Imagine discovering a litter of armadillo babies and finding that every pup is the same sex. It may sound like an unusual coincidence, but for one particular armadillo species, this is actually a remarkable feature of its reproductive biology.
The nine-banded armadillo is known for producing groups of genetically identical offspring, but does this really mean that all the babies in a litter are always the same sex?
VERDICT:
TRUE
For the nine-banded armadillo (Dasypus novemcinctus), babies in a litter are indeed the same sex.
Unlike most mammals, which can produce offspring of different sexes in the same litter, the female nine-banded armadillo typically gives birth to four genetically identical pups. All four are either male or female.
This unusual phenomenon is known as polyembryony. It begins when a single fertilised egg splits into four separate embryos, rather than developing into one individual. Because all four embryos originate from the same fertilised egg, they are genetically identical and therefore the same sex.
The nine-banded armadillo is particularly unusual because this happens routinely. It is the only mammal known to regularly produce identical quadruplets, according to the Guinness World Records.
Research published in the Journal of Experimental Biology also describes the species as producing monozygotic, or identical, quadruplets.
The pups develop together in the womb and share a single placenta. They are born after a period of delayed implantation, a reproductive adaptation in which development of the fertilised egg is temporarily postponed before it attaches to the uterus.
After birth, the young remain in the den with their mother for several weeks before venturing out. They continue to stay with her for several months as they grow and learn to forage.
However, it is important to note that this unusual reproductive pattern does not apply to every armadillo species.
The nine-banded armadillo belongs to the genus Dasypus, several members of which are capable of polyembryony, while other armadillo species generally produce offspring from separate fertilised eggs.
The next time you come across a video showing a litter of armadillo pups that all appear to be the same sex, it may not be an AI trick. For the nine-banded armadillo, this unusual sight is a real result of its remarkable reproductive biology.
References:
1. Understanding Animal Research - Armadillo
2. American Museum of Natural History - Nine-Banded Armadillo
https://www.amnh.org/exhibitions/permanent/north-american-mammals/nine-banded-armadillo
3. Guinness World Records - Most fertile animal for quadruplets
https://www.guinnessworldrecords.com/world-records/73559-most-fertile-animal-for-quadruplets
