The common white sucker (Catostomus commersoni ): a fish with ultraviolet sensitivity that lacks polarization sensitivity

Two families of fishes, the Cyprinidae and Salmonidae, exhibit ultraviolet sensitivity and polarization sensitivity (i.e., differential sensitivity to the orientation of the electric field of polarized light). Both of these families possess a square arrangement of double cones and/or their dividing partitions in the centro-temporal retina, an area where polarization sensitivity has been tested for and found. To correlate the presence of an ordered cone mosaic in the centro-temporal retina with polarization sensitivity in ultraviolet-sensitive fishes, we examined the visual system of the common white sucker (Catostomus commersoni) and compared it to those of the above-mentioned families. We found that the common white sucker possesses four cone-mediated neural mechanisms similar to those in cyprinids and salmonids, but it does not exhibit polarization sensitivity. In addition, unlike cyprinids and salmonids, the common white sucker shows a random cone mosaic in the centro-temporal retina. These results suggest that polarization sensitivity in ultraviolet-sensitive fishes requires an ordered double-cone mosaic in this area of the retina. Accepted: 19 July 1997