Biological rhythms, as a result of the interplay between endogenous clocks and the environment, are very important properties of almost all organisms. The environment changes according to the time of day and year, creating therefore temporal information to the organisms. Such temporal information is registered by the clock, which "tells" the organism when to make use of the favorable season, when to avoid the effects of the unfavourable season. The changing of season is predictable at any given latitude. Hence, it is not surprising that a wide variety of organisms of all phyla use day length...