Ray suddenly pregnant – shark under suspicion

In an aquarium in the American state of North Carolina, the “Aquarium & Shark Lab ECCO” in Hendersonville, a mystery currently needs to be solved. As local media reports, a stingray named Charlotte is pregnant, even though no males live in the facility.

Aquarium staff were initially concerned about the swelling Charlotte showed in September, which was feared to be a possible illness such as cancer. But upon further investigation, the true cause was discovered with the help of ultrasound.

Researchers are now talking about two possibilities of how this could have happened: On the one hand, it could be a so-called parthenogenesis or virgin generation – an extremely rare process of unisexual reproduction. The offspring arise from individual unfertilized eggs.

On the other hand, Charlotte may have mated with one of the younger male sharks in the aquarium. Bite marks on Charlotte’s fin edges seem to support this theory. During sex, the male shark often bites the female’s pectoral fins to gain more support. Brenda Ramer, founder and executive director of the aquarium, explained: “We introduced two yearling male white-spotted bamboo sharks to this aquarium in mid-July 2023.” It was not thought that a link could take place.

The normal gestation period for stingrays is usually three to four months. Charlotte is expected to give birth to four cubs soon. The aquarium staff and researchers are equally enthusiastic. To be sure, DNA testing must be done after birth.

Despite their external differences, sharks and rays are closely related and both belong to the group of cartilaginous fish that reproduce by internal fertilization. As scientists report, their mating behavior is also similar – so the possibility of mating between the two fish cannot be ruled out.