Man has always come to the aid of his fellows with a wealth of inventive ideas. Take bifocal eyeglasses, for example, that were invented by Benjamin Franklin. Both lenses of these glasses are ground to give two different amounts of correction. The upper half of the lens is made for distant vision, and the lower half for close vision. The wearer has merely to lower his eyes when he wishes to read and raise them if he wants to look at a distant object.
But long before man had thought about bifocals, nature was way ahead. In the quiet shallows of lagoons and freshwater lakes in Mexico, Central America, and northern South America lives (and has lived for centuries) an unusual fish known as Anableps anableps. It is also known as “Cuatro ojos,” meaning four eyes. This olivecolored fish has a remarkable ability to see in two different directions at once!
This strange fish is seldom more than eight inches long, and while it habitually floats on the surface, it actually feeds beneath the water. The sole purpose of this fish’s uniquely adapted eyes is to allow it to watch for predators, both above and below the water’s surface simultaneously. How this is accomplished is just another indication of Heavenly Father’s ability to help creatures adapt to their environment.
The oval-shaped eye of the Anableps has a pupil divided by a band of skin and a double retina. The upper portion of the eye above the surface of the water admits light through the short dimension of the eye. The lower part of the eye admits light through the long dimension of the eye. And because it swims close to the surface with its eyes partially projected into the air, Anableps can spot danger through any dimension above or below the water.
As is the case with most animals, moisture to lubricate the eyes is provided by eyelids and tear glands. But since Anableps has neither, every few minutes it has to duck its head under the water to wet the upper part of its eyes.
It would indeed be fortunate if a person wearing bifocals could wear them as this four-eyed fish does. They would be unlosable and unbreakable and free!