Did you know that there’s a fish with four eyes?

Take a look at your eyes in a mirror. What do you see? Humans have a white part of the eye, a coloured iris, and a dark pupil in the centre. The pupil is actually a hole in your eye that lets light in so that you can see. But in Central and South America, there’s a fish with two pupils in each eye! Four-eyed fishes don’t actually have four eyes – they have only one eye on each side of their heads. But each eye is divided in half, with a pupil on the top, and a second pupil on the bottom. But why would a fish need such a strange eye? The answer lies with the fish’s diet. Four-eyed fishes eat many of the insects that can be found at the surface of the water. But to eat them, the fish has to rise to the surface where it is exposed to predators like bigger fish from below, and birds or other fish-eating animals from above. The fish’s extraordinary eyes let it see above and below the water! It even has a different lens for each pupil, because light travels differently in air and in water, and without the correct lens, it’s hard to see clearly. That’s why everything looks blurry underwater unless you put some goggles on! Because the fish can see clearly above and below the water, it can watch for predators from all angles. If something does try to sneak up on it, it spots them easily and zips away!