Chemoreception in chronically anosmiated fish: A phenomenon of compensatory development of the gustatory system

Abstract

The main results of studying the phenomenon of recovery of sensitivity to food smells after a long olfactory deprivation found in fish are presented. This ability is detected in fish of different taxonomic groups (Chondrostei, Teleostei) having normally external gustatory receptors. At the behavioral level, this effect starts to manifest itself six weeks upon anosmia, and its development apparently ends during the first three to five months in a partial, rather than complete, recovery of sensitivity to food smells. A more prolonged olfactory deprivation (6–14 months) does not cause any further decrease in the threshold concentration of stimulus solutions. The response to other types of chemical signals (alarm pheromone) is not restored. The ability of fish after a prolonged olfactory deprivation to recover sensitivity to food smells is provided by compensatory processes taking place in the external gustatory system. Recovery occurs due to substances that have taste attraction for fish. Species were found in which the food search response in the norm is provided simultaneously by the olfactory and the gustatory systems. The anosmia of such fish leads only to a partial decrease in the efficiency of search behavior. The complementarity of chemosensory systems, their functional interaction, capacity for a compensatory development, and vicariation are considered sensory mechanisms providing the reliability of realization by fish of the most important behavioral patterns, of food, in particular.