There are two theories circulating on how the females became pregnant – one is parthenogenesis, which means an embryo can develop without male fertilisation.
“So it’s a pretty rare reproductive strategy that they’ve got that rays are able to do,” she told Morning Report.
“And the other theory that we’ve got is that they’re actually able to store sperm. So we did have a male in the tank about three years ago and it’s possible that the two females would have been storing that sperm in their reproductive organs ready for when they decided the time was right to give birth which interestingly was within about five minutes of each other.” “Mystery over birth of eagle ray pups at aquarium” at RNZ
Apparently, there were eleven pups.
Eagle ray maternity: