Flexi Says: Some sharks, such as whales or white sharks, need to swim to get the necessary oxygen for survival. They are dependent on the obligate ram ventilation in which they get oxygen by swimming with their mouth open. However, other sharks, such as a tiger or nurse sharks, can get oxygen through buccal pumping, using cheek muscles to draw water into the mouth and gills. Therefore, such sharks do not have to swim for their survival.
