Tuesday, September 18, 2007

Shark gives birth despite lack of mate

Courtesy of The Arizona Republic

By Betty Reid, The Arizona Republic

Students at Carl Hayden Community High School were stunned when a baby shark appeared in one of their fish tanks.

More amazing was that the mother shark had been in the tank alone for nearly four years.
Teacher Fredi Lajvardi and his Phoenix science students investigated and discovered that the birth is rare.

"As far as we know, we are the third case worldwide," Lajvardi said.

This type of birth is known as parthenogenesis, in which an unfertilized egg develops into a new pup, said Lajvardi, program manager for the Carl Hayden Center for Marine Science.

"The mother's gene divides in half and recombines with its own collection of genes to create a new individual," Lajvardi said. "Normally, it would recombine with the father's half of the gene. But because there is no father, the mother provided the other half."

It was a learning moment for students who saw firsthand last week how through parthenogenesis a species can reproduce when a mate isn't present.

The week-old pup, whom students have named Dawn, was born to a white-spotted bamboo shark named Twilight, who has lived in one of the school's marine-science classrooms. .

"When we found out it hatched, everyone rushed the tank," said Kristen Shriner, a 17-year-old senior who has overseen the care of the mother shark.

She and other students have been e-mailing scientists to find out how to properly care for Dawn.

For now, Dawn will remain at the school; outside scientists have been invited to visit.
About 200 students study in the marine center at the high school at 3333 W. Roosevelt St.

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