Meeting Abstract

45.8  Tuesday, Jan. 5  Turbulent mixing inhibits discrimination of attractive vs. aversive chemicals in crabs by eroding small scale filament structure impinging on antennulary chemosensors WEISSBURG, M.J.*; BERKENKAMP, K.; MANKIN, D.; GA Tech; GA Tech; GA Tech marc.weissburg@biology.gatech.edu

Animals distinguish chemicals in environments where cues from different sources may be mixed. Although the role of the fluid mixing has been investigated in the context of tracking, there is little work on the role of the physical environment in mediating the ability of animals to discriminate different chemicals, despite the obvious relevance of this problem. We examined whether blue crabs could discriminate an attractive from an aversive odor (food vs injured blue crab metabolites, resp) under various mixing conditions, using the ability of crabs to track to the source in a flume as the behavioral endpoint. When attractive and aversive cues are emitted from separate sources, blue crabs recognize the presence of food and locate the attractive source at a frequency indistinguishable from that occurring without the aversive substance. Discrimination of the attractant occurs despite the fact that qualitative flow visualizations indicate attractive and aversive odor streams intermingle. In contrast, increased turbulent mixing eliminates the positive response to food odor, which is similar to the behavior observed when attractive and aversive substances are released from a single source. Thus, turbulent mixing, which is associated with filament homogenization, diminishes the capacity to register the presence of the attractive substance. Significantly, animals with antennulary chemosensensors rendered non-functional (using distilled water) respond to the attractive source in dual plume experiments, even in the presence of enhanced mixing. This suggests antennulary receptors are responsible for discrimination, and that spatial discreteness of odor filaments at this scale is a necessary signal feature