Second Shark Experiences Virgin Birth

A second case of a Shark virgin birth has been reported in the Journal of Fish Biology this Friday. Scientists conducted a DNA test that proved a “pup carried by a female Atlantic blacktip shark in the Virginia Aquarium & Marine Science Center contained no genetic material from a male.” (Associated Press) The first case of such a mysterious event happened to a hammerhead shark at the Omaha, Nebraska zoo back in May of 2007.

“The first case was no fluke", shark scientist Demian Chapman said in a statement. “It is quite possible that this is something female sharks of many species can do on occasion.” Both sharks that reproduced without a mate only carried one “pup” when it’s quite normal for a shark to carry as much as a dozen at a time or more. But scientists warn people to view these kind of rare cases as a sign that sharks are going extinct.

The medical marvel was first discovered 16 months ago when an Atlantic blacktip shark named Tidbit died at the Virginia Beach aquarium. “No blacktip sharks were present during her eight years at the aquarium,” AP reports. The 5-foot, 94-pound shark died from complications related to her “unknown pregnancy” after even undergoing an annual checkup.

The baby shark was found during a necropsy of Tidbit, making staff think the pup was either “a product of a virgin birth or a cross between the blacktip and a male of another shark species – which has never been documented,” Chapman told the press. The female shark’s pup was nearly full term when found, and most likely would have been eaten by the large sand tiger sharks in the tank, which is what happened to the last virgin born baby in Omaha. “By the time they could realize what they were looking at, something munched the baby,” Chapman added. The remains of the pup’s body were used for DNA testing.

Virgin birth has been proven in other animals in the past, such as fish, amphibians, reptiles and birds. Scientists say the 2 shark cases were made possible due to the baby acquiring “one set of chromosomes when the mother’s chromosomes split during egg development, then united anew.” (AP) Due to the absent chromosome only acquired in male sperm, the offspring doesn’t have all the skills needed in order to fully survive in the wild, however. They can be more susceptible to congenital disorders and diseases, among other things. But researchers still know very little about the cause and effect of such rare occurrences.

This case brings home questions scientists have been trying to answer for years about how often asexual births occur in the wild. Mahmood Shivji, a scientist and director of the Guy Harvey Research Institute at Nova Southeastern University in Florida, thinks this may become more and more possible due to “population densities” becoming too low, making it particularly hard for female sharks to find mates.


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