Selective ablation of antennular sensilla on the Caribbean spiny lobster Panulirus argus suggests that dual antennular chemosensory pathways mediate odorant activation of searching and localization of food.
In spiny lobsters and other decapod crustaceans, odorant-mediated searching behavior patterns are driven primarily by chemosensory neurons in the antennules. Two groups of antennular chemosensory neurons can be distinguished on the basis of the sensilla that they innervate and their central projections: those that innervate the aesthetasc sensilla on the lateral flagella and project into the glomerularly organized olfactory lobes, and those that innervate other (i.e. non-aesthetasc) sensilla on both lateral and medial flagella and project into the stratified and non-glomerularly organized lateral antennular neuropils. By ablating different groups of antennular sensory neurons or sensilla, we examined the role of aesthetasc and non-aesthetasc chemosensory neurons in regulating local searching behavior of Caribbean spiny lobsters, Panulirus argus, for food (squid) in a low-flow environment. The results show that odorant-mediated activation of searching and localization of food under these conditions requires only a subset of functional antennular chemosensory neurons, since neither aesthetasc chemosensory neurons nor non-aesthetasc chemosensory neurons are by themselves necessary for these types of behavior. However, ablation of aesthetasc chemosensory neurons together with subsets of non-aesthetasc chemosensory neurons from either the medial or lateral flagella impairs the ability of lobsters to locate the food. This reveals a large degree of functional redundancy but also some complementary functions between aesthetasc and non-aesthetasc chemosensory neurons, and hence between these dual antennular chemosensory pathways, in odorant-mediated searching behavior of lobsters under these conditions.