I spy with my little eye…

“To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree.”

Flat light sensitive patches (photoreceptors): Euglena

Cupped light sensitive spots: Planaria

Reflective mirror optics: Scallops

Pinhole with no lens: Nautilus

Simple eyes: Cicada

Eight simple eyes: Spider

Compound eyes: Holcocephala fusca

Camera eyes: Octopus 

Camera eyes: Homo sapiens.  Yes, me.

“Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real. How a nerve comes to be sensitive to light, hardly concerns us more than how life itself first originated; but I may remark that several facts make me suspect that any sensitive nerve may be rendered sensitive to light, and likewise to those coarser vibrations of the air which produce sound.”

– Charles Darwin