Rare 'Virgin Birth' Is One Of Few Known Occurrences
POSTED: 8:03 a.m. EDT September 20, 2002
http://www.thekcrachannel.com/news/1678206/detail.html
DETROIT -- Experts are reportedly scratching their heads over the unexpected births of three baby sharks at a Detroit aquarium.
The shark at the Belle Isle Aquarium are trying to figure out how one of their sharks got pregnant with no male shark around.
A white spotted
bamboo shark hatched several eggs, but had not mated with a male shark, according to officials at the facility. The shark was in a tank with another female shark.
"We think it is a case of parthogenesis, virgin birth," said Doug Sweet, curator of fishes.
Zoo and aquarium officials across the nation are trying to figure out what happened.
They think it may be something genetic in the shark triggered in females when no males are around.
The Detroit Free Press reports the rare "virgin birth" is one of a few known occurrences at an accredited U.S. zoo or aquarium. Genetic testing will be done to see if the births can be explained.
Officials say it's possible, though unlikely, that the shark was impregnated before arriving at the aquarium. But the female shark that gave birth hasn't been near a male shark in at least six years. Another possibility is that the mother could have both male and female reproductive characteristics.
The most likely scenario, though thought to be very rare, is that the shark somehow stimulated the eggs without sperm. This complex process, known as parthenogenesis, is very common in snails and water fleas, but becomes more unusual in higher vertebrates.
Zoo officials said that the female bamboo sharks have laid eggs in the past and the development is not unexpected because many animals will lay infertile eggs even if there is not a male to mate with. Those eggs are "assumed to be inviable and are discarded."
But this is the first time in the Belle Isle Aquarium's history that the eggs have hatched and only the second time such a phenomenon has occurred at an accredited zoo or aquarium, according to zoo officials.
A similar event happened last year at the Henry Doorly Zoo in Omaha, Neb. There, a female bonnethead shark, with no male around, gave birth to a baby shark. The birth was the first to raise suspicions that sharks may be able to reproduce parthenogenetically.
Sweet said he hopes the zoo's research will provide new information on the white spotted bamboo shark's reproduction process.
