n.
Sensory process by which organisms respond to external chemical stimuli, by employing specialized cells (chemoreceptors) that convert the stimuli directly or indirectly into nerve impulses.
Chemoreceptors that are components of sensory neurons that directly convert chemical stimuli are called primary receptors. Secondary receptors are not part of neurons but respond to stimulation by inducing activity in an adjacent neuron. Most mammals possess two classes of chemoreceptors: the primary receptors involved in smell and located in the epithelium of the nasal cavity and the secondary receptors involved in taste and located in the tongue's taste buds. Aquatic animals and terrestrial species with mucus-secreting skins typically possess chemoreceptors all over the body. For many animals, chemoreception is the most important means of receiving information about their surrounding environment. Chemoreception plays roles in finding appropriate food and in reproductive behaviour (see pheromone s). It serves additional purposes in some animals, such as distinguishing members of the same community from outsiders.