Why don’t fish blink, and if they do, how do they?

From Issue: Discovery 2/1/2012

Dear Mary Esther,

That is a great question. I like to look at colorful fish in a fish tank, and you probably do, too. If you watch them for long, you will notice that most of the fish in a fish tank do not blink their eyes. The reason for this is quite simple—they don’t have eyelids. They can’t blink because they don’t have any eyelids to blink with. When we think about that, it makes perfect sense. God designed the human eye to blink. One main reason humans blink is so that their eyes stay moist. But since fish live in water, they do not need to keep their eyes moist. They are soaking wet all the time. There are some exceptions to this. Sharks actually do have eyelids and a membrane that they can “blink” over their eyes. They don’t use this membrane, however, to moisten their eyes. Instead, they put the membrane over their eyes to protect their eyes when they are attacking their prey. There are other fish, like the mudskipper, that have a membrane that covers their eyes all the time. The way that they keep their eyes moist is to roll their eyes back into their eye sockets. Thanks for writing with your excellent question, and thanks for reading our magazine. Isn’t it wonderful to see how God designed His amazing creatures?


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