“Sharks must keep swimming to breathe.”

It's a widely held belief that all sharks must perpetually move through the water (Review) to breathe, a notion often fueled by dramatic portrayals of powerful predators ceaselessly patrolling the ocean. This captivating image, largely associated with fast-swimming open-ocean species, has led many to assume that immobility means suffocation for any shark. However, the truth about shark respiration is far more diverse and fascinating than this singular idea suggests.

The scientific reality reveals that shark breathing mechanisms are not one-size-fits-all. While it is true for some species, known as obligate ram ventilators, that they must constantly swim forward to force oxygen-rich water over their gills, this applies primarily to active hunters like great white sharks and mako sharks. Many other shark species employ a different, equally effective method called buccal pumping. These sharks actively draw water into their mouths and pump it over their gills using specialized muscles, allowing them to remain perfectly still, often resting on the seabed or tucked into reefs, without any risk of suffocating.

This common misconception likely persists because the most iconic and frequently observed sharks, particularly in media, are often the large, continuously moving predators. The less dramatic, bottom-dwelling species that utilize buccal pumping are simply not as prominent in the public imagination. Understanding the different ways sharks breathe highlights the incredible evolutionary adaptations within this ancient group of fish, demonstrating that not all sharks are bound by the same physiological rules.