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Lecture 9 Perception Perception 1. Hearing 2. Smell 3. Vision 4. Lateral line 5. Electroreception 6. Touch and Taste Hearing Important in mating, prey detection, and predator avoidance We will focus on hearing in bony fishes Hearing teleost Otolith – “ear stone” • solid bone deposit • surrounded by sensory hair cells • gravity pulls down and excites sensory hair cells • also vibrate due to sound • dense otoliths take longer to vibrate & difference triggers excitation of auditory nerves Hearing teleost Gas Bladder • sound waves vibrate gas filled spaces • enhances sound detection • largest group of hearing specialist = Otophysans (>74% of freshwater spp.) • Weberian apparatus Hearing Mating calls identify sexes & conspecifics hamlets (Serranidae) Geomagnetic reception? • Not much known about how this is achieved • Lagenal otolith is a good candidate • small & very high iron content Smell Organs of smell contained within olfactory chambers • incurrent and excurrent nostril • cilia move water across • used to locate habitat, mates, prey, and to avoid predation Smell Hammerhead stereochemoreception Smell sensitivity depends on what the animal uses its sense of smell for Smell Schreckstoff alarm and reaction -Ostariophysi Vision Photoreceptors Rods • sensitive to low light Cones • greater resolution • several types • sensitive to variable wavelengths Fishes photoreceptors correlates with habitat Vision Teleosts • diameter of pupil is fixed • deep sea fishes have wide pupils Diretmus argenteus Anableps spp. Vision Elasmobranchs • have a muscular iris and can control the amount of light that enters Vision male panuco swordtail Xiphophorus nigrensis Species can detect UV sensitive photoreceptors UV-reflective markings on its tail that drives the ladies crazy but predators can’t see it Vision Sauron the deceiver… aka comet fish Calloplesiops altivelis • fishes use visual mimicry to deceive • e.g., ocelli (false eye) Vision Sensory bias results in divergent displays Reflectance H. caryi Wavelength E. lateralis Lake Victoria Cichlids Vision -mechanism & maintenance Cichlids can interbreed without loss of fertility – isolated by mate choice Assortative mating is strongly determined by coloration Dull coloration, few color morphs, and low species diversity are characteristic of turbid areas… Vision shape discrimination among various fishes Lateral line neuromasts • detects vibrations • prey, predators, other fish, or obstacles Lateral line lantern fish blind cavefish relies on lateral line system more than any other sense lake trout Lateral line On some sharks, lateral line extends to head Can detect where the prey is coming from and relative speed Lateral line Developing lateral line in Zebrafish (Danio rerio) • stained for neuronal connections Lateral line lateral line placement gives clues to fishes ecology • prey • predators • habitat Electroreception Derived from sensory hair cells found in lateral lines Two main receptor types: Ampullary receptors • responsible for passive electrorecption Tuberous receptors • only found in fishes that use electric organs to generate electric field Electroreception Ampullary receptors • widespread among fishes • lampreys, chondrichthyes, lungfishes, coelacanths, sturgeons, paddlefishes, osteoglossiformes, gymnotiformes, & siluriformes • particularly abundant on elasmobranchs • identified as ampullae of Lorenzini who has higher density? Electroreception - density can change w/ development Electroreception Tuberous receptors • responsible for active electrorecption • detect electric field produced by fishes own electric organ • only in freshwater fishes • mormyrid elephantfishes & gymnotiform knifefishes Electroreception Mormyrid elephantfishes Gymnotiform knifefishes Electroreception Mormyriform elephantfishes use EODs for: • orientation • territorial interactions Electric organ discharge (EOD) • species ID • individual recognition • courtship • communicate social status Electroreception Elephant fish likely convergence Electric eel Touch and Taste Taste – probably the least developed sense in fishes • used primarily for food recognition • in and around mouth (lips & barbels) and in some cases fins Touch and Taste Taste – probably the least developed sense in fishes • used primarily for food recognition • in and around mouth (lips & barbels) and in some cases fins The gurnard uses both… Touch and Taste
