Mantis shrimp eyes
ryanblakeley.net
ryanblakeley.net
wait what? they can bend light? make it not travel in a straight line? color me skeptical
Rather it means that the oscillations in the electrical (or equivalently, magnetic) field that the light consists of rotate around the axis that is the light's direction of travel, rather than staying in one fixed plane. The direction of travel stays constant though.
You might want to see the Wikipedia articles: https://en.wikipedia.org/wiki/Circular_polarization https://en.wikipedia.org/wiki/Elliptical_polarization
One way to think about this is to pick x and y directions perpendicular to the light's path of travel, and break down the light's oscillations into x and y components. Linear polarization occurs when these components are in phase with each other, and elliptical polarization occurs when they're not. When they're perfectly one quarter turn out of phase, you get circular polarization.
Also of interest, mantis shrimp are edible and quite delicious.
The Oatmeal claims that, "the mantis shrimp sees a thermonuclear bomb of light and beauty." This piece contradicts that claim:
"Mantis shrimp have twelve photoreceptor classes. Humans have three. We derive a spectrum of colors through comparisons between our three classes; this is called the opponent process or opponency. Mantis shrimp do not do this. They collapse the spectrum into just twelve colors."
It's more like a 12 color lookup table.
> Every kind of red stimulates the bottom receptor of row 3. All shades of violet stimulate the top receptor on row 1
That's based on an experiment where they were trained to attack colored lights for a reward.
The comic also says they have 16 color receptors, but the other 4 (2 in the midband and 2 in the hemispheres), as far as anyone knows, aren't involved in color vision.
If so, I think that's still kind of a cool thing to think about.
It's an interesting question. If you want to read more, the two researchers quoted in the book that I was summarizing are Justin Marshal and Mike Land. Each has a handful of papers that are cited in the bibliography.
Instead of co-located and connected cones for different colors, they drag their eyes across a scene, so the comparison can happen across time instead, like a push broom sensor.