A shark held with no male counterpart at Detroit’s Belle Isle Aquarium for the past six years has produced three babies in what zoo officials are calling “virgin births.”

The first two offspring hatched in July and the third was born earlier this week, Doug Sweet, curator of fishes at the aquarium, said in an interview on Friday.

The female trio and their two-feet-long mother, a white spotted bamboo shark common to waters in the South Pacific, are all doing well and a fourth offspring is expected in another couple of weeks

“With fish, amphibians and reptiles it does happen sometimes, it is kind of rare but it can happen,” Sweet said of the unusual hatchings.

He said they were thought to be the result of a process called parthenogenesis, which is the ability of unfertilized eggs to develop into embryos without sperm.

“The other option here is that perhaps there’s a chance that the female might be a self-fertilizing hermaphrodite. That is, she might have testicular tissue inside her as well as ovarian tissue, and it’s possible she could be fertilizing her own eggs. Either way you look at it it’s pretty weird,” Sweet said. He said the only other adult bamboo shark in the 680-gallon tank where the mother is held is also a female.

“There’s no male around and there hasn’t been any male around for as long as we’ve had the sharks, and we’ve had them for over six years,” Sweet said. Though the births in Detroit were thought to be extremely rare, Sweet said a bonnet head shark, also held without any male companion, reproduced in late 2001 at a zoo in Omaha, Nebraska.

Unlike the biblical account of Jesus’ birth and the Virgin Mary, “in nature, during parthenogenesis, it typically is always a female that is produced,” Sweet said.