Bony fish have a high oxygen demand due to their high activity and due to their scales being impermeable to gases they developed gills that are well adapted for gas exchange due to having a high surface area for diffusion, a good blood supply to maintain concentration gradients and thin walls to keep short diffusion distances.
The gills of bony fish are contained in a cavity and are covered by a protective bony flap called the operculum which is important to maintain the flow of water over the gills. Bony fish ventilate their gills by alternating the opening of the mouth and the operculum to ensure a continuous flow of water.
The gills of bony fish are contained in a cavity and are covered by a protective bony flap called the operculum which is important to maintain the flow of water over the gills. Bony fish ventilate their gills by alternating the opening of the mouth and the operculum to ensure a continuous flow of water.