GENERAL KNOWLEDGE

Detailed explanation-1: -The gills are protected by a gill cover in teleosts and many other fishes but by flaps of skin in sharks, rays, and some of the older fossil fish groups. The blood capillaries in the gill filaments are close to the gill surface to take up oxygen from the water and to give up excess carbon dioxide to the water.

Detailed explanation-2: -Gills contain many filaments, each with thousands of tiny folds called lamellae, which greatly increase the surface area that comes into contact with water. Dissolved oxygen in seawater passes through thin membranes in the lamellae and enters the fish’s blood, and carbon dioxide is eliminated.

Detailed explanation-3: -Fishes have gills as the respiratory organs which extract oxygen dissolved in water and take away carbon dioxide from the body.

Detailed explanation-4: -Gills in fish The exchange surfaces in fish are gills . Exchange of gases in fish is very efficient because of: the large surface area of the gills. the large surface area of the blood capillaries in each gill filament.