Lobster sniffing: antennule design and hydrodynamic filtering of information in an odor plume.

The first step in processing olfactory information, before neural filtering, is the physical capture of odor molecules from the surrounding fluid. Many animals capture odors from turbulent water currents or wind using antennae that bear chemosensory hairs. We used planar laser-induced fluorescence to reveal how lobster olfactory antennules hydrodynamically alter the spatiotemporal patterns of concentration in turbulent odor plumes. As antennules flick, water penetrates their chemosensory hair array during the fast downstroke, carrying fine-scale patterns of concentration into the receptor area. This spatial pattern, blurred by flow along the antennule during the downstroke, is retained during the slower return stroke and is not shed until the next flick.