Virgin Shark Reproduces

For the second time, marine biologists have found a shark reproducing asexually, or without a mate. The findings were reported in the Journal of Fish Biology, and the claims were backed up with genetic evidence.

David Chapman is a leader in the study and specializes in sharks. "It is quite possible that this is something female sharks of many species can do on occasion," he says. However, all scientists involved in the study stated that from what they have observed in captivity, this is a rare occurrence.

Tidbit was a blacktip shark who lived at the Virginia Aquarium & Marine Science Center, and she never shared a tank with a male shark of her species. When she died and her autopsy was conducted, a fetal shark almost at full term was discovered. Initially it was believed that she had mated with a shark of another species, but DNA analysis proved that theory wrong.

The phenomena of virgin birth has been documented in many types of animals, including bony fish, amphibians, reptiles and birds. Wild sharks are expected to exhibit the behavior as well. While it may be rare now, some scientists such as Mahmood Shivji expect it could become a more common practice in the wild. "It is possible," he says, "that parthenogenesis could become more common in these sharks if population densities become so low that females have trouble finding mates." However, this would be harmful to the population. Without male chromosomal contributions, the gene pool of wild sharks would become less diverse.

Another discovery very similar to this one was made in the Omaha, Nebraska Zoo, and the mother of the asexually produced pup was a hammerhead shark. Unfortunately, the pup was eaten by other sharks in it's tank and did not survive. Only remains were left to use in a DNA analysis, which prevented any observations of a living specimen from being made.