Spectral tuning and the visual ecology of mantis shrimps

The compound eyes of mantis shrimps (stomatopod crustaceans) include an unp aralleled diversity of visual pigments and spectral receptor classes in ret inas of each species. We compared the visual pigment and spectral receptor classes of 12 species of gonodactyloid stomatopods from a variety of photo environments, from intertidal to deep water ( > 50 m), to learn how spectra l tuning in the different photoreceptor types is modified within different photic environments. Results show that receptors of the peripheral photorec eptors, those outside the midband which are responsible for standard visual tasks such as spatial vision and motion detection, reveal the well-known p attern of decreasing lambda(max) with increasing depth. Receptors of midban d rows 5 and 6, which are specialized for polarization vision, are similar in all species, having visual lambda(max)-values near 500 nm, independent o f depth. Finally the spectral receptors of midband rows 1 to 4 are tuned fo r maximum coverage of the spectrum of irradiance available in the habitat o f each species. The quality of the visual worlds experienced by each specie s we studied must vary considerably, but all appear to exploit the full cap abilities offered by their complex visual systems.