LUNAR ORIENTATION OF ORCHESTOIDEA CORNICULATA STOUT (AMPHIPODA)

Abstract

An analysis of the moonlight orientation of Orchestoidea corniculata demonstrated: (1) that lunar azimuth is the primary orientation stimulus under the experimental conditions; (2) that multiple photo-bulb flashes bias the resulting orientation; and (3) that this species, after 10 hours or more in total dark, initially orients to the mooh with a relatively constant angle, regardless of lunar stage or position. This last result is not compatible with the hypothesis that the species possesses a continuously-operating lunar physiological rhythm similar to that claimed for Talitrus saltator. Exposure of the animals to more natural lighting conditions, however, produced some evidence for time-shifted angles of lunar orientation.