Stomatopods rule! They have 16 photoreceptor classes! Humans? A paltry 3! (Psssht, okay — and mayyybe up to 4. Rarely.) PLUS stomatopods can distinguish between linearly and circularly polarized light!
Slide by Michael Bok: http://arthropoda.southernfriedscience.com/?p=1776
“This is a comparison of photoreceptor classes in human and mantis shrimp retinas. Each photoreceptor class has a distinct wavelength sensitivity curve. On the human plot, you can see our three cone photoreceptor classes; blue, green, and red. These receptors cover the electromagnetic light spectrum between 400 nm (violet) and 700 nm (red). Our brains are able to process relative stimulation between the three cone photoreceptor classes, allowing us to differentiate many colors.
Mantis Shrimp don’t have the advantage of a large brain for downstream processing, so they take another approach to seeing many colors: They have 16 distinct photoreceptor classes, packed via optical filtering into tight slivers of the spectrum. Of these, five classes are sensitive to UV light, below our visual range (these are the receptor classes that I am attempting to characterize). In addition, not shown in this slide, mantis shrimp can discriminate linearly and circularly polarized light.”
Comic from Abstruse Goose: http://abstrusegoose.com/421
(Excellent reference in filename: if_the_doors_of_perception_were_expanded_everything_would_appear_as%20it_is-infinite.jpg)