Examine the diagrams. Identify the function of each part Sponges and jellyfish lack specialized organs for gas exchange and take in gases directly from the surrounding water. Flatworms and annelids use their outer surfaces as gas exchange surfaces. Arthropods, annelids, and fish use gills; terrestrial vertebrates utilize internal lungs. Compare the Respiratory System of theFrog to the Human Review the Frog Life Cycle http://www.youtube.com/watch?v=PadlN3IjyVU Workbook pages 187-190