Its biggest lesson now is on the process of parthenogenesis: a type of asexual reproduction in which offspring develop from unfertilized eggs, meaning there is no genetic contribution by a male.

The mostly rare phenomenon can occur in some insects, fish, amphibians, birds and reptiles, but not mammals. Documented examples have included California condors, Komodo dragons and yellow-bellied water snakes.

Kady Lyons, a research scientist at the Georgia Aquarium in Atlanta who is not involved with the North Carolina aquarium, said Charlotte's pregnancy is the only documented example she's aware of for this species, round stingrays.

But Lyons isn't at all shocked. Other kinds of sharks, skates and rays—a trio of animals often grouped together—have had these kinds of pregnancies in human care.