Staff at an aquarium in North Carolina were left confused after a stingray became pregnant despite there not being a male in her tank.
Scientists have a few theories about how this might have happened — and one involves a male shark.
The Aquarium and Shark Lab in Hendersonville, Tennessee was concerned when the stingray began to grow. The executive director of the laboratory wrote that an ultrasound revealed the eggs.
The director, April Smith, said that one possible explanation was parthenogenesis, a process in which a female can produce an embryo asexually without an egg being fertilized with sperm.
She explained that parthenogenesis is a mechanism for preserving species in places where there are no males, like in an aquarium, zoo and even in the depths of the ocean.
However, scientists developed another theory when they noticed bite marks on the stingray. The stingray had been sharing her tank with two white-spot bamboo male sharks.
“Then, our lightbulb went on — sharks bite in order to mate. Did one of the young males mat with her?” Smith wrote.
She said that the most recent ultrasound revealed that the stingray was pregnant with two, possibly three pups.
She explained that their theory would need to be confirmed after the birth unless they first found any visual clues about a mixed breed.
Sharks and stingrays are closely related taxonomically, so interbreeding is theoretically possible.
The animal is due to give birth any day now, and Smith said that updates would be posted on their website and Facebook page.