How do fish breathe under water?


Fish breathe under water using the oxygen that is dissolved in water. To absorb oxygen from water, fish use special type of organs called gills. Gills are full of blood vessels. Also, the walls of the gills and blood vessels are very thin. Now, during breathing, fish take in water through their mouth and forcefully push it through their gills. When the water moves through the gills, the dissolved oxygen from the water passes through the thin walls of gills and blood vessels and enters the blood. Apart from this, the waste carbon-di-oxide in the blood passes into the water. Thus,helping fish to breathe under the water.

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