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Fish taste good too Fin rays Barbels Cirri

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Mechanoreception http://upload.wikimedia.org/wikipedia/commons/8/82/Spherical_pressure_waves.gif What is sound? How is it different in water? Two primary systems for detecting vibrations (sound) and changes in water pressure 1.Lateral line system 2.Inner ear

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Sensory hair cell Lateral line systemvibration sensing structure Sensory neuron Cilia Nucleus Synapse Neuromast Support cell Nerves Cupula

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Exposed, free standing on skin or in grooves Function depends on species/habitat Habitats with flowing water or high turbulence Few neuromasts Habitats with still or turbid water Many neuromasts Lateral line systemsuperficial neuromasts

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Individual/population level variability in superficial neuromasts Natural selection acts on sensory systems to better adapt a species to its habitat

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Shielded from large-scale water motion Better at detecting high frequency sound Lateral line systemcanal neuromasts Epidermis Scale Lateral line canal Lateral line pore NerveNeuromast

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Lateral line systemcanal neuromasts Anterior lateral line systempores or canals Uses of the lateral line system?

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Lateral line systemtoadfish example

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Lateral LineElasmobranchs

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Fish have pair of inner ear structures Two chamberstop chamber connects three semicircular canals Canals filled with fluid & contain sensory hair cells Acceleration & direction change Inner earfor balance

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Three otoliths Mostly CaCO 3 dense Otolith #1 for acceleration & equilibrium Inner earfor balance Sensory hair cells Otolith 1 3 2

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Otoliths #2-3 for hearing Lower chamber lined with sensory hair cells Sagittabiggest otolith Inner earfor hearing 1 3 2

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Inner EarPearl fish e.g.

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Magnetic Reception Sensing the Earths magnetic field for navigation Poorly studied in fishes Magnetite (FeO 4 ) & iron deposits Lab studies Important for small- & large-scale migrations

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Electric fieldsa sphere where charged particles (e -, Na +, Cl - ) experience magnetic force Salt water great conductor Organisms produce electric fields Cells maintain voltage across membranes Neurons, muscle cells Field fluctuates & attenuates with distance Electroreception What contributes most to a hiding fishs electric field?

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Ampullary ReceptorsAmpullae of Lorenzini Arise from same precursor cells as neuromasts Detect external sources Respond to gradients in field strength Sense size & distance Ancestral vertebrate characteristic Secondarily lost in Neopterygii Secondarily evolved in some teleost groups Uses? Locations?

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Ampullary receptorsdiversity

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Ray & catfish ampullary pores