1) The influence of several classes of factors on the agonistic behavior of the spider Microphrys bicornutus were analyzed by character analysis. 2) Static factors (sex, size, color phase, hunger state) were found to have much less influence on the behavior patterns shown in a fight than the behaviors executed by the other animal. 3) The amount of communication between crabs during a fight ranged from 1.00 bits (act 2 to 3) up to 1.57 bits (act 4 to 5). The uncertainty about a given act was reduced by knowledge of the previous act (by the other animal) anywhere from 31% (act 2 to 3) up to 81% (next-to-last-to-last act).