The marine biologists at Australia's Oceanworld Manly aquarium may be well-versed in the facts of life, but it's never too late to learn a bit more about how exactly babies are made. Recently, twelve healthy baby stingrays were birthed at the facility by a pair of females, much to the confusion of aquarium staff. What's so puzzling about that? Well, the new mothers haven't had any contact with a male stingray for over two years.
Researchers point out that some female marine animals, like rays and sharks, have been known to store sperm until just the right moment to conceive. But, according to a report from Australia's Daily Telegraph, never before have biologists observed stingrays put off starting a family so long after the initial reproductive deed was done. In fact, pregnancy was the last thing on their minds when they noticed two of their rays were starting to plump up.
"We had seen the females were obviously bloated and because of the lack of males we assumed it was a digestive problem or a tumour," the aquarium's life sciences manager Rob Townsend said.
Staff monitored the eagle rays closely but were shocked a few weeks ago when five pups were born to one of the rays, and seven to the other only two days later. It is believed the two females used a storage strategy in which they held sperm in their reproductive tracts and waited for the right conditions to produce offspring.
Townsend later added that the phenomenon "probably happens in the wild all the time" but they just "haven't seen it in captivity."
There's no telling why the two stingrays decided to wait so long after their last encounter with a male to actually produce their offspring -- but aquarium staff are quite delighted that they finally did, and so are visitors. "They've become one of the star attractions of the exhibit that they are in," said Townsend of the baby stingrays.
After all, sometimes the best things in life are worth waiting for.