11
ELECTRORECEPTION
M . V. L. BENNETT
I. Introduction . . . . . . . . . . .
11. Distribution of Electroreceptors
.
. . . . .
111. Tonic Electroreceptors . . . . . . . . .
A. Characteristics in Gymnotids and Mormyrids . . .
B. Electrical Equivalent and Input-Output Relationships
.
C. Characteristics in Catfish
. . . . . . .
D. Ampullae of Lorenzini . . . . . . . .
IV. Phasic Electroreceptors
. . . . . . . .
A. Large Receptors of Mormyrids
. . . . . .
B. Phasic Receptors of Gymnotids . . . . . .
C . Medium Receptors of Mormyrids
. . . . .
D. Phasic Receptors of Gymnarchus . . . . . .
E. Amplification and Oscillation at Phasic Receptors
. .
V. Receptor Function in Electroreception
,
.
. . .
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. 496
. 503
. 503
. 512
. 515
. 517
. 520
. 528
. 533
. 536
. 540
. 540
. 544
A. Accessory Structures and Receptor Responses to Potential
Gradients in the Environment
.
. . . . . .
B. Receptor Responses to Electric Organ Discharges
. . .
C. Central Projections of Electroreceptor Activity
.
.
.
D. Behavioral Responses to Voltage Gradients and Conductance
Changes . . . . . . . . . . . .
E. Thresholds for Receptor and Behavioral Responses .
. .
VI. Evolution of Electrosensory Systems and Electric Organs
.
.
VII. Implications for Receptor Function in General
,
. . .
References
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. . . . . . . . . . .
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555
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56a
I. INTRODUCTION
A number of groups of fish have receptors that are specialized for the
detection of electric fields (Table I ) . The existence of these electroreceptors was first clearly indicated in weakly electric fish, which
continually set up low voltage electric fields around themselves by means
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