Fish hide from predators with body colors that dapple like light across a rippling pond.
Until the last few years, they were also at least partially unanswerable—because color researchers are only human, which means they can’t see the rich, vivid colors that other animals do.
And the first eye-like structures—flat patches of photosensitive cells—probably didn't resolve much more than that.
“The problem with using just light and dark is that the information is quite noisy, and one problem that comes up is determining where one object stops and another one starts.
And context on a scene is an evolutionary advantage.
Every time they get hit with a photon—a quantum piece of light itself—they transduce that signal into an electrical zap to the rudimentary animal's rudimentary brain.