Eye design and color signaling in a stomatopod crustacean Gonodactylus smithii

Many species of stomatopod crustaceans have multiple spectral classes of ph otoreceptors in their retinas. Behavioral evidence also indicates that stom atopods are capable of discriminating objects by their spectral differences alone, Most animals use only two to four different types of photoreceptors in their color vision systems, typically with broad sensitivity functions, but the stomatopods apparently include eight or more narrowband photorecep tor classes for color recognition. It is also known that stomatopods use se veral colored body regions in social interactions. To examine why stomatopo ds may be so 'concerned' with color, we measured the absorption spectra of visual pigments and intrarhabdomal filters, and the reflectance spectra fro m different parts of the bodies of several individuals of the gonodactyloid stomatopod species, Gonodactylus smithii. We then applied a model of multi ple dichromatic channels for color encoding to examine whether the finely t uned color vision was specifically co-evolved with their complex color sign als. Although the eye design of stomatopods seems suitable for detecting co lor signals of their own, the detection of color signals from other animals , such as reef fishes, can be enhanced as well. Color vision in G. smithii is therefore not exclusively adapted to detect its own color signals, but t he spectral tuning of some photoreceptors (e.g. midband Rows 2 and 3) enhan ces the contrast of certain color signals to a large enough degree to make co-evolution between color vision and these rather specific color signals l ikely. Copyright (C) 2000 S. Karger AG, Basel.