They have a system of external openings called spiracles, that lead to a branching network of tubes called tracheae, that diffuse oxygen through their bodies.
It is certain that the mouth indirectly communicates with the spouting canal; but it cannot be proved that this is for the purpose of discharging water through the spiracle.
On every side the seven gables pointed sharply towards the sky, and presented the aspect of a whole sisterhood of edifices, breathing through the spiracles of one great chimney.
Nurse sharks even nap on the seafloor; however, they use a form of ram ventilation in which they draw in water through nostril-like structures near the eyes, called spiracles, and force it out through the gills.
You would almost think a great gun had been discharged; and if you noticed the light wreath of vapor from the spiracle at his other extremity, you would think that that was the smoke from the touch-hole.