Final answer:
In fish gill irrigation, the buccal chamber draws water across the gills, and the opercular chamber expels water across the gills.
Step-by-step explanation:
In fish gill irrigation, the buccal chamber draws water across the gills, and the opercular chamber expels water across the gills. This process is crucial for the respiratory function of fish, enabling them to extract dissolved oxygen from water and release carbon dioxide. During ventilation, fish use rhythmic movements of the buccal (mouth) and opercular (gill cover) chambers to create a unidirectional flow of water over the gill filaments. The buccal pump facilitates the intake of oxygenated water, while the opercular pump helps expel deoxygenated water. This efficient mechanism ensures a continuous flow of fresh water over the gill surfaces, optimizing gas exchange and supporting the fish's respiratory needs in its aquatic environment.