The Efficient Fish
Fish are typical of the elegant designs found in the creation. Both function and form are united with the mechanical and biological needs of the fish to produce intelligent, beautiful, yet simple solutions for their needs.
Fish are designed so that water, containing oxygen, is taken in through the mouth and expelled from behind the gill flaps. At both these points the inward and outward pressures on the fish are the greatest. The result is the most efficient system possible - many fish need expend no extra energy to breathe when they swim.
Fish tend to have their eyes located at the point on their bodies where water pressure while swimming is zero. This is important since the curvature of the cornea of the eye determines the focus of the fish's vision. It could be disastrous to the fish if its vision changed as swimming speeds varied. The fish's heart is located over one of the points in its body where the outward pressure is greatest. While the heart muscle works by contraction, the outward pressure on the surrounding surface of the fish allows easy re-expansion of the heart for the next beat.
If fish had gears and pulleys instead of their much more sophisticated biological machinery, no one would deny it was carefully engineered by an outside intelligence.