Page 110 - Engineering in Nature

Engineering in Nature

beneath the surface its pupils remain above the surface of the water
and constantly scan the air. In this way the fish is able to feed on fly-
ing creatures or flee swimming ones.
The two separate focal points in the fish's eye let it receive two im-

ages at the same time.
A spotted band of tissue containing pigment and each of the visi-
ble irises divide each eye into two halves at the water line, and these
form two pupils, one above the water and the other beneath it.
Looked at from above, the irises resemble fingers floating in the air in-
side protuberant eyes. 34
The four-eyed fish is able to leap into the air to catch insects and to
dive into the water to hunt swimming creatures. However, it mainly
catches crustaceans moving in the shallow water near the shore,
algae, or insects trapped on the water's surface.
Scientists have established that the fish pays more attention to the
air, where it can perceive objects that are smaller and more distant.
Even so, it frequently dives down into the water to feed or to escape
predators.

• How Did This System Come Into Being?
It's no doubt that it is impossible for a fish to design two different
visual optical systems for itself, according to the different optical
properties of air and water, and then to install both systems so that
they can work in harmony within a single eye.
Could its eyes have come into being by random processes, as the
theory of evolution maintains? In other words, could this optical de-
sign—the likes of which is found nowhere else—have appeared by
chance mutation in one individual's eyes, and then have been trans-

mitted to subsequent generations?

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