Crocodile makes herself pregnant
Although it is the first recorded case in a crocodile, other vertebrates are known to reproduce through parthenogenesis.
Researchers have confirmed the first ever recorded case of a female crocodile laying a fertile egg through parthenogenesis.
A new study, published in Biology Letters, revealed that an American crocodile (Crocodylus acutus) in a zoo in Costa Rica laid an egg that contained a fully-formed foetus which was 99.9 per cent genetically identical to the mother.
The female crocodile had had no contact with a male for about 16 years.
The egg was part of a clutch of 14 eggs discovered by zookeepers in January 2018. Seven appeared to be fertile and were artificially incubated.
After the eggs failed to hatch, they were opened to to assess their contents. In one was a fully formed foetus. A DNA test revealed the genetic similarity with the mother.
This form of reproduction, vertebrate facultative parthenogenesis, was once considered rare. But advances in molecular genetics have made it easier to study and improved scientists understanding of the phenomenon.
Parthenogenesis has been reported in species such as Komodo dragons, Burmese pythons and domesticated turkeys.
Captive reptiles have previously been known to lay clutches of eggs, but they have generally been discarded as non-viable. There may therefore have been previous cases of captive crocodiles becoming pregnant in this way which went unnoticed.
Dr Warren Booth, who led the research, told the BBC: “We see it in sharks, birds, snakes and lizards and it is remarkably common and widespread.
“There was a big increase in reports of parthenogenesis when people started keeping pet snakes. But your average reptile keeper doesn't keep a crocodile.”
Veterinary practices are being urged to help owners safely dispose of any unused and expired pet medicines - not just antibiotics - during November's Animal Medicines Amnesty. 
