The boa constrictor literally squeezes the life out of its prey. Coiling itself around its victim it tightens and tautens, ratcheting up the pressure until there is no breath left. Then, it swallows its meal whole.
The question is, how can it squeeze so hard without also crushing its own lungs in the process? And how can it digest the animal — which could be as large as it — without also cutting off its air supply?
The answer, scientists have found, is that the snake has the ability to shift the section of rib cage it uses to breathe, turning the lower half of its long lungs into a bellows that forces through the air — allowing it to keep on breathing.