What are the major differences in the respiratory (lung, gills) systems between the five organisms (Fish, Amphibians, Reptiles, Birds, and Mammals)?

Question

aaronq · Answer

fish don't have lungs, instead, they use one-directional flow of water from the mouth through the gills with a counter-current mechanism to abstract oxygen from water and deposit CO2 into it. 

reptiles use a bi-directional mechanism (like humans) but don't have diaphragms instead use their chest and throat to draw air into their lungs. 

Mammals use a bi-directional system, have lungs and a diaphragm.

Birds have these weird lungs, you can search on youtube about this, but this is the main idea: |dw:1371587540839:dw|