Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms ?

Explanation

Aquatic organisms like fishes obtain oxygen from water present in dissolved state through their gills. Since the amount of dissolved oxygen is fairly low as compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms .
Terrestrial organisms use the oxygen present in the atmosphere in the atmosphere for respiration. This oxygen is absorbed by different organs in different animals.