Virgin birth suggests a bleak future for hammerhead sharks

A VIRGIN birth has been recorded among hammerhead sharks for the first time, in a discovery that raises concern about wild populations.

A female shark that was caught off Florida as a baby gave birth at Henry Dorley Zoo in Nebraska in December 2001, even though there were no male hammerheads in the aquarium.

Similar births have been recorded before, but these have been put down to the sharks' ability to store sperm for long periods.

However, researchers from the zoo and from Queen's University Belfast, Nova Southeastern University in Florida carried out genetic tests that showed that the newborn shark had DNA only from its mother.

This means it is more at risk of genetic diseases passed on through the female line and raises concern about the genetic health of wild hammerheads.

The lead author of the Royal Society study, Dr Demian Chapman, said the process of conceiving without male sperm, called parthenogenesis, was "probably more common in nature than we think".

"It is very difficult to detect. It's only when you put animals in captivity that you notice these weird births," he said.

"Shark populations are severely depleted. It might be getting to the point where females are having difficulty finding males. Then what could happen is they produce these parthenogenetic offspring."

However the chance of further research has gone - the baby shark is since believed to have been eaten by another animal in the tank.

Komodo dragons, gecko lizards and insects including bees are able to reproduce in this way, but the process is not thought to be possible in mammals, the scientists said.