The Gills push the oxygen-inadequate water out by means of openings in the perimeters of the pharynx. Cartilaginous fish have various gill openings: sharks typically have 5, at times six or 7 pairs; they typically must swim to oxygenate their gills. Bony fish have only one gill opening on either https://maps.app.goo.gl/9y4LfCmrsyYSbzTo6