Tropical America is the home of the four eyed fish.

It swims on the surface of water in search of its insect food.

An eye projects above the level of the top of the head of the fish on each side.

Each eye is divided into two halves by a horizontal bar that coincides with the water level.

The upper half of the eye is suitable for vision in the air and the lower half for vision in water.

The lens of the eye is shaped so that it can focus both the air and the water images

simultaneously on two distinct retinal areas.

So the fish can see four images simultaneously –

enabling it to catch the prey in air as well as under water.