INVESTIGATION OF ELECTRIC FISHES

• Document Type: SPECIALCOLLECTION
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): 00173502
• Release Decision: RIPPUB
• Original Classification: U
• Document Page Count: 12
• Document Creation Date: January 21, 2025
• Document Release Date: January 15, 1983
• Publication Date: February 28, 1973

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INVESTIGATION OF ELECTRIC FISHES
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28 February 1973
CONTENTS
1.
INTRODUCTION
1
2.
TECHNICAL DISCUSSION
2
3.
STATEMENT OF WORK
5
4.
PRICE AND CONTRACTUAL INFORMATION
8
5.
PERSONNEL
10
REFERENCES
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1. INTRODUCTION
In a previous proposal, it was kated that the relationship between
electroreceptors in the pattern recognition process of electric fish would
be studied. In a Midterm Report of September 1972, the phasic tuberous
asynchronic electroreceptors and the synchronous tonic ampullary electro-
receptors of the �Sternarchus albifrons, a freshwater South American weak
electric fish were described. The tonic asynchronous ampullary electro-
receptors of the same fish species were described previously. Measure-
ments were made and reported.
The studies on Gymnarchus niloticus, a freshwater African weak
electric fish, were continued, as were studies of the effect of different
anaesthetics on the electrical activity of electric fishes. The effect of D-
tubocurarine and the countereffect of neostigmine on Sternarchus albifrons
were also assessed:
Three mormyrids (Gnathonemus petersii) were obtained, a fresh-
water African weak electric fish supposed to be the most intelligent fish
(sic). The brain/body weight ratio is close to that of human beings. Pre-
viously, one fish of this species was trained to jump through a circle over
the water in order to get its food. Studies of the electric activity of these
fishes will yield added information on pattern recognition ability of electric
fishes. Based upon data generated by these studies, we now propose to
generate design and test concepts for physical analogs of the electroreceptors
of electric fish to be used in subsequent studies of underwater object detection,
identification, and position. These sensor analog simulation tests will be
planned to be performed in a plastic water tank of 18 feet diameter.
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2. TECHNICAL DISCUSSION
From previous and ongoing investigations, it was determined that
Sternarchus albifrons, a South American freshwater high-frequency weak
electric fish, has three kinds of electroreceptors:
1. synchronous tonic ampullary electric sensors
2. asynchronous tonic ampullary electric sensors
3. asynchronous phasic tuberous electric sensors
Microelectrode recordings were made from these receptors. The fish was
anaesthetized with tricaine methanesulfonate (Finquel "Ayerst") and cura-
_
rized with D-tubocurarine. Subsequently, neostigmine was used to counter-
act the long-term effect of curare. A search for an anaesthetic that will
not affect the frequency and amplitude of the electric signals emitted by
electric fish has been made. This study is in progress and preliminary
results indicate that thiopental sodium may not affect the electric signal of
Sternarchus albifrons. Both ampullary and tuberous electric sensors are
autorhythmic. Two out of three kin:Is of electric sensors act independently
of the main electric organ. This means that we deal with three transmitting
systems: a main organ and two secondary represented by the autorhythmic
activity. There are also three kinds of electroreceptors, two of which are
transmitters and receptors at the same time, and each of them may have
some finer subdivisions with regard to sensitivity, amplitude, frequency,
latency and habituation.
These electroreceoptors are part of the "lateralis system" of the fish
and the other organs related to this system like the lateral line receptors
and the free neuromasts are certainly playing an important role in pattern
recognition.
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The difference between the lateral line sensory receptors and free
neuromasts is that the first ones are connected to a common lateral line
canarand the last ones not. With all the research devoted to both of these
sensory receptors, the difference in the role of the one or the other kind
of sensory receptor has not been clarilled. However, both sensors are
related to water displacement, the fish's own movement, schooling be-
havior, and avoidance of objects or enemies.
The electric fish's other "Iateralis system" sdnsory organs that
the electric organs have not received too much attention.
Idemonstrated that on one and the same elasmobranch,
Negaprion brevirostris, (Lemon shark), two kinds of amp. unary sensory
organs exist: one that is sensitive to water displacement, and another one
that is sensitive to electric stimuli. Anatomically they looked Very much
the same, but not biochemically. This indicates the complexity of the
sensory system of certain fishes to provide the required functions required
for navigation, location of prey, identification of enemies, social interaction
in the same species, and communication.
Gymnarchus niloticus, an African freshwater medium-frequency
weak electric fish, has one ampullary type of electric sensors and two
tuberous types of electric sensors. These electric sensors have to be in-
vestigated in relation to their autorhythmicity and their role in navigation
and object location. Previous studies have demonstrated the ability of
Gymnarchus niloticus to communicate with members of their same species.
Gnathonemus petersii, an African freshwater low-frequency mor-
myrid electric fish, can be obtained and study is planned after the usual
stabilization stage. Studies by Agalides and others of electric fish sensory
systems as cited above provided a basis for describing the physical analogs
3
of tonic ampullary electroreceptors and of phasic tuberous electroreceptors
in a midterm report. Continuation of this work can establish physical
analogs for other electroreceptors and sensory receptors of the "lateralis
system" of electric fishes.
Microelectrode recordings, histology, light microscopy, electro-
microscopy, and scanning electronmicroscopy can be used to clarify the
establishment of the physical analogs.
