Armadillo Armor

A recent report examines the role that the carapace relates to the lifestyle and evolution of armadillos. The carapace has obvious advantages of protecting against predators and external parasites. . But few traits evolve in isolation, and in the case of armadillos there are other significant effects of having a carapace.

One accompaniment of a carapace is that it limits movement and thus metabolic needs. Thus, their low metabolic rate allows the armadillo to survive on a low quality diet, usually worms and grubs. They can endure the low oxygen content of their burrows and their nose buried in soil as they forage for food. They do need a higher respiratory rate because the carapace limits thoracic expansion and deep breathing.

They have difficulty maintaining the usual mammalian body temperature, which limits their expansion into cold climates.

The carapace would make mating next to impossible were it not for the fact that males have an exceptionally long penis, up to 50% or more of body length in some species. Short lactation periods and rapid infant growth are a necessity for species survival.

Social interactions are limited because so much time must be devoted to food acquisition. Exhaustion of food supply is prevented by having territories of a few acres in which only one individual lives. Their daily activity periods are short (4-6 hrs/day, mostly at night), and most of that is exclusively devoted to foraging.

Superina, M., and Loughry, W. J. (2015). Life on the half-shell: consequences of a carapace in the evolution of armadillos (Xenarthra: Cingulata). J. Mammal. Evol. June. doi 10.1007/s10914-011-9166-x

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