Question

why does the inner ear of mammals use fluid pressure waves?

Answer 1

The water easily transfers vibrations to the body tissues. So, fishes have not developed sophisticated hearing system. The earlier amphibians like salamenders picked up vibrations from both water and ground. Reptiles such as snakes picks up the sound waves from the vibrations of the ground. Therefore, during the course of evolution when animals migrated from water to land, they developed the capacity to collect and amplify the vibrations in response to the environmental challenge. In mammals, the inner ear contains fluids: perilymph and endolymph which trasmits vibrations received from midddle ear ossicles to the brain through vestibulo-cochlear nerve. Thus the inner ear of mammals use fluid pressure waves.