Ventilation in fish

• The internal gills are protected by an operculum and therefore need to be actively ventilated.

  • The fish takes water in through its buccal cavity which then flows through the pharynx and over the gill plates, leaving via the opercular openings on each side of the fishes head
• The rows of gill filaments have many folds called lamellae. The folds are kept supported and moist by the water that is continually pumped through the mouth and over the gills

  • This also ensures fresh water with oxygen is always passing over the gills to maintain the concentration gradient as oxygen diffuses into the blood