With a flat shell, the Argentine snake-necked turtle (Hydromedusa tectifera) often rights itself by pressing its head against the ground with its muscular neck, levering itself onto its belly. Credit: Gaabor Domokos.
For turtles, lying belly-up is a helpless, life-threatening situation.
Now it appears many turtles evolved shells with unique shapes to easily help them flip back onto their bellies if they find themselves on their backs.
"Before starting this project, I always thought animals such as turtles worked hard to right themselves, and what this showed was this need not be the case—they can just have a good shape for their shell that does most of the work," applied mathematician Peter Varkonyi at the Budapest University of Technology and Economics in Hungary told LiveScience