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Fish primarily use pheromones to facilitate social behavior, such as social and reproductive cues and predator avoidance. [2] Antipredation pheromones vary across species; some may emit chemical cues that provoke physiological changes (e.g. body depth increase), or cues that promote evasion (release of odor cues of dead conspecifics).
The changes in olfactory function can be placed into three categories: (1) anosmia, the inability to smell; (2) hyposmia, a reduced ability to smell; or (3) dysosmia, where olfactory signals are incorrectly processed. Most chemicals at lower concentrations cause a degree of hyposmia while at higher concentrations anosmia is the result.
Age is the strongest reason for olfactory decline in healthy adults, having even greater impact than does cigarette smoking. Age-related changes in smell function often go unnoticed and smell ability is rarely tested clinically unlike hearing and vision. 2% of people under 65 years of age have chronic smelling problems.
The Lady and the Unicorn, a Flemish tapestry depicting the sense of smell, 1484–1500. Musée national du Moyen Âge, Paris.. Early scientific study of the sense of smell includes the extensive doctoral dissertation of Eleanor Gamble, published in 1898, which compared olfactory to other stimulus modalities, and implied that smell had a lower intensity discrimination.
The olfactory lobes are very large in fish that hunt primarily by smell, such as hagfish, sharks, and catfish. Behind the olfactory lobes is the two-lobed telencephalon, the structural equivalent to the cerebrum in higher vertebrates. In fish the telencephalon is concerned mostly with olfaction. [59] Together these structures form the forebrain.
Many fish also have chemoreceptors that are responsible for extraordinary senses of taste and smell. Although they have ears, many fish may not hear very well. Most fish have sensitive receptors that form the lateral line system, which detects gentle currents and vibrations, and senses the motion of nearby fish and prey. [1]
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In some cultures negative smells can result in positive emotions where in the western world, negative smells are often met with negative emotions. The sense of smell has often been overlooked and understudied and many people often perceive olfactics as a lower importance sense as it pertains to communication. The importance and variation of ...