A new study from Monash University researchers has found that female turtles have an unique biological ability to delay laying their eggs until conditions are best for their young’s survival.

By studying four species of turtle it was found that due to the low oxygen levels in the reproductive tracts of egg-carrying females, they are able to halt embryonic growth at a certain stage.

The ability to create this low oxygen environment for egg storage explains why live-birth has not evolved in turtles as it has in many other reptile species.