Biomedical Ephemera, or: A Frog for Your Boils

Nine-Banded Armadillo (Dasypus novemcinctus)

Did you know that the nine-banded armadillo (and a few of its Dasypus cousins) gives birth to identical quadruplets in almost every litter? Shortly after the zygote implants in the uterus, it splits into four (or occasionally three or five) separate embryos, each of which develop their own independent placenta. This means that, unlike in identical human fetuses, blood and nutrients are not shared, and the death of one fetus is unlikely to affect the survival of the others. After the pups are born, they remain in the burrow for approximately three months, and over the next year of their life, slowly wander farther and farther away from their place of birth.

As nine-banded armadillos have few natural predators in their Northern range, this highly effective reproduction strategy means that one female will often produce upwards of 50+ offspring in her relatively short lifetime. Those offspring have been expanding the armadillo’s known range for the past several decades. However, as armadillos are poor at thermoregulation, they’ve just about reached the limit of the area that they can survive in - any farther north, and they would not be able to survive the longer winters.

Images:

Top: Tatusia novem cincta [now Dasypus novemcinctus] - The Nine-Banded Armadillo. From Biologia Centrali-Americana. F. Ducane Godman and Osbert Salvin, 1918.

Bottom: Fetal Nine-banded Armadillo Pups. The American Journal of Anatomy. Vol. III, 1900-1901. “Enamel in the teeth of an edantate.” A. M. Spurgin.