Application of an invariant spectral form to the visual pigments of crustaceans: Implications regarding the binding of the chromophore

Abstract

Visual pigment absorption spectra were measured in single photoreceptors of a stomatopod, a crayfish, a hermit crab, and five species of brachyuran crab. All fitted a Mansfield (1985) invariant form for visual pigment, the form also fitted by vertebrate retinal-based visual pigments. This is consistent with a theoretical model based on the structure of visual pigment molecules (Greenberg et al., 1975; Honig et al.,1976) which predicts that spectral bandwidth decreases as λ max increases. The conformation to the invariant form implies that for any given chromophore bandwidth times λ max is a constant.