Sherwood: Chapter 11

Objective:  During almost the entire respiratory cycle of fish, the pressure in the oral cavity remains higher than the opercular cavities, providing for a virtually continuous flow of water over the gills.

1.  Gills
        a. aquatic breathing
        b.  ventillation
2.  Gas exchange and water flow
3.  Countercurrent flow
        a.  gill arches
        b.  gill fillaments
4.  Water pumping
5.  Ram ventillation