rudoff@MDI.COM (Doug Rudoff) (03/26/91)
Am I right in remembering that bird color vision works diffrently than in mammals? I believe that the color sensitive cells of birds have a colored dye (red, green or blue) to filter out other wavelengths of light and the cell just detects the intensity of the filtered light instead of being sensitive around a certain wavelength. What other methods of color vision do animals have" -- -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Doug RUDOFF Motorola Mobile Data Bothell, WA uunet!mdisea!rudoff (206) 487-5937 rudoff@mdi.com -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
rowe@pender.ee.upenn.edu (Mickey Rowe) (03/27/91)
In article <1991Mar25.233022.5182@MDI.COM> rudoff@MDI.COM (Doug Rudoff) writes: > >Am I right in remembering that bird color vision works diffrently than >in mammals? You're partly right. >I believe that the color sensitive cells of birds have a >colored dye (red, green or blue) to filter out other wavelengths of >light and the cell just detects the intensity of the filtered light >instead of being sensitive around a certain wavelength. Many avians and reptiles have "oil droplets" at the entrances of their cones. These droplets have various absorption spectra within a given animal, and hence have different "colors". It is suspected that they modify the overall spectral sensitivity of the photoreceptors and hence could produce cells that are functionally differentiated even though they express the same pigment. (In at least some of these animals, more than one type of pigment is expressed as well. I think that some turtles potentially have hexachromatic vision due to different matches between expressed pigment and associated oil droplet!) Last I heard (although there's no reason to suspect that this scenario is wrong) no one has demonstrated that the oil droplets actually function as such. I can think of a couple of ways of testing the idea... I just don't think that anyone has gotten around to it. Does anyone know if I'm wrong? >What other methods of color vision do animals have" I don't know if you'd call this a different mechanism, but the pigments in the octopus have a strange sort of within photoreceptor opponency... the chromophore can be converted from the 11-cis to the all trans form or vice versa by the reception of a photon. Short wavelength photons tend to drive the reaction one way while long wavelength photons tend to drive it the other. The signal from the photoreceptor thus represents a subtraction of the signals from different parts of the spectrum. >-- >-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= >Doug RUDOFF Motorola Mobile Data Bothell, WA uunet!mdisea!rudoff >(206) 487-5937 rudoff@mdi.com >-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Mickey Rowe (rowe@pender.ee.upenn.edu)