Fluid dynamics of odor capture by olfactory antennae

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The first step in processing olfactory information, before neural filtering, is physical capture of odor molecules from the surrounding fluid. Many animals capture odors from turbulent currents or wind using antennae bearing chemosensory hairs. Much of our recent research has focused on the fluid dynamics of molecule capture by arthropod olfactory organs bearing such hairs. High-speed kinematic analyses and morphometrics of the olfactory antennules of lobsters, crabs, and stomatopods, coupled with experiments using dynamically-scaled physical models, showed that these crustaceans flick their antennules at the critical velocity at which their arrays of chemosensory hairs become leaky (i.e. at which water can flow between the hairs in the array), thus these animals take discrete water samples in space and time (i.e. they "sniff"). We found that antennule flicking has a profound effect on the flux of molecules to the chemosensory hairs, and we have been measuring how flicking antennules physically filter the information (i.e. the spatial and temporal distributions of concentration) in turbulent odor plumes in the environment.

We have also studied pheromone molecule capture by the feathery antennae of moths. We used high-speed kinematic analysis of wing beating and anemometer measurements of the air flow this produces past antennae, coupled with mathematical modeling of pheromone diffusion in the air flow between sensory hairs on the antennae. We found that wing fanning increases pheromone interception rates by two orders of magnitude because the antennae undergo a transition in their leakiness to air flow at the air velocities the wings produce.

Selected references on this topic

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