Question

The breathing rate of an aquatic animal is more than that of of a terrestrial animal . Why ?​

Answer 1

Since the amount of oxygen dissolved in water is comparatively lower than that in air, the aquatic animals have to breath rapidly to take in sufficient oxygen. Thus, the rate of breathing in aquatic organisms is much faster than that seen in terrestrial organisms

Answer 2

It has to filter out the small amount of oxygen in the water, unlike terrestrial creatures.