Topic
Jamming avoidance response
About: Jamming avoidance response is a research topic. Over the lifetime, 157 publications have been published within this topic receiving 7730 citations.
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TL;DR: A theory has been proposed which suggests that these fish, by means of their electric pulses, can locate objects if their electrical conductivity differs from that of water, and show striking features of convergent evolution.
Abstract: 1. The electric discharges of Gymnarchus niloticus and of representative species of seven genera of the Mormyridae have been examined in their natural habitat in Africa and in the laboratory. 2. Comparable investigations of the South American Gymnotidae have shown the existence of two discharge types in both these unrelated fish families. 3. The first type of electric discharge consists of very regular sequences of continuously emitted, monophasic pulses, varying from species to species in frequency, and within narrower limits from individual to individual. 4. Fish emitting this first type of pulses include Gymnarchus , Hypopomus and Eigenmannia . The frequency range for these fish lies between 60 and 400 discharges/sec. 5. The frequency does not alter with the state of excitation of the fish. The duration of individual pulses is relatively long, i.e. 2-10 msec. 6. The second type of discharge is less regular in frequency, the pulse duration much shorter and the pulse shape more complex. The individual discharge from the whole electric organ lasts about 0.2 msec, in Petrocephalus . 7. This type of discharge is found in all the examined species of the Mormyridae and in such forms as Gymnotus carapo and Staetogenes elegans . 8. The basic discharge rate of a resting mormyrid is somewhat variable and not strictly rhythmical. It usually lies between 1 and 6 pulses/sec. 9. Stimuli which excite the mormyrids cause an increase in the discharge frequency. The recorded maximum is about 130 pulses/sec. 10. Suitable stimuli can inhibit the discharges of the Mormyridae for prolonged periods. 11. In Gymnotus carapo and Staetogenes elegans the basic discharge rate is higher and of regular rhythmicity. Depending on temperature the frequencies lie between 30 and 87 pulses/sec. When these fish are excited the frequencies are increased up to 200 pulses/sec, for a short time. 12. The shape of the electric field, which is set up with each pulse around the fish, has been examined. 13. A theory has been proposed which suggests that these fish, by means of their electric pulses, can locate objects if their electrical conductivity differs from that of water. 14. These fish have shown themselves extremely sensitive to influences affecting the electric field. This has been studied by applying artificial electric stimuli, by studying the effects of conductors and non-conductors introduced into the field, and the reactions towards magnetic fields and electrostatic charges. 15. Conditioned reflex experiments with Gymnarchus niloticus and Gymnotus carapo have shown that these fish can detect the presence of a stationary magnet, and that they can discriminate between conductors and non-conductors. 16. The prey of these fish does not appear to be affected by the discharges. Inter alia , the electric pulses have a social significance. 17. This locating mechanism may be considered as an adaptation to life in turbid water. 18. Gymnotidae and Mormyridae (taken to include Gymnarchus ) show striking features of convergent evolution. 19. Unusual locomotory adaptations such as swimming by means of the dorsal fin ( Gymnarchus ), the anal fin (Gymnotidae) and ‘Gemminger9s bones’ (Mormyridae) may be considered as a means which tends to make the axis of symmetry of the fish and of its electric field coincide during active movements. 20. A new theory for the evolution of electric organs has been suggested. A major prerequisite appears to be a receptor sensitive to electrical stimulation. 21. It is suggested that special sensory and nervous differentiations of the lateralis system (‘mormyromasts’, valvulae cerebelli) are concerned with the perception and integration of electric stimuli. 22. Muscular action potentials have been recorded in the water at some distance from non-electric fish. 23. The easiest explanation for the evolution of strong electric organs would appear to start from such muscular action potentials, and proceed via weak electric organs used for orientation, to the powerful offensive and defensive electric organs.
549 citations
TL;DR: In this article, the effect on the receptors of the perturbing field due to an object depends on the electrical properties of the receptors: in the extreme cases the stimulation of the receptor is proportional either to the potential or to its second derivative.
Abstract: 1. Experiments with moving electrostatic and magnetic fields show that Gymnarchus niloticus is sensitive to a potential gradient of about 0.03 µ V./cm.
2. Alternative explanations of some previous experiments are given in terms of this high d.c. sensitivity.
3. An explanation in similar terms is given of experiments in which Gymnotus carapo is trained to detect a stationary magnet.
4. The mechanisms available for the location of objects by electric fish are reviewed. It is concluded from the results of a critical experiment (described in a succeeding section) that Gymnarchus niloticus can detect objects by the disturbance of its own electric field in the water.
5. The approximate theory of this method of object location is derived. The effect on the receptors of the perturbing field due to an object depends on the electrical properties of the receptors: in the extreme cases the stimulation of the receptors is proportional either to the potential or to its second derivative. Graphs are given showing the effect of an object on the potential and on its second derivative around the surface of the fish.
6. Experiments are described using Gymnarchus niloticus which ( a ) confirm that the mechanism of object location employs electric field distortion; ( b ) indicate the limits of the sensitivity of the fish.
7. The second derivative mode appears to be the most probable one operating in Gymnarchus . The experimentally determined limits of detection are discussed in relation to the random noise in the receptor circuit: it is concluded that both spatial and temporal integration are likely to be employed.
8. The thresholds for object location and for response to direct currents are compared: it is concluded that the same receptors are probably operating in both cases.
476 citations
01 Jun 1973-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: The electric fish Eigenmannia as discussed by the authors is able to sense objects which differ in electrical conductivity from the surrounding water by detecting distortions of the current field associated with its electric organ discharges.
Abstract: The electric fish,Eigenmannia, is able to sense objects which differ in electrical conductivity from the surrounding water by detecting distortions of the current field associated with its electric organ discharges. While resting,Eigenmannia hovers near electrically-detectable objects and follows their motions. When such objects are swung in a sinusoidal manner, the fish follows with a certain gain and phase lag. This allows one to quantify performance in “electrolocation” in terms of gain and phase values as functions of frequency of object motion, object size and distance. As these parameters reach threshold values, the gain of the animal's Following Response approaches zero while its phase lag tends toward-π. Electrolocation deteriorates under “jamming” conditions, i.e. in the presence of electric signals with frequencies near the animal's discharge frequency.Eigenmannia prevents the deterioration of electrolocation by shifting its frequency away from noise frequencies.
196 citations
TL;DR: A South American gymnotid Eigenmannia, changes the discharge frequency of its electric organ when a weak electric signal is applied to it with a frequency very close to that of its own discharge.
Abstract: 1. A South American gymnotid Eigenmannia , changes the discharge frequency of its electric organ when a weak electric signal is applied to it with a frequency very close to that of its own discharge. Otherwise, the discharge frequency is extremely constant at a fixed temperature. 2. When the frequency of the applied signal is higher or lower than that of the fish discharge, the response is a decrease or increase of the discharge frequency, respectively. When the two frequencies are exactly the same, the response fails to occur. 3. The threshold of this response is very low. In one fish it was about 3 µ V./cm.
194 citations
1 Jan 1977
184 citations
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| Year | Papers |
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| 2020 | 3 |
| 2019 | 5 |
| 2018 | 6 |
| 2017 | 1 |
| 2016 | 3 |
| 2015 | 2 |