Whale sharks are "filter feeders": as they swim through the water, they hold their mouths open to strain out plankton, crustaceans, and small schooling fish such as sardines or mackerel. They are also able to actively suck water into their mouths to feed.
由於大嘴裡缺乏尖牙利齒，在游泳行進中，鯨鯊以張大嘴「濾食」方式，將食物迎入口中，牠們也會主動「吸食」浮游生物、甲殼動物，和沙丁魚、鯖魚等小型群聚性魚類。