Turtle embryos can determine their own sex while developing in the egg by moving around to change their temperature, Chinese-Australian research said on Friday.

[File Photo: IC]

By monitoring clutches of turtle eggs, scientists from the Chinese Academy of Sciences and Australia's Macquarie University showed that not only does temperature determine the sex of turtle hatchlings, the embryos actually shift within the eggs to change their own outcome.

"We previously demonstrated that reptile embryos could move around within their egg for thermoregulation, so we were curious about whether this could affect their sex determination," said Professor Du Weiguo from the Chinese Academy of Sciences.

In most turtle species, eggs exposed to high temperatures are more likely to be female and eggs exposed to cooler temperatures are more likely to be male.

"The most exciting thing is that a tiny embryo can influence its own sex by moving within the egg," Du said.

To conduct the study, Du and his team administered the chemical, capsazepine, to some of the embryos, which has the effect of blocking their temperature sensors.

In those embryos which were no longer able to effectively adjust their own temperature, they developed as either all females or all males, depending on the incubation temperatures.

However, those which were not given the chemical and able to move freely around their eggs to determine the temperature, emerged as roughly half male and half female.

The dramatic effect of temperature on turtle embryos has raised concerns about the effects of global warming, with reports last year showing that around 99 percent of turtles born in the warmer regions of Australia's Great Barrier Reef were female.

"The embryo's control over its own sex may not be enough to protect it from the much more rapid climate change currently being caused by human activities, which is predicted to cause severe female-biased populations," Du said.

"However, the discovery of this surprising level of control in such a tiny organism suggests that in at least some cases, evolution has conferred an ability to deal with such challenges."