Baby turtles inside their eggs squirm around to chill out or to turn up the heat, new research finds, a skill that could potentially enable them to choose their own sex.
The study is the first evidence that embryonic turtles deliberately regulate their temperature. Such a talent is key for juvenile and adult turtles, which are ectotherms (otherwise known as "cold-blooded"). Because the turtles rely on outside sources to maintain their body temperature, they have to move from cool to hot spots to stay equilibrated.
In 2011, a study published in the journal Proceedings of the National Academy of Sciences found that embryos of the Chinese softshell turtle (Pelodiscus sinensis) moved toward sun-warmed ground while still in the egg. Scientists weren't sure, however, whether the embryos were simply moving to the warmest spot in the egg because they were trying to calibrate their temperature, or if they were simply floating passively toward warmth due to some sort of fluid dynamics in the egg. [Procreation Station: The Weirdest Pregnancies in Nature]
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