Question

Fish respire fastly than mammals.why

Answer 1

Answer:

Air has around twenty times more oxygen than water does, and water is also heavier than air, so it's harder to move into the fish's gills. Since there's less oxygen in the water and the water is harder to move around, fish need to breathe more quickly.

Answer 2

Smaller fish and humans breathe faster than larger fish and humans because smaller fish and humans also have smaller lungs and gills, which have less capacity to store and process oxygen than bigger lungs and gills do. ... Animals that are ectothermic don't need to heat their bodies using a process that involves oxygen.