Comparison between temperature-induced changes and effects caused by dark/light adaptation in the eyes of two species of Antarctic crustaceans.

The amphipod, Orchomene plebs, and the isopod, Glyptonotus antarcticus, both adapted to live in seawater of a temperature of -2 degree to 0 degree C, were kept for 7h at the unphysiologically high temperature of +10 degree C. Temperature elevation appeared to mimic light adaptation with regard to the position of the screening pigment granules within the visual cells, but not with respect to ultrastructural changes in the microvillar array of the rhabdom, i.e. the visual membranes. Cellular metabolism, membranous fatty acid composition, and ion fluxes, all known to be readily affected by an increase in temperature, are thought to be responsible for the observed effects. Pigment granules could possibly cause an elevation of intracellular temperatures due to the fact that they are dark and dissipate absorbed energy as heat.