Nine-banded Armadillo - Anatomy

Anatomy

Nine-banded armadillos generally weigh from 2.5–6.5 kg (5.5–14 lb), though the largest specimens can scale up to 10 kg (22 lb). They are one of the largest species of armadillo. Head and body length is 38–58 cm (15–23 in), which combines with the 26–53 cm (10–21 in) tail, for a total length of 64–107 cm (25–42 in). They stand 15–25 cm (5.9–9.8 in) tall at the top of the shell. The outer shell is composed of ossified dermal scutes covered by nonoverlapping, keratinized epidermal scales, which are connected by flexible bands of skin. This armor covers the back, sides, head, tail, and outside surfaces of the legs. The underside of the body and the inner surfaces of the legs have no armored protection. Instead, they are covered by tough skin and a layer of coarse hair. The vertebrae are specially modified to attach to the carapace. The claws on the middle toes of the forefeet are elongated for digging, though not to the same degree as those of the much larger giant armadillo of South America. Their low metabolic rate and poor thermoregulation make them best suited for semitropical environments. Unlike the South American three-banded armadillos, the nine-banded armadillo cannot roll itself into a ball. It is, however, capable of floating across rivers by inflating its intestines, or by sinking and running across riverbeds. The second is possible due to its ability to hold its breath for up to six minutes, an adaptation originally developed for allowing the animal to keep its snout submerged in soil for extended periods while foraging. Although nine is the typical number of bands on the nine-banded armadillo, the actual number varies by geographic range. Armadillos possess the teeth typical of all sloths, and anteaters. The teeth are all small, peg-like molars with open roots and no enamel. Incisors do form in the embryos, but quickly degenerate and are usually absent by birth.