What is the Respiratory System?
Before you discover the different respiratory systems for each phylum, it might be a good idea to know what the respiratory system is. The respiraotry system is a biological system that allows oxygen to enter an organisms' body and releases carbon dioxide. The respiratory system is present in all living organisms in some way or another. This is the case because oxygen is needed by the cell to perform actions such as respiration. You will soon see that different organisms get their oxygen in different waysd, but they all have to use oxygen to survive.