May 23, 2007 -- In 2001, one of the hammerhead sharks in the Henry Doorly Zoo in Omaha, Neb., gave birth to a baby -- and to years of mystery.
"We didn't have a male and had never had a male, and of course, the question was, how did this happen?" said Lee Simmons, director of the Henry Doorly Zoo.
The baby shark's seemingly impossible birth confused everyone. It was born in a tank with three females -- and none of them had even seen a male for at least three years.
"There were really only two possibilities," Simmons said. "One was virgin birth, and the other one was a delayed insemination."
In a study released today, scientists analyzed the baby shark's DNA and found no trace of a male father. The study found that female sharks can fertilize their own eggs and give birth without sperm from males. Some shark experts believe it proves the phenomenon of virgin birth in sharks.
"It's kind of like the immaculate conception for sharks, if you will," said Robert Hueter of the Mote Marine Laboratory. "What happens is that a female is unable to find a mate. Over a period of time, given the right circumstances, her eggs then respond to this and actually mature basically and self-fertilize."
For the zoo's staff, the study provided proof they needed to solve a 6-year-long mystery and silence the skeptics.
"One of the good things about good science is that your skeptics have to eat crow," Simmons said.