The olfactory pathway for individual recognition in the American lobsterHomarus americanus

Abstract

SUMMARY Individual recognition in the lobster Homarus americanus(Milne-Edwards), is based on detection of urine pheromones viachemoreceptors of the lateral antennular flagellum. The specific sensory pathway mediating this recognition is not known. Most of the chemoreceptor cells of this flagellum are found in the unimodal aesthetasc sensilla and project specifically to the glomeruli of the olfactory lobe in the brain. Additional chemoreceptor cells are located among mechanoreceptor cells in bimodal sensilla, including the guard hairs; they do not project to the olfactory lobe. This neuroanatomy suggested that aesthetascs were essential to all complex chemosensory tasks until it was shown that spiny lobsters Panulirus argus can still perform complex food odor discrimination and localization tasks without aesthetascs. Here, we demonstrate that the aesthetascs of H. americanus contain the chemoreceptors necessary for individual recognition of familiar opponents. In contrast to intact and guard hair-shaved animals, lobsters with aesthetascs removed did not recognize previous opponents as shown by second encounters statistically similar in length and aggression to first-encounter fights. Non-aesthetasc chemosensory pathways were incapable of rescuing opponent recognition. Subsequent lesion of all remaining chemoreceptor cells (by immersion in distilled water) abolished recognition and renewed fighting.

Dine or dash? Turbulence inhibits blue crab navigation in attractive–aversive odor plumes by altering signal structure encoded by the olfactory pathway

“…For instance, aesthetasc chemosensors on antennules mediate attraction to conspecific urine in spiny lobsters (Horner et al, 2008b), and mediate individual recognition in clawed lobsters and crayfish (Horner et al, 2008a;Johnson and Atema, 2005), and responses to female pheromones in blue crabs (Gleeson, 1982). It appears as though these antennulary chemosensors also regulate responses to injured blue crab metabolites that suppress foraging.…”

Discrimination learning with light stimuli in restrained American lobster

“…The physiological basis of visually discriminative ability of the lobsters, however, remains to be analyzed in the future study as well as the ecological meaning of such ability. But such an ability of the animal that is highly social [57,66,84,85], has a simple nervous system with identifiable neurons, and yet shows clever behavior [66,[84][85][86] would make the lobsters a useful experimental system for the neurophysiological analysis of highly complex functions of their brain such as rule learning and concept/category formation reported in some insects that are thought to have arisen from within the crustaceans to which lobsters belong [87]. Changes in the gripping action latency during training (N = 10).…”

Spiny lobsters detect conspecific blood-borne alarm cues exclusively through olfactory sensilla

“…The other is a non-olfactory chemomechanosensory pathway; it is innervated by the nine types of 'nonaesthetasc' sensilla, which contain both chemo-and mechanoreceptor neurons that project to the lateral antennular neuropils and median antennular neuropil (Schmidt and Ache, 1996a;Schmidt and Ache, 1996b). The aesthetasc-olfactory lobe pathway may uniquely process detection of pheromones and other conspecific odors, whereas the non-aesthetasc-lateral antennular neuropil pathway and the aesthetasc pathway both detect general odors including food chemicals (Gleeson, 1980;Gleeson, 1992;Steullet et al, 2002;Schmidt and Derby, 2005;Johnson and Atema, 2005;Horner et al, 2008a;Horner et al, 2008b).…”