A stingray in the United States is pregnant – despite not having shared a tank with a male of its species in at least eight years.
Charlotte, who has spent much of her life at the Aquarium and Shark Lab in Hendersonville, North Carolina, is expected to give birth to up to four pups in the next two weeks.
Experts said it would have been impossible for her to mate with any of the five small sharks that share her tank.
The cause is parthenogenesis – a rare form of asexual reproduction in which unfertilized eggs develop into offspring, which can occur in some insects, fish, amphibians, birds and reptiles, but not in mammals.
A woman's egg fuses with another cell, triggering cell division and leading to the creation of an embryo.
Charlotte, who has spent much of her life at the Aquarium and Shark Lab in Hendersonville, North Carolina, is expected to give birth to up to four pups in the next two weeks
One scientist said: “We should make it clear that there is no shark-ray shenanigans happening here.”
Documented examples include California condors, Komodo dragons and yellow-bellied water snakes.
Kady Lyons, a researcher at the Georgia Aquarium in Atlanta, said Charlotte's pregnancy was the only documented example of round stingrays she knew of, although other species of sharks, rays and rays have had such pregnancies in human care.
“I’m not surprised because nature finds a way to make this happen,” she said.
“We don't know why this happens.” Just that it's a really neat phenomenon that they seem to be capable of.
“We should make it clear that there is no shark-ray shenanigans here.”
Charlotte lives in a tank that holds approximately 2,200 gallons.
Brenda Ramer, executive director of the lab, which encourages children to become interested in science, said they hope to get a pool nearly twice the size to accommodate their offspring and install live cameras.
She said lab staff first thought Charlotte had a tumor when they noticed a lump on her back that “bloated up like a biscuit” before an ultrasound revealed the pregnancy.
Lab staff first thought Charlotte had a tumor when they noticed a lump on her back that “bloated like a biscuit” before an ultrasound revealed the pregnancy
Ms Ramer said: “We all thought, 'Shut the back door.' 'There's no way'.
“We thought we were overfeeding them. But we overfed her because she had more mouths to feed.
“It's very rare. But it's happening in the middle of the Blue Ridge Mountains in rural North Carolina, hundreds of miles from the ocean.”