WHY Fishes don’t Blink?

• Fishes don’t blink because fishes don’t have eyelids to blink. This is the reason they sleep with their eyes open.
• Fishes are always in the water. Therefore there is no need to keep the eyes moist. They are soaking their eyes in water all the time. So the risk of exposing their cornea is not a risk factor for them.
• The only exception is the shark. SHARK is the only fish that Blinks.
• Shark has nictitating membrane that works like an eyelid which makes it to blink.
• Nictitating membrane is a whitish or translucent membrane that forms an inner eyelid in sharks, reptiles and birds.