Changing structure and function of the ear and lateral line system of fishes during development

Adult fishes sense vibrations and disturbances in the water through the auditory and mechanosensory lateral line systems. The developmentally complete systems impart certain levels of sensitivity and acuity to a fish, but fish larvae hatch with rudimentary auditory and lateral line systems that confer poor sensory performance. The structures become more elaborate during ontogeny, with attendant improvement in performance. This review summarizes the ontogenetic changes in the peripheral anatomy of these sensory systems as well as the experimental work that has been undertaken to measure the changing functionality of each. In both systems, the number of end organs increases ontogenetically, roughly in proportion to somatic growth. Improvements in sensory function coincide with, and may be attributable to, these increases in end organs. Accessory structures that enhance functionality develop late in the larval period. Problems and recent advances in methodology as applied to larval fishes are discussed