Exposure to Bright Light Has Little Effect on Eye Sensitivity and Ultrastructure of Saduria entomon(Crustacea; Isopoda; Valvifera)(Physiology)

概要

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Specimens of the isopod Saduria entomon were caught during late winter nights in Finland and divided into three groups: one was not at all exposed to any light and served as the control; a second was exposed to midday sunlight of 9.1×10^<20>qu/m^2s for 30min; the third was exposed to artificial white light of 4.2×10^<20> qu/m^2s during the day for 30 min. The visual sensitivity thresholds as well as V/log I curves of 15 exposed animals from 30 min to 456 h postexposure were recorded at random intervals and compared with values obtained from nine control animals. Only a very minor reduction of sensitivity in exposed animals was noticed. Parallel ultrastructural studies confirmed that light-induced structural derangements of visual membranes, known to occur in other species, were minimal, with an enlargement of microvilli to twice their normal diameter being the most obvious. Spectral sensitivity curves recorded from nine control animals reverased one single peak to light of 550 nm wavelength, close to maximum transmission of the water in which the animals occur. The results show that apparently not all crustaceans possess eyes that are easily damaged by bright light and-in view of the light-induced sensitivity loss reported in Mysis relicta (13)-highlight the danger of attempting to predict how photoreceptors of another species would respond, even if the species occurred in the same habitat.
社団法人日本動物学会の論文
1991-08-15