Key 1.  Parabranchial Chambers 2.  Gill Arches 3.  Spiracle 4.  Internal Gill Slits (5)

    Water can enter the shark through the mouth or spiracle. The spiracle is a modified internal gill slit and is located in the top right portion of the pharynx. Following the spiracle is a row of five internal gill slits. Each gill slit leads into a gill chamber. The parabranchial chamber lies between the body wall and the gills in the gill chamber. The gill arches connect directly with the tissue of the pharynx, and contain gill rakers, which prevent food particles from getting into the gill chamber.