INDUCTION OF MOLTING IN THE CRAYFISH, CAMBARUS, BY MODIFICATION OF DAILY PHOTOPERIOD

Abstract

Three groups of young Cambarus virilis were maintained at equivalent temperatures but under different conditions of lighting. Records were kept of the number of molts, number of deaths, and date of occurrence. Also, gastroliths of moribund animals were weighed to provide an additional index of position in the molt cycle. Daily exposure to "normal" day-length (approximately 10 hours) or to 20 hours of light per day was effective in inducing molt when compared with a control group in constant darkness. Furthermore, the group receiving 20 hours of light per day responded significantly more than the group receiving "normal" daylength exposures. All differences are statistically significant. Implications of these results are discussed.