Shelbs.

sciencecenter:

Embryonic turtles communicate to coordinate when they hatch

Murray River turtles communicate with their siblings while they are still in their shells, buried under the soil, in order to coordinate when they hatch.

Achieving this synchronicity isn’t easy. Although the eggs are always laid at the same time in the same nest, those at the top of the nest near the sun-drenched soil develop much faster than those buried deeper in the cooler soil. However, Murray River turtles are able to tell whether their fellow hatchlings are more or less advanced and adapt their pace of development accordingly, allowing the slow-coaches to play catch-up. [..]

The team concluded that the embryos must be able to communicate with each other while they are still in their shells, but it’s not clear how. They suggest that it could be down to changes in the nest that trigger certain hormones that change the turtles’ metabolism. Embryos produce more thyroid hormone when oxygen levels fall. The fast-developing embryos could use up the oxygen levels around the next and emit more carbon dioxide. The reduction in oxygen could cause the slower developers to produce more thyroid hormone and therefore grow faster.

I’m inspired. When’s the last time you put that much effort into cooperating with your siblings?