Laboratory for Sensory Ecology, Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, USA i306 DA Bergman and PA Moore possibility of injury. Urine-borne chemical cues are thus expressed extrinsically as both a signal to communicate social status and as a tool to manipulate an opponent’s intrinsic neural state and behavior (Breithaupt and Eger, 2002; Bergman et al., 2004). This transfer of social information via chemical and mechanical signals can be significantly impinged upon by the extrinsic environment. When examining a dyadic agonistic interaction, we have demonstrated that both dominant and subordinate crayfish generate water currents that facilitate the sending and sampling of signals. However, dominant crayfish generate more of these currents and release urine more frequently during an encounter than subordinates. This result suggests that the transfer of social information occurs differently when a status role is achieved. A correlation of urine releases with water current generation and agonistic behaviors appears to be the eventual predictor for dominant-subordinate relationships. This may indicate that agonistic behaviors may be associated with chemical signaling that likely alters or possibly controls a receiver’s behavior during the course of an interaction. Other extrinsic factors can play a role in how sensory signals are received. For example, the physics of different environments can influence how sensory signals are transmitted within those environments. Consequently, this physical effect on sensory signals can influence how animals send or sample sensory signals. In fact, habitat specific physics may constrain or enhance signal transmission (ie light transmission in a shaded forest versus an open field) and may provide a mechanism for the evolution of sensory biases. The transmission of chemical signals is heavily dependent upon environmental flow regimes, thus crayfish found in lotic (flowing water) systems appear to be adapted for more effective communication within a lotic environment. This hypothesis is an extension of the ‘matched filter’theory of Wehner (1987) to the behavioral level. When crayfish collected from lotic systems had agonistic bouts under lotic conditions, dominant crayfish spent more time upstream than subordinate crayfish. In contrast, when crayfish were allowed to fight under lentic (no flow) conditions, regardless of status, crayfish were positioned randomly within the flume (Bergman and Moore, unpublished results). By chemically visualizing urine release during these agonistic bouts, it was possible to elucidate that crayfish released urine more often when upstream of an opponent when experiencing lotic conditions. Environments obviously constrain communication systems. The results of the flow versus no flow fighting conditions suggest that crayfish urine is deliberately released to increase the probability of communicating one’s status chemically. We have attempted to expose a few of the essential factors that influence agonistic interactions. Namely how different extrinsic and intrinsic factors alter crayfish agonistic behavior. Since social interactions in decapods are correlated with neurochemical alterations, we suggest that short-term exposure to social odors communicate these changes in some form, whereas long-term exposure may alter the functioning of serotonin or other biogenic amines in the receiving crayfish nervous system. Consequently, exposure to status odors appears to be more responsible for dominant–subordinate relationships than previously given credit. With most levels of organization, from ecology to neurons, readily accessible for detailed …