electrogenesis in fishes by abdur rouf samim
TRANSCRIPT
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ELECTROGENESIS IN FISHES
ABDUR ROUF SAMIMM.Sc.(Final) FISHERY SCIENCE AND AQUACULTURE
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INTRODUCTIONElectrogenesis refers to the production of
electrical impulses in the tissues of a living organism.
Observed in all animals such as fishes, reptiles, and mammals etc.
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TYPES OY ELECTRIC FISHES Strongly electric fishes Example: Torpedo, Electrophorus etc. Weakly electric fishes Example: Raja, Gymnotus etc.
RajaElectrophorus
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Electric organs are organs specialized for the production of an electric field outside the body.
Built up from a large number of disc like cells, called electroplates.
Electroplates embedded in a jelly like extracellular material and enclosed within a compartment of connective tissue.
Diagram showing electric organs
ELECTRIC ORGANS
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DISTRIBUTION OF ELECTRIC ORGANSName of fishes Shape of electric
organLocation of electric organ
Torpedo Flat kidney shape On either side of mid-line
Malapterurus Lozenge-shape Located in skin
Raja (String ray) Spindle-shape Lying parallel to the spinal cord in the tail
Torpedo Raja
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PATTERNS OF ELECTRIC ORGAN DISCHARGESMonophasic pulses Biphasic pulses Polyphasic pulses
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KINDS OF ELECTRIC ORGAN DISCHARGE
Electrophorus: one small pulse followed by four large pulse.
Electric shark: repetition of sequence of events.
Torpedo: four large pulses which are continuously repeated.
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MECHANISM OF ELECTRIC ORGAN DISCHARGE
+ + + + + + +_ _ _ _ _ _ _
+ + - - - + + + - - + + + - - -
_ _ _ _ _ _ _ + + + + + + +
Resting phase
Action Potential Spike stage
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ReceptorSensory Nerve Fibre Brain Optic
Nerve
Electric OrganMotor Nerve
1
2
Pathways of neural control of electric organ
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FUNCTION OF ELECTRIC ORGANFood procurement DefenseSpecies and sex recognitionDirection findingCommunicationNavigation
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WHY ARE FISHES IMMUNE TO THEIR OWN ELECTRIC CURRENT ?
Got myolated nerve fibers with high degree of insulation.
Excitatory muscle fibers have high threshold of excitation.
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Referenceswww.wired.comwww.elguanche.infowww.revolvy.comwww.keywordsuggests.orgBrown, animal physiology ,2nd volume.Notes provided by Prof. Mukhtar Ahmad
Khan.
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