Gills

Learning objectives

To distinguish between pulmonary respiration and respiration with gills.
To understand the identical role played by gills and lungs in the circulation of the blood.

Aquatic animals have developed a respiratory system that is not based on the use of lungs. The organ that plays the lungs’ role and which draws oxygen from the water is the gill. This animation illustrates where the gills are located and how oxygen from the water passes into the fish’s bloodstream.