Turtle Eggs Communicate With Each Other to Coordinate Hatching

It's often said that timing is everything, but for Australia's Murray short-necked turtles, hatching together is a matter of life or death. The turtle eggs coordinate their hatching so they find safety in numbers at their most vulnerable age.
But how do the eggs coordinate their hatchings? Turns out, unhatched eggs can communicate with one another:

Although all the eggs were laid at the same time, in the same nest, they experience radically different environments. Those at the top of the nest, buried in warmer sun-soaked soil, can be up to six degrees Celsius warmer than those at the bottom. That’s a problem because the embryos develop at different rates depending on how hot they are. Given the gradient of warmth in the nest, the topmost turtles should hatch well before their siblings at the bottom.
That’s not what happens. Ricky-John Spencer from the University of Western Sydney has found that the Murray River turtles can tell whether their clutch-mates are more or less advanced, and shift the pace of their own development accordingly. If their peers are racing ahead, they can play catch-up.

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