Photoperiodizität als Ursache des von der Mondphase abhängigen Metamorphose-Rhythmus bei dem Polychaeten Platynereis Dumerilii

Abstract

The sexual form of Platynereis dumerlii matures and swarms either in free nature or in year-long breeding in the laboratory in a rhythm dependent on change of moon-phase. This lunar periodicity of metamorphosis and swarming can be suppressed completely by lighting the cultures continuously. On the other hand, an artificial rhythm can be induced entirely artificial by rhythmic alternation of half-day and whole-day illumination periods in which even very low light intensities (0.02 up to 0.26 Lux) are effective. This experimentally induced swarming rhythm is independent of the lunar rhythm which occurs under the natural lighting conditions of the controls and can be changed by corresponding changes of the artificial lighting rhythm. It is shown thereby that the lunar periodicity of P. dumerlii is caused by moonlight.