Colour Vision and Camouflage

Colour vision is a complex biological process that affords animals a diverse array of information about their environment.  The fundamental molecular unit for vision is the opsin, a family of membrane-bound G-protein coupled receptors.  Visual opsins are expressed in the retina, and can be divided into five sub-families (i.e., RH1, RH2, SWS1, SWS2, and LWS) each characterized by their wavelength-sensitivities.  Opsin repertoires vary enormously among species.  Through whole genome duplication and tandem duplication, teleost fish possess a remarkable diversity of opsins.  We identified the flatfish as our model organism.  They are interesting because of their development, the light environments they occupy, and their ability for active camouflage.    Through sequencing and phylogenetic analysis we have confirmed eight visual opsins in flatfish.  Many flatfish species, including the Starry Flounder (Platichthys stellatus), are capable of remarkable visually-mediated active camouflage.  We designed a behavioural assay, using 10 Starry Flounder, to quantitatively estimate their colour vision acuity based on the camouflage response to varying chromatic checkerboard substrates, followed by quantitative-PCR to measure the relative abundance of the eight visual opsin genes.