Aquarium staff, left puzzled after a female stingray became pregnant despite there being no male stingrays present in her tank, think they may have worked out what happened.
Staff at The Aquarium and Shark Lab in North Carolina were initially concerned that Charlotte the stingray had cancer after they noticed some swelling back in September and decided to carry out an ultrasound.
However, they were shocked to discover that the fish was actually pregnant - despite not coming into contact with a male stingray.
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Charlotte is carrying up to four pups and is due to give birth any minute now.
A staff member said: “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.
“I reached out to Dr. Rob Jones, the aquarium vet, and he identified the growths as eggs. We have no male ray. He said there have been few cases of parthenogenesis in rays.”
Parthenogenesis is an unusual and rare phenomenon in which an egg develops without being fertilised, effectively making a clone of its mother.
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But parthenogenesis isn’t the only theory that the experts are considering - as staff believe that Charlotte could have been impregnated by one of the male one-year-old sharks that was placed in the same tank as her back in the summer.
The staff member explained: “In mid-July 2023, we moved two one-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.”
Bite marks can be an indication of mating in sharks, as the fish are known for nipping at each other during the mating season.
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Stingrays are closely related to sharks and are both part of a group of fish called Elasmobranchs - meaning it’s not beyond the realms of possibility that the pair could have mated.
The gestation period in stingrays is usually three to four months, with Charlotte initially tipped to give birth on February 9 - but as of yesterday (February 10) the birth still hadn’t taken place.
Experts from the lab will carry out DNA testing on Charlotte’s offspring when they’re born to determine if they are part shark, part stingray.
Claire Reid