The Ultraviolet Vision of Bees

Again from Erwin Schrodinger’s Mind and Matter:

“…Bees, for example, have a colour vision reaching well into the ultra-violet; they are true trichromates (not dichromates, as they seemed in earlier experiments which paid no attention to the ultra-violet)….”

Now, leaving aside for a moment the subject of tri- or di- chromicity, I would propose that the ultraviolet (UV) vision of this species results from their retinal receptors being of smaller diameter than the human variety. Such a smaller diameter will in turn result in smaller receptor-to-receptor appositional length extending the short wavelength limit of the bee’s visual response to shorter wavelengths (I don’t know if bees have cones and/or rods). In a cursory look at the literature this seems to be true although it bears more looking into. Someone?

As to the tri- or di- chromicity of bee’s vision, this will depend, following from my ideas, as to whether their retinas possess two distinct sizes (i.e., diameters) of receptors. It follows from my concept that only a retina composed of receptors of two (or more) sizes can have either type of chromicity, or, in fact, any color vision at all..

An interesting thought following from what I have been discussing lately about the consequences of extending the short wavelength end of the visual band into the higher energy radiation of the UV region and pointing out the possibility of the biological damage that might ensue. What are the implications as to biological damage of the UV vision of insects? Might their retinas possess some damage-inhibiting mechanism not possessed by humans (or might they just not live long enough!)? Might there be some lesson here relative to the prevention of the macular degeneration condition in human vision?

GCH