Some studies on the sensitivity threshold of electric fishes to electric
~.����
stimuli were made by
This proposed study intends to extend this work. An extensive study
of the sensitivity of different species of electric fishes to electric stimuli
in the presence of noise and without noise will be made to find out which of
the different types of sensory systems of the different species is most ef-
fective in locating and identifying objects underwater.
For these experiments, we will use an instrumented pool facility.
The distance at which an electric fish can identify moving and stationary
objects and to communicate with specimens of its own species can be de-
ducted from the distance, the composition and size of the objects presented
to the subject and of the distance of back-playing electrodes and the applied
attenuation to the signal. By adding specific kinds and amplitudes of noise,
we will be able to find out how well the fish can extract the signal from
noise.
Having all of the previously mentioned data, we can proceed to the
establishment of an underwater pattern recognition diagram. The established
physical analogs of electric sensors and cross correlation will be proposed
as a means for identifying objects.
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3. STATEMENT OF WORK
/will provide
the personnel, services and material necessary to conduct an investigation
of electric fishes. The tasks for Phase I and Phase LI will be performed
as outlined below.
����
PHASE I
1. Investigate the ability of freshwater electric fishes to recognize
patterns under water and how effectively they can differentiate
between different parameters when navigating. It is proposed
to use three or four of the following kinds of freshwater weak
electric fishes:
a. Sternarchus albifrons, high signal rate electric fish
with its frequency influenced only by change in the
tank water temperature; region of origin - subtropical,
tropical and equatorial South America.
b. Gymnarchus niloticus, medium fixed signal rate electric
fish with its frequency not influenced by change of tank
water temperature; region of origin - subtropical,
tropical, and equatorial Africa.
c. Gymnotus carapo, variable medium signal rate electric
fish, region of origin - subtropical, tropical, and
equatorial South America.
d. Gnathonemus petersii, a variable low signal rate electric
fish of the mormyridae family; region of origin - sub-
tropical, tropical, and equatorial Africa.
Microelectrode recording, histology, light microscopy, electro-
microscopy and scanning electromicroscopy will be used as ne-
cessary to elucidate and establish the interrelation of electric
receptors.
3. Report. A report of the six months' study will be submitted
at the end of Phase I.
PHASE II
.1. The threshold of electric signal stimuli eliciting a behavioral
7 response in electric fishes will be investigated for:
a. fishe's own signal recorded on magnetic tape and played
back and attenuated.
b. same species but another subject fish's electric signal
recorded on magnetic tape, played back and attenuated
c. sinusoidal electric signal with same repetition rate as
the fish's own signal or slightly changed and attenuated
d. signals as in (1) and (2) but with a noise source like
gaussian noise and varying amplitude will be added
through another pair of electrodes in the same water
tank.
These experiments will be carried out in a special round tank
of 18 feet diameter by 2 feet high and placed in a special tank
facility.
2. From all these results, the distance will be calculated at which
an electric fish could detect its own or another electric signal
considering the attenuation, the distortion of the signal in water,
and eventually the added noise.
3. Physical analogs will be established for some of the electro-
receptors, displacement receptors, and other lateral line
type of receptors.
A diagram for an underwater pattern recognition simulation
of the electric fish's electric sensors system, using their
physical analogs and a special cross-correlation data pro-
cessing, will be submitted. A special instrumented under-
water pool facility and computer simulating equipment will
be considered for use for this proposition.
5. Reports. Financial monthly reports will be submitted. A
final report will be furnished one year after contract award.
The schedule for the proposed research is outlined in Fig. 5
� with the estimated time for carrying out each phase.
TASK
- CALENDAR MONTILS
1
2
3
5
6
7
8
9
10
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I ' PHASE I
1.. Investigate pattern recognition ability and
navigation ability of three or four different
electric fish species.
2. Investigate the interrelation of electric
� receptors.
3. Report
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1. Establish the threshold of electric stimuli
eliciting a behavioral response in electric
fish under different conditions.
, 2. Establish the distance at which electric
signals can be detected by electric fish.
3. Establish physical analogs of the electric
receptors.
4. Design a diagram for an underwater simu-
lation of the fish's electrosonsory system. '
5. Final report ,.
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Fig. 5. Program Schedule.
4. PRICE AND CONTRACTUAL INFORMATION
/suggests that the proposed program
be conducted over a one-year period under a cost-plus fixed-fee contract.
The estimated costs for this program are shown at the end of this section.
�
The labor costs used in this proposal are based upon the current
average rate of the level of personnel expected to be employed in the pro-
posed effort. No premium for direct overtime expense has been included
in this proposal.
The overhead rate used in this proposal is provisional and con-
sists of all indirect costs and is adjusted for
assumed unallowable costs. Overhead rates will be adjusted at the end
of the fiscal year I to actual costs excluding
disallowables, as determined by Government audit.
-1is under the audit cognizance of the
Defense Contract Audit Agency,
Unless previously withdrawn in writing, this proposal will remain
valid for ninety days from the date on the cover.
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ESTIMATED COST FOR A TWELVE-MONTH PROGRAM
Man-Hours
PERSONNEL COSTS
Scientist 41 1210
Scientist 23 '� 40
Scientist 12 100
Technical Typist 96
OVERHEAD @
FRINGE BENEFITS @
TRAVEL: Phase
Phase II
MATERIALS: Phase
Phase II
TOTAL DIRECT COST & OVERHEAD
GENERAL & ADMINISTRATIVE EXPENSE @
TOTAL ESTIMATED COST
FIXED FEE
TOTAL ESTIMATED COST PLUS FIXED FEE
0
5. PERSONNEL
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