The other types are covered with too many bony plates to allow them to curl up. Other armadillos have to rely on their armored shells for defense while they scuttle away through thick, thorny brush or dig themselves a hole to hide in. Armadillos are used in leprosy research because their body temperatures are low enough for them to contract the most virulent form of the disease.
Armadillos like to swim, and they are very good at it.
They have a strong dog paddle, and can even go quite a distance underwater, walking along the bottom of streams and ponds. When they need to float, they gulp air into their intestines to make them more buoyant. Since they primarily eat insects, they don't have to do a lot of heavy chewing, making big, strong teeth a waste of energy to grow. Like most insect eating mammals, armadillos have a very long, sticky tongue to slurp up bugs as quickly as possible. They also are equipped with strong claws to tear open ant nests.