Sense_Organs_in_Teleosts and other fishes.pptx

Sense_Organs_in_Teleosts and other fishes.pptx

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  Sense Organs inTeleost Fishes Showkat Ahmad Wani
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  Introduction • Teleost fishes,the most diverse group of bony fishes, rely on highly specialized sense organs to detect changes in their environment. • These sensory systems help them locate food, avoid predators, communicate, and navigate through their aquatic habitats. • The primary sense organs in teleost fishes include 1. The lateral line system, 2. Eyes, 3. Olfactory organs, 4. Taste buds, 5. Auditory system, and 6. Electroreceptors.
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  1. Lateral LineSystem • The lateral line system is a unique mechanoreceptive sensory structure present in teleost fishes. It detects water movement, pressure changes, and vibrations. • Structure • Consists of a series of neuromasts (sensory hair cells) located along the body and head. • Neuromasts are either superficial (on the skin) or canal- based (embedded in subcutaneous canals). • Hair cells in neuromasts are covered by a gelatinous cupula that transmits water movements to the sensory receptors. • Function • Detects water currents, facilitating orientation and schooling behavior. • Helps in prey and predator detection. • Aids in obstacle avoidance, especially in low-light or turbid water conditions.
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  2. Vision (Eyes) •Teleost fish eyes are highly adapted for underwater vision, responding to different light levels and detecting motion. • Structure • Cornea: Transparent and relatively flat (since refraction in water is minimal). • Lens: Spherical, allowing better focus under water. • Retina: Contains rods (for dim light) and cones (for color vision). • Tapetum lucidum: Present in some species for enhanced night vision. • Iris: Adjusts the amount of light entering the eye, though movement is limited in most species. • Function • Enables color vision and depth perception. • Detects movement and shapes for feeding and avoiding predators. • Some deep-sea species have enhanced vision to detect bioluminescence.
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  3. Olfactory System(Smell) • The olfactory system in teleost fishes is highly developed, allowing them to detect chemical signals in water. • Structure • Olfactory pits: Paired structures containing sensory epithelium. • Olfactory rosettes: Folded structures inside the pits that increase the surface area for detecting odor molecules. • Nasal openings (nares): Allow water flow over the olfactory epithelium. • Function • Detects food, predators, and mates. • Helps in homing and migration (e.g., salmon use olfactory cues to return to spawning grounds). • Plays a role in social and reproductive behaviors.
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  4. Gustatory System(Taste) • Taste reception in teleosts is not confined to the mouth but is also found in external structures like barbels and fins. • Structure • Taste buds: Located in the mouth, gills, lips, and sometimes skin. • Barbels: Found in species like catfish; contain taste receptors for locating food in murky waters. • Function • Helps in food recognition and prey selection. • Some species can differentiate between toxic and edible substances.
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  5. Auditory System(Hearing and Balance) • Teleost fishes detect sound waves and maintain equilibrium using their inner ear structures. • Structure • Inner ear: Contains three semicircular canals for balance and otoliths (ear stones) for sound detection. • Weberian apparatus: Present in some species like cyprinids, connecting the swim bladder to the inner ear to enhance hearing. • Otoliths (Ear stones): Calcified structures that detect sound vibrations and gravitational changes. • Function • Allows detection of sound waves and vibrations. • Helps in orientation and balance control. • Enhances hearing ability in species with the Weberian apparatus.
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  6. Electroreception • Someteleost fishes have specialized receptors for detecting electric fields in their surroundings. • Structure • Ampullary receptors: Found in skin pits, detecting weak electric fields. • Tuberous receptors: Found in species with electric organs, helping in active electrolocation. • Function • Used for navigation and prey detection in murky or dark waters. • Helps in communication and species recognition in electric fishes (e.g., knifefish, electric catfish).
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  Conclusion • Teleost fisheshave evolved highly specialized sense organs to adapt to their aquatic environment. • These sensory systems provide critical information about food, predators, mates, and environmental conditions, allowing teleosts to thrive in diverse habitats.
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  Thank U