KOZLOWSKI, C.P.; MOORE, P. A.: The effect of odor pulse frequency on the orientation behavior of the crayfish, Orconectes rusticus.

Crustaceans use chemical signals for many purposes, including communication, and locating food, mates, and shelter. Several theories attempt to explain how organisms locate an odor source, including odor-gated rheotaxis and eddy chemotaxis, but the mechanisms by which crustaceans locate odor sources in turbulent environments are not fully understood. Chemical signals are shaped by the fluid medium in which they are found, and it is these fluid conditions that determine the signal’s spatial and temporal distribution. Under laminar flow conditions, a plume forms with distinct boundaries and gradients. However, laminar flow is rare in nature, and turbulence and plume meandering give rise to intermittency in the chemical signal. To use chemical signals effectively, organisms must employ orientation strategies that allow them to overcome signal intermittency. In this study, we presented crayfish, Orconectes rusticus to odor plumes with a controlled increase in intermittency. Crayfish were exposed to odor plumes formed by a continuously releasing jet, or to odor pulsed at 0.5, 1, 2, and 3 Hz in a re-circulating flume. Trials were videotaped from above and digitized at one frame per second for analysis. Heading angles, turning angles, path length, and the percentage of animals that successfully located the odor source were analyzed using MANOVAs. Results indicated that the orientation behavior of crayfish to pulsed odor plumes was significantly different from orientation behavior to a plume formed by a continuously releasing jet.