Stingray’s Unusual Pregnancy Without Male Mate Raises Questions, Aquarium Staff Suspect Shark’s Role

A stingray kept inside a North Carolina aquarium is pregnant and the aquarium staff believe that it could have been impregnated by a shark as there are no male stingrays in the tank where she was kept. The stingray, named Charlotte, is kept inside an aquarium inside a shark lab in Hendersonville and will give birth any day now but the news of the pregnancy shocked the staffers and the researchers.

The researchers from the Aquarium and Shark Lab by Team ECCO first saw the swelling in Charlotte back in September and thought it was due to cancer. But once they performed ultrasounds on Charlotte, they realised she was pregnant with multiple pups. “We have been doing ultrasound on our ray, Charlotte, since September, when she began to swell. We documented multiple ‘growths’ internally and initially thought she had a cancer,” a staff member was quoted as saying by UK-based newspaper The Daily Mail.

The report said that there could be two possible explanations behind the mystery pregnancy. According to Rob Jones, the aquarium vet, one reason behind the pregnancy could be ‘parthenogenesis’. Parthenogenesis occurs when eggs develop on their own without fertilisation and create a clone of the mother.

The staff also offered another explanation for the pregnancy. They think that the female stingray could have been impregnated by one of the male one-year-old sharks they placed in her tank last year. They said that they moved two 1-year-old white spot bamboo sharks.

“In mid-July 2023, we moved two 1-year-old white spot bamboo males (sharks) into that tank. There was nothing we could find definitively about their maturation rate, so we did not think there would be an issue. We started to notice bite marks on Charlotte, but saw other fish nipping at her, so we moved fish, but the biting continued,” a staff member, who goes by the name Ramer, was quoted as saying by The Daily Mail.

Bite marks are an indicator of mating in sharks because sharks are known to bite during the mating process. The employee said Charlotte had several bites on her fin edges.

The stingray is carrying up to four pups and was expected to give birth last week but the births are yet to take place. Once the pups are born, DNA testing will take place on the pups to determine if they are mixed breed or clones of their mother.

Stingrays are closely related to sharks and belong to a group of fish called Elasmobranchs. Stingrays have no bones and their skeleton is instead made up of flexible cartilage. They are ovoviviparous which means the offspring hatched from the eggs are held within the body.

Stingrays are mostly solitary animals and come together for breeding and migration purposes.