LIFE SCIENCE

Detailed explanation-1: -These fish swim through the water with their mouth open, using their forward motion to drive water over the gills. Tunas are obligate ram ventilators, meaning they have lost the ability to simply pump sufficient water over their gills to meet oxygen demand.

Detailed explanation-2: -Ram ventilation constitutes swimming in relatively straight lines at a high rate of speed with the mouth open. This forces water through the mouth and over the gills, meaning the fish can breathe passively while swimming. Some classic examples are tuna, swordfish and shark.

Detailed explanation-3: -"Obligate ram ventilators” are sharks that have lost the ability, and the necessary anatomy, for buccal pumping, and instead can only respire using ram ventilation. Sharks from this group (which includes great white, mako and whale sharks) would indeed die from lack of oxygen if they stopped swimming.