Examination of the Agonistic Behaviour of the Crayfish Orconectes Virilis By Character Analysis

The agonistic behavior of the crayfish Orconectes virilis was observed in the laboratory, with attention to the effects of size, past experience, and displays. Character analysis was utilized to quantify the relative importance of these three factors. I) In short fights, larger animals and animals which had won previous fights had a decided advantage. 2) In long fights, size and past experience seemed to have little influence on who would win. 3) Initiating an interaction gave an animal and advantage in short fights or when both were the same size. 4) Model presentations indicated that postures assumed during fights were effective visual stimuli and that the white areas on appendages are important components of displays. 5) The greatest reduction in uncertainty concerning which behavior pattern would occur at any time in a fight came from knowing the just previous act of the other crayfish. 6) The amount of information transmitted from one crayfish to another by displays increased during fights to a peak of 160 bits (53% uncertainty reduction) in the middle of fights. 7) Partitioning the data into long or short fights and into initiator-won or defender-won fights increased the apparent importance of inter-animal communication.