Respiratory System
Shark Diagram
Sharks breathe by pumping water over their gills, which they do by opening and closing their mouths. Water enters through the gill chambers and exits through the gill slits. Blood in the gill filaments absorbs oxygen from the incoming water. Gill rakers are cartilaginous projections on the gill support structure, they protect the delicate gill filaments from particles in the water that might damage them.
Shark Cartoon
Most sharks have low blood pressure and because of this must swim continuously to circulate the blood. The respiratory system of a shark is very different from a humans because sharks do not have a trachea, lungs, and a diaphragm for gas exchange.