Armadillos are native to North, Central, and South America. There are over 20 species on Earth, but only one is indigenous to the United States. The armadillo famously curls up into a ball when threatened, using a hard outer shell for protection. Many species of armadillo, including the species in the US, are endangered or threatened due to human encroachment on their habitat. Domesticated dogs and over-hunting have only further increased the threat to the armadillo.