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The visual acuity of a gastropod pulmonate mollusk Radix peregra (Müller, 1774) was estimated on the basis of phototaxis in the laboratory conditions. White cards with black vertical stripes of different angular width were used as visual stimuli. A value of the resolving angular distance of photoreceptors was 1-2°, and the calculated on its basis visual acuity -33-16.5 rad-1. The mollusc has a diurnal type of activity and lives at well-illuminated surface patches of ponds on aquatic caulescent plants that it feeds on. The results of behavioral investigation presented in this work and morpho-optical study of the eye carried out earlier allow to consider that R. peregra can identify caulescent plants, suitable for its inhabitation, feeding and travelling to the water surface.

Острота зрения брюхоногого легочного моллюска Radix peregra (Müller, 1774) (Basommatophora, Lymnaeidae)
Шепелева И.П.;