Topic
Electrocommunication
About: Electrocommunication is a research topic. Over the lifetime, 181 publications have been published within this topic receiving 8850 citations.
Papers published on a yearly basis
Papers
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: An electric fish in the African family Mormyridae recognizes members of its own species by "listening" to electric organ discharges, which are species-specific signatures.
Abstract: An electric fish in the African family Mormyridae recognizes members of its own species by "listening" to electric organ discharges, which are species-specific signatures. Reactions of fish in the field and of individual electroreceptors to both normal and modified computer-synthesized discharges emphasize the importance of the waveform (time-domain cues) in species recognition.
250 citations
TL;DR: All electric fish studied so far can independently determine the capacitative and resistive components of objects that possess complex impedances, which allows the fish to discriminate between living and non-living matter.
Abstract: Weakly electric fish produce electric signals (electric organ discharges, EODs) with a specialised electric organ creating an electric field around their body. Objects within this field alter the EOD-induced current at epidermal electroreceptor organs, which are distributed over almost the entire body surface. The detection, localisation and analysis of objects performed by monitoring self-produced electric signals is called active electrolocation. Electric fish employ active electrolocation to detect objects that are less than 12 cm away and have electric properties that are different from those of the surrounding water. Within this range, the mormyrid Gnathonemus petersii can also perceive the distance of objects. Depth perception is independent of object parameters such as size, shape and material. The mechanism for distance determination through electrolocation involves calculating the ratio between two parameters of the electric image that the object projects onto the fish's skin. Electric fish can not only locate objects but can also analyse their electrical properties. Fish are informed about object impedance by measuring local amplitude changes at their receptor organs evoked by an object. In addition, all electric fish studied so far can independently determine the capacitative and resistive components of objects that possess complex impedances. This ability allows the fish to discriminate between living and non-living matter, because capacitance is a property of living organisms. African mormyrids and South American gymnotiforms use different mechanisms for capacitance detection. Mormyrids detect capacitance-evoked EOD waveform distortions, whereas gymnotiforms perform time measurements. Gymnotiforms measure the temporal phase shift of their EODs induced at body parts close to the object relative to unaffected body parts further away.
205 citations
TL;DR: It is shown here that predation pressure on neotropical, weakly electric fish seems to have selected for greater signal complexity, by favouring characters that have enabled further signal elaboration by sexual selection.
Abstract: Theories of sexual selection assume that predation is a restrictive, simplifying force in the evolution of animal display characters1 and many empirical studies have shown that predation opposes excessive elaboration of sexually selected traits2 In an unexpected turnaround, I show here that predation pressure on neotropical, weakly electric fish (order Gymnotiformes) seems to have selected for greater signal complexity, by favouring characters that have enabled further signal elaboration by sexual selection Most gymnotiform fish demonstrate adaptations that lower detectability of their electrolocation/communication signals by key predators A second wave phase added to the ancestral monophasic signal shifts the emitted spectrum above the most sensitive frequencies of electroreceptive predators By using playback trials with the predatory electric eel (Electrophorus electricus), I show that these biphasic signals are less detectable than the primitive monophasic signals But sexually mature males of many species in the family Hypopomidae extend the duration of the second phase of their electric signal pulses3 and further amplify this sexual dimorphism nightly during the peak hours of reproduction4 Thus a signal element that evolved for crypsis has itself been modified by sexual selection
172 citations
TL;DR: The fact that electric signals do not propagate, but exist as electrostatic fields, means that, unlike sound signals, electric organ discharges produce no echoes or reverberations.
Abstract: How do the communication discharges produced by electric fish evolve to accommodate the unique design features for the modality? Two design features are considered: first, the limited range of signaling imposed on the electric modality by the physics of signal transmission from dipole sources; and second, the absence of signal echoes and reverberations for electric discharges, which are non-propagating electrostatic fields. Electrostatic theory predicts that electric discharges from fish will have a short range because of the inverse cube law of geometric spreading around an electrostatic dipole. From this, one predicts that the costs of signaling will be high when fish attempt to signal over a large distance. Electric fish may economize in signal production whenever possible. For example, some gymnotiform fish appear to be impedance-matched to the resistivity of the water; others modulate the amplitude of their discharge seasonally and diurnally. The fact that electric signals do not propagate, but exist as electrostatic fields, means that, unlike sound signals, electric organ discharges produce no echoes or reverberations. Because temporal information is preserved during signal transmission, receivers may pay close attention to the temporal details of electric signals. As a consequence, electric organs have evolved with mechanisms for controlling the fine structure of electric discharge waveforms.
168 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 5 |
| 2020 | 3 |
| 2019 | 5 |
| 2018 | 8 |
| 2017 | 6 |
| 2016 | 6 |