RED AND GREEN COLOR FORMS IN THE COMMON SHORE CRAB CARCINUS-MAENAS (L.) (CRUSTACEA, BRACHYURA, PORTUNIDAE) - THEORETICAL PREDICTIONS AND EMPIRICAL-DATA

The shore crab Carcinus maenas (L.) is known to exhibit a range of car apace colours from green through orange to red. Recent studies have de monstrated that the different colours reflect increasing lengths of in termoult duration, with clear physiological and ecological differences between red and green crabs. It was hypothesized that these different colour forms represent different 'life-strategies'. However, to date, there has been no study on population dynamics which attempts to acco unt for these differences in colour. In order to test the red/green hy pothesis, theoretical predictions were made about the occurrence of re d males within a population, and the occurrence of different male colo ur forms was investigated in a population of shore crabs in the German Wadden Sea. The general differences in size and the coverage of epibi onts and the seasonal changes in abundance between red and green males were investigated. These empirical data were compared with the theore tical predictions about red males which supported the hypothesis that red and green forms represent separate phases with different 'life-str ategies' in the life cycle of Carcinus maenas.