Two sniffing strategies in palinurid lobsters.

Most studies of lobster chemoreception have focused on the model systems of Panulirus argus (Palinuridae) and Homarus americanus (Nephropidae). We compare antennule morphology across lobsters and conduct the first kinematic study of antennule flicking in a palinurid species other than P. argus. High-speed video analysis shows that Palinurus elephas flicks at a rate more than an order of magnitude higher than in P. argus. However, both species flick their antennular flagella at a Reynolds number (Re) of approximately one, such that an asymmetry in the speed of the flick phases causes both species to have a leaky closing flick phase and a non-leaky opening phase. The antennular flagella of P. argus are nearly seven times longer than those of P. elephas, and, when compared across palinurid genera, Panulirus species sample far greater areas of water over greater spatial and time scales than do any other palinurid genera. Palinurid lobsters appear to have two sniffing strategies: low flick rates over a large area of water (e.g. P. argus) or high flick rates over a small area of water (e.g. P. elephas). P. argus is a highly informative model system in which to study aquatic chemoreception; however, its antennule anatomy and kinematics suggest a separate strategy, unique to Panulirus species, for sensing chemical plumes in fluid environments.