University of Western Sydney researcher Ricky-John Spencer randomly collected turtle eggs then put them into two groups. One group was incubated at 25 degree Centigrade, the other group are 30 degrees. They were then all brought together and kept at the same temperature: they all hatched at the same time.
Jessica McGlashan took a closer look. She brought a female turtle into the lab and collected the eggs the turtle laid. One half of the eggs were put into the incubator at 30 degrees, While the other half received 26 degree incubation. Some eggs from both temperatures were then put into one group in the incubator at the higher temperature and those who had been initially incubated at 26 degrees were tested. They did indeed develop faster.
A group of eggs was kept at 26 degrees throughout. As the days went by the faster developing embryos who were now at 30 degrees exhaled more carbon dioxide and their heart rates were faster than the embryos kept at 26 degrees.
Baby turtle don't actually communicate verbally, but they can "hear" each others heart beat, or rather feel the vibration of heart beats because the eggs are touching. They could even be measuring the carbon dioxide level.