ABSTRACT
Sensory systems allow fishes to perceive and interpret their complex sensory environments and mediate key behaviors that are critical for their survival and fitness. With more than 30,000 species, fishes represent more than half of all vertebrates. They occupy a remarkably diverse range of marine, estuarine, and freshwater habitats, so it is not surprising that their sensory systems are structurally and functionally diverse, having evolved in response to a wide range of selective pressures. The sensory organs of fishes are categorized as chemoreceptors (olfactory and gustatory systems), photoreceptors (visual system), and mechanoreceptors (auditory and mechanosensory lateral line systems), which are found in all species, and electroreceptors, which are found only in a small subset of taxa. This chapter describes the structure of the sensory organs of the major sensory systems using a range of methods for visualization of cells and tissues (light and electron microscopy, µCT, etc.) and details notable aspects of variation in sensory organ structure among fish species.
