ABSTRACT
Teleosts have various sense organs like an elaborate lateral line system, olfactory organs, taste buds, eyes, and membranous labyrinth (inner ear). The inner ear of teleosts is composed of the upper labyrinth containing three semicircular canals and three otolith organs: the utriculus, the sacculus, and the lagena. Each semicircular canal bears an enlargement at one of its ends named ampulla that house sensory structure, the cristae ampullaris. A lateral line system is a group of neuromasts located superficially on the skin or just under it in fluid-filled canals in all fishes. Canals of the lateral line system are filled with fluid, which transmits vibrations to the neuromasts through the skin pores. There are two types of neuromasts; free and canal neuromasts. The olfactory rosette of most teleosts consists of several olfactory lamellae radiating from a median raphe. Each lamella consists of two layers of epithelium separated by connective tissue core. The olfactory epithelium is composed of both sensory and nonsensory areas. The sensory epithelium composed of ciliated, microvillous olfactory receptor cells (ORCs), rodlet and crypt cells. The organization of the fish eye has the same general structure found in higher vertebrates. The retinal tunic is composed of 10 distinct layers.
Teleosts possess highly developed sensory organs. Nearly all daylight fish have a color vision at least as good as normal humans. Many fish also have chemoreceptors responsible for the acute senses of taste and smell. 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. Fish can sense sounds in a variety of ways, using the lateral line, the swim bladder, and in some species the Weberian apparatus.
