THE INTRARHABDOMAL FILTERS IN THE RETINAS OF MANTIS SHRIMPS

The intrarhabdomal filters in the photoreceptors of compound eyes of 32 species of mantis shrimps (Crustacea: Stomatopoda), representing seven families within the superfamilies Lysiosquilloidea and Gonodactyloidea, were surveyed by microspectrophotometry of filters in fresh cryosections of the retina. A total of up to four classes of filters exist in stomatopods: two each in Rows 2 and 3 of the midband. All lysiosquilloid species lacked the proximal filter in Row 3; a few also lacked the proximal Row 2 class. While most gonodactyloid species had all four possible classes, in some species the proximal filters of Row 3 and (in one case) Row 2 were missing. In all, at least 11 distinct spectral classes of pigments were found. Absorption spectra suggested that the filter pigments were probably carotenoids or carotenoproteins, although the distal filter of Row 3 was often exceptional, appearing to contain a mixture of pigments. While the types of pigments found in the filters of the various species generally followed taxonomic lines, numerous exceptions were found that were apparently related to the ecological requirements of the various species.