Murray River Turtle Embryos Communicate to Coordinate Hatching

Behold the turtle. He makes progress only when he sticks his neck out.
~James Bryant Conant

A recent study indicates that the embryos of Murray River turtles communicate while still in their shells. The turtles can adjust their rate of development in the company of other eggs to coordinate the time they hatch. The eggs are laid at the same time, but the eggs near the top of the nest where the soil is warmer tend to develop more quickly that those in the deeper, cooler soil.

In the study embryos that were incubated with the more developed peers, sped up their development. Their heart rates sped up and they exhaled 67 percent more carbon dioxide than the control group.
After they hatched, it was found that the initially slower turtles had used up more of their yolk supplies in order to catch up, but were not fundamentally different from their less rushed siblings.



How the communication takes place is still a mystery. The study abstract is available here. 

Something else I learned: A group of turtles is called a bale.