A female stingray who has spent the majority of her life in a North Carolina aquarium, was found to be pregnant after not sharing a tank with a male companion within the past eight years. The pregnancy was announced via a Facebook post on February 6.
The staff at the aquarium noticed Charlotte’s swelling in September. They began doing periodic ultrasound scans on her with the belief that she had a tumor in its early stages. The internal ‘growths’ that they originally found were later confirmed to be eggs by the aquarium vet. Although we are currently past the average three to four month gestation period of a stingray if Charlotte was in fact impregnated in September, scientists believe that this time frame is flexible for stingrays in captivity.
The Aquarium and Shark Lab in Hendersonville, North Carolina is about 2,300 miles from Charlotte’s natural habitat of the coastal Southern California waters. Her pregnancy is not only a surprise due to how far she is from home, but also because the only other male companions in Charlotte’s tank are sharks.
"The unique thing about Charlotte is we do not have a male ray," founder and Executive Director of Team ECCO Brenda Ramer said.
Charlotte is said to be pregnant with about four pups according to the Aquarium’s specialists, and is expected to give birth within the next few days. The possibilities of how Charlotte became pregnant include the rare chance that she mated with a shark, or through parthenogenesis, which is a form of asexual reproduction.
Charlotte has been living with young male sharks since July. Researchers viewed this as a possibility when Charlotte was previously found with bite marks, a sign of shark mating. After Ramer expressed this theory to the press, it was counteracted by other professionals.
“We should set the record straight that there aren't some shark-ray shenanigans happening here," a research scientist at the Georgia Aquarium Kady Lyons said. Lyons claimed that the differences between a shark and stingray’s DNA and size make it nearly impossible for the two species to procreate.
However, the situation is so unique that both methods of impregnation are extremely rare and either possibility cannot be discounted until the babies are born.
Newtown High School Environmental Science and Anatomy teacher Justin Thomas is holding a poll in his classes comparing student’s opinions on how Charlotte became pregnant.
“Regardless of the result, either option is possible but rare so it’d be a first time event especially for that aquarium,” Thomas said.
In addition to the interesting science behind it, Charlotte’s pregnancy has been attracting many online and in-person viewers.
“Anytime you can draw attention to a zoo or aquarium, especially for a younger audience, that’s a good thing,” Thomas said.
Aquariums and organizations that help the welfare of animals have been decreasing in popularity, and events like these draw in visitors and can greatly increase funding.
Currently, Ramer, Lyons, and other scientists are nearly positive that Charlotte’s pregnancy is the result of parthenogenesis. Parthenogenesis is also known as a virgin or miracle birth, and is an extremely rare phenomenon. In this process, small cells are created, separate from the mother’s eggs, and then merge with the egg to form an embryo.
The offspring that are produced from this are genetically similar to the mother but not an exact copy. Parthenogenesis has previously occurred in other sharks, amphibians, and rays but is most often intentionally done by humans.
To prepare for the mysterious birth, the staff at Charlotte’s aquarium are working on transferring her to a larger tank where she and her pups are comfortable.