Results:Previously, researchers thought of developing embryos as cut off from the outside world. But back in 2011, researchers found that Chinese soft-shelled turtle embryos could move between warmer or cooler patches in their eggs, though they lacked any feet at such an early stage of development. Some of the same Chinese and Australian researchers who published that original finding decided to investigate further to see just how deliberate these movements are.
The turtles within the eggs held at constant temperature or those that were in the “warm on the top/cool on the bottom” group tended not to shift around in their eggs, the researchers found. Those belonging to the groups that experienced warm temperatures only on one end of their egg, however, did move around. They gravitated towards warm conditions (84-86°F), but if things heated up too extremely (91°F), they edged towards the cooler side of their egg. Crucially, the embryos that the researchers euthanized stopped moving after receiving the dose of poison. This shows that the embryos themselves, not some passive physical process, are doing the shifting.
The turtle embryos, the researchers note, behave much like adult reptiles do when thermoregulating their bodies. They warm up and cool down by moving toward or away from heat sources. For species like turtles, temperature during development plays an important part of determining the embryo’s sex. Turtle nests, which are buried in the sand, often experience a range of different temperatures, so embryos could be playing a role in determining their own gender, edging towards the cooler side of the egg if they feel like becoming a male, or the warmer side if they’re more female-inclined, the authors write.
Learn more (from Smithsonian Magazine) here.
