MICROANATOMY

Detailed explanation-1: -Respiration in fish takes place with the help of gills. Most fish possess gills on either side of their head. Gills are tissues made up of feathery structures called gill filaments providing a large surface area for exchange of gases.

Detailed explanation-2: -The primary site, the gills, is designed for gas exchange between blood and water. There are many accessory respiratory surfaces, which in general are associated with the movement of fish from a hypoxic aquatic to an aerial environment and are designed for gas exchange between blood and air.

Detailed explanation-3: -The arches give the structure of the gills and are where the filaments are attached. The filaments are covered with small blood vessels called capillaries. This is where the gas exchange between oxygen and carbon dioxide occurs.

Detailed explanation-4: -Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. Within the gill filaments, capillary blood flows in the opposite direction to the water, causing counter-current exchange. The gills push the oxygen-poor water out through openings in the sides of the pharynx.