Why don’t fish have eyelids ?
Most fishes don’t have eyelids , and that’s because they really don’t need them . Eyelids help moisten eyes , so they don’t dry out . Eyelids also protect eyes from things in the air , like dirt and dust . Since fishes live in water , dry eyes are not really an issue . But some fish , like sharks , still have them . Other fish have special eyelids that are thick and transparent , or see-through . Scientists think these special eyelids are a lot like glasses because they help fishes focus on objects .