense a threat, they become aggressive. Mothers may pick up their young and move them to a safer burrow, if necessary.
Parental Investment: altricial ; precocial ; female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female); pre-independence (Provisioning: Female, Protecting: Female); post-independence association with parents; extended period of juvenile learning
The family Dasypodidae, the armadillos, includes 21 species placed in 8 genera, all found only in the New World (the 21st armadillo species to be recognized, Dasypus yepesi, was described only in 1995 from the Gran Chaco of Paraguay and northern Argentina). Armadillos occur from the southern United States to the Straits of Magellan. Only the Nine-banded Armadillo (D. novemcinctus) reaches as far north as the United States.
The dorsal surface of an armadillo's body is covered with bony plates that protect the head, back, and sides and sometimes the legs and tail. Around the center of the body this armor is arranged into bands of plates separated by soft skin, allowing the animal to bend its body (the number of bands is often a useful character in distinguishing armadillo species). The back is smoothly rounded and the legs are short and powerful, with strong claws on the toes. There are three to five toes on the forefeet and five on the hindfeet. The belly is soft and naked. Most species have little or no hair, but one montane species has dense hair covering the armor.
Armadillos are generally termite and ant specialists (although other animal and even plant food is consumed as well). All species apparently sleep and raise their young in burrows they dig themselves, each species building a burrow with a characteristic size and shape. An armadillo burrow can be recognized by its smooth dome-shaped roof. The litter size is 1 to 12 young.
Head and body length among armadillo species ranges from around 125 to 1000 mm and tail length from 25 to 500 mm. The Giant Armadillo (Priodontes maximus) may weigh as much as 60 kg, whereas the little known Pink Fairy Armadillo (Chlamyphorus truncatus) and Chacoan fairy armadillo (Calyptophractus retusus), which are both thoroughly adapted to a subterranean lifestyle, weigh only around 100 g (Delsuc et al. 2012 and references therein). Armadillos have small ears. The snout, which encloses a long protrusible tongue, varies considerably in length and all species have very reduced peglike dentition, with no incisors or canines.
Armadillos generally inhabit open areas such as savannahs and pampas, but they also occur in forests (four genera and eight species are found in lowland rainforest). They travel singly, in pairs, or occasionally in small groups and may be diurnal or nocturnal. Armadillos can run surprisingly rapidly. Armadillos in a few species may roll themselves into a ball when threatened.
(Emmons 1990; Nowak 1991)
The Nine-banded Armadillo has been the focus of much research on polyembryony. Polyembryony, the production of two or more embryos from a single zygote (fertilized egg), occurs sporadically in diverse animal taxa (including humans). Among the vertebrates, only armadillos of the genus Dasypus are known to utilize polyembrony as their standard reproductive mode. Each litter is typically a set of four identical quadruplets derived from a single fertilized egg. (Prodohl et al. 1996; Loughry 1998)
In the 1970s it was discovered that Nine-banded Armadillos could contract leprosy and since then armadillos have been the primary animal model in leprosy research. Genetic and other studies haverevealed that, although leprosy was absent from the New World prior to European colonization, leprosy now occurs naturally in New World armadillo populations (with a prevalence exceeding 20% in some populations). Infected armadillos have been reported in Alabama, Arkansas, Louisiana, Mississippi, Texas, and Mexico. Although the United States sees only around 150 new cases of human leprosy each year, and two thirds of these are in people who have traveled to regions with endemic leprosy, around 50 cases a year appear to have been contracted within the U.S., often in Texas or Louisiana. Truman et al. (2011) found that a high percentage of unrelated leprosy cases in the southern United States involve infection with the same unique strain of the responsible bacterium, Mycobacterium leprae, that occurs naturally among wild armadillos in the region. These armadillos thus appear to represent a large natural reservoir for M. leprae. However, high prevalence rates among armadillos have been observed in only parts of the southern United States, mainly in the western Gulf Coast states. (Truman et al. 2011 and references therein)
Nine-banded Armadillos apparently crossed the Rio Grande into southeastern Texas some time in the 1820s.In contrast, the eastern population apparently originated from a separate introduction of armadillos into south-central Florida in the 1920s, which subsequently expanded and has only relatively recently merged with the main U.S. population. The extent to which leprosy will become established in eastern armadillo populations remains to be seen. In humans, susceptibility to leprosy appears to depend on multiple genes and the majority of people appear to be naturally immune to M. leprae infection, somewhat moderating the risk to the general human population, although extensive contact with or consumption of armadillos is not recommended. (Loughry et al. 2009 and references therein; Truman et al. 2011 and references therein)
Dasypodidae is a family of mostly extinct genera of armadillos. One genus, Dasypus, is extant, with at least seven living species.
Below is a taxonomy of armadillos in this family.
Family Dasypodidae
Dasypodidae, like Chlamyphoridae, is a basal clade within Cinglata, as shown below. D. kappleri is basal within Dasypodidae.
Cladogram of Cingulata[1][2][3] Cingulata Dasypodidae Dasypus D. (Hyperoambon) D. (Dasypus) ChlamyphoridaeDasypodidae is a family of mostly extinct genera of armadillos. One genus, Dasypus, is extant, with at least seven living species.
