What type of Armadillo curls up into a ball when threatened by predators?

Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order "Cingulata". All species are native to the Americas, where they inhabit a variety of different environments. Armadillos are characterized by a leathery armor shell and long, sharp claws for digging. They have short legs but can move quite quickly.

The armor is formed by plates of dermal bone covered in relatively small overlapping epidermal scales called "scutes" which are composed of keratin. Only the South American three-banded armadillos ("Tolypeutes") rely heavily on their armor for protection. When threatened by a predator, the three-banded ones frequently roll up into a ball. Other armadillo species cannot roll up because they have too many plates.