Fish trivia: Tuna need to swim non-stop, if you stop it will suffocate and die.

The tuna’s gill muscles have degenerated, and they always open their mouths, swimming constantly, and getting fresh oxygen through the gills. If the tuna stops swimming, it will suffocate due to hypoxia.

This kind of breathing method that makes the water flow directly through the gills to breathe oxygen is called impact breathing, and this is the type of tuna.

So tuna swims while sleeping, and so do sharks.