STRUCTURE AND OPTICS OF OMMATIDIA FROM EYES OF STOMATOPOD CRUSTACEANS FROM DIFFERENT LUMINOUS HABITATS

¹ Dipartimento di Informatica, via Valperga Caluso, 37, Università di Torino, 10125 Torino, Italy, Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, and Department of Biological Sciences, University of Southern California, Los Angeles, California 90007

Shapes and sizes of ommatidia in six genera of stomatopods from different luminous habitats are described. Cornea-cone apertures and acceptance angles have been calculated. The ommatidia belong to the apposition type with fused rhabdoms as in most Malacostraca, but the spindle-shaped cone and the transparent wedges under the cornea are acquisitions of stomatopods. The same is true for rhabdom specializations, especially the thin undulated rhabdoms in ommatidia of the six-row middle band of the Gonodactyloidea, that divides the eye in two halves. Several regions can be distinguished in stomatopod eyes by differences in shapes, sizes, and proportions of their ommatidia and by the skewing pattern along the columns of ommatidia. As more light becomes available in the habitat, apertures and acceptance angles seem to decrease mainly by increasing the lengths of the cones.