Bees are trichromats like humans. But instead of red, green, and blue, their three types of photoreceptors are sensitive to yellow, blue, and ultraviolet light. The ability to see ultraviolet light lets bees spot patterns on flower petals that guide them to nectar. In fact, Nilsson says, bees perceive so much of the ultraviolet range that “they could potentially see more than one color of ultraviolet.”
Unlike human eyes, which have only one lens, bees have compound eyes composed of thousands of lenses that form a soccer-ball-like surface; each lens produces one “pixel” in bees’ vision. That vision mechanism comes at a price—bees’ eyes have extremely low resolution, so their vision is very blurred. Nilsson calls this design “the most stupid way of using the space available for an eye.” If humans had compound eyes that performed as well as our real ones, he says, they’d each have to be as wide as a hula hoop.
This image doesn’t show the fuzziness of a bee’s eyesight—if it did, there wouldn’t be much for us to look at. But the photograph does capture the ultraviolet vision that we lack.