This hypnotic clip, taken by JerseyBug, is a glimpse into one of the most fascinating set of eyes among all animals, those of jumping spiders:

The spider’s anterior median eyes (the big ones) focus sharply and can even detect depth, but their abilities are limited by an extremely narrow field of vision. Spiders counteract the narrowness by moving some of the internal elements, allowing the animal to scan more broadly. Thus, the odd color changes in this jumper’s eyes are essentially the spider having a look about.