A lone stingray mysteriously became pregnant in an aquarium. Scientists now think a male shark could be responsible.

• A stingray in a North Carolina aquarium became pregnant without a male in the tank.
• Scientists believe that a male shark could be the father.
• Another explanation could be parthenogenesis, in which a female produces asexually.

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 by Team Ecco in Hendersonville was initially concerned that the stingray had cancer when she began to swell. However, an ultrasound later revealed that the growths were eggs, the lab’s executive director wrote in a blog post.