Irish and American scientists, using new techniques, confirmed that a female hammerhead shark at the Henry Doorly Zoo in Nebraska gave birth to a pup in 2001— without having sex. A male tiger shark was suspected to be the father at first, but the team's genetic analysis shows no sign of paternal DNA.
This type of sperm-less conception— known as parthenogenesis— has been encountered in bony fish but never cartilaginous fish. The virgin births could be detrimental to the already endangered shark population, diminishing the genetic diversity that helps them adapt to new environmental conditions and stave off disease. The fatherless pup was killed by a stingray shortly after birth.