A zebra shark has produced babies by "virgin birth" four years in a row

Zebedee is a captive zebra shark in the Burj aAl Arab hotel's aquarium in Dubai. It has never met a male shark in its entire life, and yet for the last four years it has successfully, miraculously produced healthy offspring.

This shark is displaying parthenogenesis, which literally means virgin birth. In parthenogenesis, embryos develop without being fertilized. While all Zebedee's parthogenic children must be female, they aren't clones of their mother as their genes are mixed and recombined in the reproductive process.

Many invertebrate species and a variety of vertebrates (of which sharks are one, if they don't technically have a backbone anymore) engage in parthenogenesis, though this is an extremely rare phenomenon in sharks, and had only been observed in captivity a couple times before. This discovery is particularly exciting because Zebedee has successfully given birth to healthy partogenic offspring on four different occasions, which has never been seen before in sharks.

David Robinson, the assistant operations manager at the aquarium, explains that the staff had initially assumed Zebedee was simply laying empty eggs, as there had been no male to fertilize them. But then they made a remarkable discovery:

We were actually moving the eggs and one of the guys felt something move inside the egg. And we checked the eggs with light and there were babies inside. So, it was actually quite, I don't know...we went looking for it, but I don't think we were ever expecting to find it. So we're just awestruck.

Warren Baverstock, the aquarium's curator, says that it's likely other captive shark species possessed this ability all along, but it was simply assumed that the eggs they laid were duds. This ability to reproduce even in the complete absence of males is likely another example of the remarkable evolutionary toolkit that the various shark species possess. It's also another way in which sharks are completely unstoppable, invincible killing machines, but I suppose that's a somewhat less scientific piece of analysis.

For more, check out this BBC News report. Image of zebra shark by ichtheostega on Flickr.