ELECTROGENESIS IN FISHES By ABDUR ROUF SAMIM

1. ELECTROGENESIS IN FISHES
ABDUR ROUF SAMIM
M.Sc.(Final)
FISHERY SCIENCE AND
AQUACULTURE

2. INTRODUCTION
 Electrogenesis 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.

3. TYPES OY ELECTRIC FISHES
 Strongly electric fishes
Example: Torpedo, Electrophorus etc.
 Weakly electric fishes
Example: Raja, Gymnotus etc.
RajaElectrophorus

4.  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

5. DISTRIBUTION OF ELECTRIC ORGANS
Name of fishes Shape of electric organ Location 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

6. PATTERNS OF ELECTRIC ORGAN DISCHARGES
 Monophasic pulses
 Biphasic pulses
 Polyphasic pulses

7. 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.

8. MECHANISM OF ELECTRIC ORGAN DISCHARGE
+ + + + + + +
_ _ _ _ _ _ _
+ + - - - + + +
- - + + + - - -
_ _ _ _ _ _ _
+ + + + + + +
Resting phase Action Potential Spike stage

9. Receptor
Sensory
Nerve Fibre
Brain Optic Nerve
Electric Organ
Motor Nerve
1
2
Pathways of neural control of electric organ

10. FUNCTION OF ELECTRIC ORGAN
 Food procurement
 Defense
 Species and sex recognition
 Direction finding
 Communication
 Navigation

11. 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.

12. References
 www.wired.com
 www.elguanche.info
 www.revolvy.com
 www.keywordsuggests.org
 Brown, animal physiology ,2nd volume.
 Notes provided by Prof. Mukhtar Ahmad Khan.