Color vision without perceiving colors

The animals that can see colors do so thanks to the photoreceptors — a group of specialized cells at the back of the retina. Scientists know three types of photoreceptors: rods, cones, and intrinsically photosensitive retinal ganglion cells.

However, animals like octopuses, calamari, and other cephalopods have only a single photoreceptor channel. Still, they use color to camouflage themselves and escape from predators or change their color to hunt and communicate with other animals.

The mystery of how these animals can see the color without photoreceptors has puzzled marine biologists for a long time.

Now, scientists Alexander L. Stubbs and Christopher W. Stubbs presented a viable solution to this problem. There might be a chance that animals like Sepia Bandesis that you can see in the picture above use the chromatic aberration (an optical distortion when a lens fails to focus all colors at the same point) produced by its particular pupil shape to perceive colors.

The scientists studied the pupils of these animals and discovered that their pupils maximize the spectral information at the expense of image acuity. This discovery shows that there might be more than one evolutionary path to get a color vision.

Credit Roy L. Caldwell