In tortoises, the usually thicker and more rounded shell prioritizes defense over what structural characteristic?

Answer

Hydrodynamic efficiency

The tortoise shell's shape prioritizes defense, allowing them to retract completely, over the hydrodynamic efficiency needed for sustained aquatic life.

In tortoises, the usually thicker and more rounded shell prioritizes defense over what structural characteristic?
animalclassificationreptiletortoisetestudine