Shark Gives "Virgin Birth" in Detroit

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"Fish are known to have the only self-fertilizing hermaphrodite vertebrate species, so I don't rule it out, but again, I think it's unlikely," said Sweet.

Genetic Testing

Genetic testing should provide the answers, but it won't be soon.

The offspring would not be a true clone, said Sweet. "There is some exchange at the chromosomal level, and the genes are reshuffled very slightly, but the DNA match between mother and child should hopefully be very close," he said.

Rick Brenneman, a geneticist at the Henry Doorly Zoo and colleagues have been studying the bonnethead shark suspected to be the result of parthenogenesis since last December.

"To date, finding the genetic markers that will identify mom and dad in sharks in general has been very difficult," he said. It's even more difficult when you suspect there may not be a dad.

The bonnethead shark and bamboo shark are from different families; the bonnethead suspected of a virgin birth gave birth to a live pup, rather than laying eggs as the bamboo shark had. But studying both will almost certainly provide scientists with insights into the genetic make-up of sharks.

"This will be a long term project requiring tenacity and a great deal of effort, but ultimately it should enable us to better understand what it is that allows parthenogenesis, if in fact this is what is occurring, and what the genetic trigger might be," said Brenneman. The genetics lab at Omaha's Henry Doorly Zoo will also conduct the genetic testing of the Belle Isle bamboo sharks.

In the meantime, what about all those eggs that were being thrown away? The two sharks at the Belle Isle Aquarium typically go on an egg-laying spree once or twice a year, laying a clutch of four to six eggs.

"We're definitely holding them now and incubating them," said Sweet. "If you have one parthenogenetic shark, you may as well have a whole tank of them."

National Geographic Shark Resources:

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Jaws Author Peter Benchley Talks Sharks
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South Africa Rethinks Use of Shark Nets
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Are People Eating Sharks Out of Existence?

Shark Sites on
Creature Feature: Great White Sharks
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Shark Surfari: Online Quiz

Related Lesson Plans:
Use this National Geographic News article in your classroom with the Xpeditions lesson plans:

Lesson Plan: A Trip to the Beach
Lesson Plan: Are Sharks As Dangerous As We Think They Are?
Lesson Plan: Does the Hammer Help?
Lesson Plan: Sharks—Setting the Record Straight
Lesson Plan: Sharks—Should They Be Afraid of Us?
Lesson Plan: What's the Hammer For?

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