River Murray Turtle embryos from South Australia, can adjust their developmental rate so that all the eggs in a clutch can hatch around the same time, a new study has found. Young turtles face many challenges when they hatch and venture into the world.
Please see Ridley Kemp sea turtles hatching and making way for the sea in video below.)
Hatchlings, as a large group, work together to dig their way out of the nest more easily. And their arrival all at the same time increases their survival chances, as predators are swamped by high numbers of prey.
Scientists investigated incubation and group hatching in the River Murray Turtle. Although the temperature of the nest affects the developmental rate of eggs, researchers discovered another factor that influences their growth rate ― embryo to embryo communication.
"Turtle embryos are somehow communicating their developmental rates to each other so that they can emerge as a group," said Ricky-John Spencer, zoologist from the University of Western Sydney, and co-author of the study published in Proceedings of the Royal Society today.
Importance of temperature for the embryo.
River Murray Turtles lay large numbers of eggs (up to 30 in one clutch). Eggs near the top of the nest are exposed to warmer temperatures and develop faster than those in the bottom layers. Surprisingly though, all the eggs still hatch at a similar time.
Researchers found that River Murray Turtle eggs in the cooler patches of the nest can adjust their metabolic rates and increase their development, allowing them to catch up to their more advanced siblings.
In the nest there is some type of signalling between the unborn siblings that enables all eggs to develop fully and hatch together, regardless of the temperature differences. Scientists suspect that carbon dioxide levels or heart rates may be cues for increased metabolism, but further studies are needed to investigate these factors.