Shark pregnancy baffles aquarium

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Veterinarian Bob George sliced open the dead shark and saw the outline of a fish.

No surprise there, since sharks digest their food slowly.

Then George realized he wasn’t looking at the stomach of the blacktip reef shark, but at her uterus. In it was a perfectly formed, 10-inch-long shark pup that was almost ready to be born.

George was dumbfounded.

He had been examining the shark, Tidbit, to figure out why she reacted badly to routine sedatives during a physical and died, hours after biting an aquarium curator on the shin. Now there was a bigger mystery: How did Tidbit get pregnant?

“We must have had hanky panky” in the shark tank, he thought.

But sharks only breed with sharks of the same species, and there were no male blacktip reef sharks at the Virginia Aquarium & Marine Science Center in Virginia Beach.

Could Tidbit have defied nature, resulting in the first known shark hybrid?

The other possibility was that Tidbit had conceived without needing a male at all.

A recent study had documented the first confirmed case of asexual reproduction, or parthenogenesis, among sharks: a pup born at a Nebraska zoo came from an egg that developed in a female shark without sperm from a male.

One of the scientists who worked on that study contacted the aquarium, which sent him tissue samples from Tidbit and her pup for testing. If the pup’s DNA turns out to contain no contribution from a male shark, this would be the second known case of shark parthenogenesis.

George hopes to receive a preliminary report soon, but conclusive results could take months.

Tidbit had lived at the aquarium for most of her 10 years, swimming with other sharks in a 300,000-gallon tank.

[Via CNN]