Armadillos are recognized worldwide for their unique bony armor, the carapace, which distinguishes them from nearly all other mammals. This protective covering serves as a flexible shield against predators and environmental hazards. While the armor is entirely present at birth, it is structurally different from the adult shell.
The State of the Carapace at Birth
The armor of a newborn armadillo is fully formed but lacks the rigidity associated with the adult carapace. Rather than a hard shell, the pup is born with a soft, pliable covering that feels leathery and has a pinkish or pale grey coloration. This covering is noticeably soft to the touch, often compared in texture to a human fingernail.
The underlying structure of the adult armor, composed of bony plates called osteoderms, is already in place beneath the skin. These plates, however, are not yet calcified or fused together, which is why the shell remains flexible at this stage. This pliability is necessary for the pup’s development, allowing it to grow rapidly and navigate the confined spaces of the burrow and the birthing process itself. The young armadillo is born in a relatively advanced state of development, with its eyes open, and this soft armor facilitates early movement.
The Process of Shell Hardening
The transformation from a soft, leathery covering to the rigid adult shell is a gradual biological process involving ossification and calcification. Ossification is the process of bone formation, where the soft tissue of the osteoderms becomes true bone. Calcification involves the deposition of calcium salts and other minerals into this developing bone tissue, giving the armor its characteristic hardness and strength.
This hardening is directly tied to the pup’s nutrition as it nurses, requiring an intake of calcium and other minerals for bone growth. The pinkish color of the newborn’s shell begins to darken to the brown of the adult within the first few months, a visible sign of the structural change. The shell will continue to gain strength throughout the juvenile period, becoming fully rigid and reaching its adult texture within a few weeks to several months after birth.
Early Life and Development of Armadillo Pups
Armadillo pups are born in an advanced state, closely resembling smaller versions of the adults, though they are initially unsteady on their legs. For the common Nine-banded Armadillo, the female almost always gives birth to a litter of four genetically identical quadruplets, all of the same sex, which develop from a single fertilized egg. Newborns typically weigh between 50 and 150 grams and are about 25 to 30 centimeters in length from nose to tail tip.
The young remain within the natal burrow, relying entirely on their mother’s care and milk for several weeks. They begin to venture outside the burrow to forage alongside their mother at about one month of age. The pups will continue to nurse for approximately two to three months, but they begin to shift their diet to solid foods, such as insects and invertebrates, around three to four weeks old. This transition from milk to a foraging diet marks a significant step toward independence and full physical maturity.