Crocodile makes herself pregnant in first case of reptile ‘virgin birth’

Scientists believe that crocodiles may have been secretly self-spawning for eons. Photo / Getty Images

A crocodile has made herself pregnant in what is the first recorded example of a “virgin birth” in the species.

The reptile was kept in captivity in a zoo in Costa Rica and had no contact with any male crocodiles, but a fully formed foetus was found inside one of her eggs.

The developing reptile was 99.9 per cent genetically identical to its mother, which proves it had no father.

Scientists said the capability could have been inherited from dinosaurs, which may also have been able to reproduce by themselves and are close relatives of crocodiles.

There are documented examples of virgin births, or parthenogenesis, in snakes, lizards and fish. But this is the first proven example of it in crocodiles.

The crocodile laid several eggs in 2018 when she was 18 years old. Seven were incubated but after none hatched for three months they were opened, revealing the stillborn foetus in one of the eggs.

Virginia Tech researchers, who analysed the foetus, said their findings suggested crocodiles could be having virgin births without anyone realising.

Because parthenogenesis can occur even when potential mates are present, other examples of virgin births may have been missed in the past, they said.

“It is not uncommon for captive reptiles to lay clutches of eggs, given the period of isolation from mates, these would normally be considered non-viable and discarded. These findings, therefore, suggest that eggs should be assessed for potential viability when males are absent,” the scientists said in their paper published in the Royal Society journal Biology Letters.

“This new evidence offers tantalising insights into the possible reproductive capabilities of extinct relatives of crocodiles,” they added, “notably the dinosaurs”.

Experts believe that ability for animals to go through parthenogenesis is often hidden or dormant, and happens when numbers of a species plummet and they are on the verge of extinction.