After saying Charlotte, a lone stingray, was pregnant, aquarium now says she's sick

It was called a miracle pregnancy, a rare case of parthenogenesis. But Charlotte, a round stingray who caused a big stir when her aquarium in Hendersonville, N.C., announced she had become pregnant without the participation of a male ray, is not pregnant after all. "Charlotte has developed a rare reproductive disease that has negatively impacted her reproductive system," says the Aquarium & Shark Lab by Team ECCO, citing recent lab reports. "The findings are truly a sad and unexpected medical development."

Aquarium founder Brenda Ramer released few details about the ray’s condition, but she did confirm to local TV station WLOS that Charlotte is not currently pregnant. As she gave an update, Ramer also pushed back on ideas floated by critics online who have suggested she seized on Charlotte’s possible pregnancy to draw attention to her aquarium. "I can only tell you what we know for certain. I've never been a liar. This was not a scam," Ramer told WLOS. "This was not anything made up, but people do that. People have their own thoughts."

"This is a very weird story," Warren Booth, who studies facultative parthenogenesis, a type of asexual reproduction, and is an associate professor of entomology at Virginia Tech, told NPR.

"The most unusual thing for me is that I recall seeing footage of an ultrasound [which Charlotte had in February], and on that ultrasound you could see an embryonic ray," he said. It makes him wonder, he added, "if the female aborted the developing embryo(s) and either consumed them or a tank mate consumed them."

As months ticked by, questions and concern grew

The ray's pregnancy had been held up as a unique example of asexual reproduction in her species. But then the months passed, and Charlotte reached the expected gestation period for a stingray (from 3 to 4 months).

The aquarium clarified the ray's status shortly after a feature article by North Carolina news outlet The Assembly, which last week highlighted marine experts' concerns for Charlotte's health — and their skepticism over Ramer's suggestion that the ray might have been impregnated by a male shark in her tank — possibly producing a shark-ray hybrid.

Charlotte quickly became a sensation

The ray's story fascinated people far beyond Hendersonville in the mountains of western North Carolina: Soon after the aquarium announced her pregnancy, the town near Asheville started seeing an influx of visitors and tourists. People drove for hours and fueled a line out the door, hoping for a chance to see Charlotte. A downtown café named a latte in the ray's honor, and the town's tourism website saw a huge leap in traffic, as NPR reported. Charlotte's newfound fans waited in anticipation for news of a birth — but when they came, the updates were mainly incremental.

"In weekly video posts," Blue Ridge Public Radio reports, Ramer and the aquarium's staff "provided updates and encouraged the public to be patient, noting there was no data on the gestational timeline."

Why did the aquarium believe Charlotte was pregnant?

"The fact that the vet told me," Ramer said in early February, as she performed a public ultrasound on Charlotte in a streaming Facebook video.

"We thought that she was developing some kind of a cancer when we saw the lump," Ramer said, referring to Charlotte's protruding back. But then, Ramer said, she sent images of the lumps to Robert Jones, a shark and ray expert in Australia, and Beckah Campbell, a doctoral candidate in the shark research lab at Arizona State University.

"They both came back and went, 'Oh no, those are eggs,'" Ramer said.

In the February video, Ramer repeatedly pointed to a small screen for signs of Charlotte's offspring. She described how a tank was being prepared to act as their nursery.

"There's a baby," Ramer said as she pointed to the grainy screen. "That looks like a tail, right there."

The ray pups could be "due to be born any single minute," she said.

But Ramer also acknowledged that her staff had only recently learned how to use the ultrasound machine.

"It's kind of like trying to read Chinese, isn't it?" she said as she gestured at the screen, noting that rays' cartilage makes ultrasound images hard to decipher.

If anyone watching also happened to read ultrasounds for a living, she added, "Please chime in."

What about a shark-ray hybrid?

When she said Charlotte was pregnant, Ramer called it an apparent case of parthenogenesis, a method of asexual reproduction seen in other species of rays and documented in sharks, which are related to rays, Virginia Tech's Booth noted.

"I have been amazed at how much attention parthenogenesis attracts any time it is reported," he said, adding that people seem drawn to stories about an enigmatic vertebrate species reproducing asexually (it's much more common in invertebrates).

"The sad thing is that the babies produced through parthenogenesis rarely survive for long," Booth said. "Given that the parthenogens lack genetic diversity, and are effectively highly inbreed, they are sadly doomed."

But Ramer also raised another possible explanation, one discounted by experts. Ramer said Charlotte might be bearing some kind of shark-ray hybrid. Because while her tank didn't have any male rays, it did have male sharks.

"One day we're kind of like, oh my gosh, sharks bite when they mate," Ramer said. "She had bite marks. There's a potential that she mated with one of these … sharks."

"Either way we have very unique juju going on here," she said, adding that after the pups were born, "we will send all the DNA off and have it all tested, just to see in case we have a whole new species created right here on Main Street."

But the creation of a previously unknown marine hybrid in the Appalachian aquarium was not likely, parthenogenesis expert Booth told NPR in the spring. "It's very unlikely [the ray and a shark] could have hybridized," Booth said. "Even though they're both Elasmobranchs, I think they're so genetically distant that that is not considered possible."

What does the museum say now?

That its main priority is the ray's health.

"We will work with, and be guided by, veterinarians and specialists to better understand this disease and the treatment options for Charlotte," the facility wrote on Facebook.

"While the research of this disease is limited, we hope that Charlotte's case and medical treatment will positively contribute to science and be of benefit to other rays in the future," the aquarium added.

Responding to people asking what disease the ray has contracted, the aquarium said it's trying to learn more, replying, "it is simply found under that text reproductive disease."

The aquarium didn't open on Saturday, citing a need to focus on Charlotte's health.