A look into the gills of a great white shark

A close-up look at the gill filaments of Gianna, a 4.9m (16') female great white shark.

As water passes through the gills, oxygen is absorbed and passed to the shark's deoxygenated blood which is then circulated throughout the shark's body. Carbon dioxide is also passed out from the blood during the process.

Great white sharks largely rely on what is known as ram ventilation, in which the shark must continually be swimming forward to force water through its gills.

Some sharks and rays are capable of using buccal pumping in which they can pump water through their gills using the muscles around their mouths, so they don't not have to maintain forward motion in order to breathe.