Most mammals and reptiles rely on a flexible rib cage that expands to allow them to breathe, but turtles use abdominal muscles attached to the shell instead: one to breathe in, and one to breathe out.

多数哺乳动物和爬行动物都仰赖一个能扩张的弹性胸廓呼吸，而乌龟则用附在壳上的腹肌来呼吸：一组腹肌帮助吸气，另一组则帮助呼气。