Communication signals and sound production mechanisms of mormyrid electric fish

1999 ◽  
Vol 202 (10) ◽  
pp. 1417-1426 ◽  
Author(s):  
J.D. Crawford ◽  
X. Huang
Keyword(s):  
Sound Production ◽  
Electric Organ ◽  
Trunk Muscles ◽  
Sexually Dimorphic ◽  
Behavioral Experiments ◽  
Communication Signals ◽  
Species Specific ◽  
Electric Organ Discharges ◽  
Electrical Stimuli ◽  
Weakly Electric

The African weakly electric fishes Pollimyrus isidori and Pollimyrus adspersus (Mormyridae) produce elaborate acoustic displays during social communication in addition to their electric organ discharges (EODs). In this paper, we provide new data on the EODs of these sound-producing mormyrids and on the mechanisms they use to generate species-typical sounds. Although it is known that the EODs are usually species-specific and sexually dimorphic, the EODs of closely related sound-producing mormyrids have not previously been compared. The data presented demonstrate that there is a clear sexual dimorphism in the EOD waveform of P. isidori. Females have a multi-phasic EOD that is more complex than the male's biphasic EOD. In this respect, P. isidori is similar to its more thoroughly studied congener P. adspersus, which has a sexually dimorphic EOD. The new data also reveal that the EODs of these two species are distinct, thus showing for the first time that species-specificity in EODs is characteristic of these fishes, which also generate species-specific courtship sounds. The sound-generating mechanism is based on a drumming muscle coupled to the swimbladder. Transverse sections through decalcified male and female P. adspersus revealed a muscle that envelops the caudal pole of the swimbladder and that is composed of dorso-ventrally oriented fibers. The muscle is five times larger in males (14.5+/−4.4 microl, mean +/− s.d.) than in females (3.2+/−1.8 microl). The fibers are also of significantly larger diameter in males than in females. Males generate courtship sounds and females do not. The function of the swimbladder muscle was tested using behavioral experiments. Male P. adspersus normally produce acoustic courtship displays when presented with female-like electrical stimuli. However, local anesthesia of the swimbladder muscle muted males. In control trials, males continued to produce sounds after injection of either lidocaine in the trunk muscles or saline in the swimbladder muscles.

scholarly journals Sound production to electric discharge: sonic muscle evolution in progress in Synodontis spp. catfishes (Mochokidae)

2014 ◽  
Vol 281 (1791) ◽  
pp. 20141197 ◽  
Author(s):  
Kelly S. Boyle ◽  
Orphal Colleye ◽  
Eric Parmentier
Keyword(s):  
Sound Production ◽  
Electric Organ ◽  
Species Level ◽  
Electric Discharges ◽  
Swim Bladder ◽  
Auditory Thresholds ◽  
Sonic Muscle ◽  
Species Specific ◽  
Electric Organ Discharges ◽  
Muscle Evolution

Elucidating the origins of complex biological structures has been one of the major challenges of evolutionary studies. Within vertebrates, the capacity to produce regular coordinated electric organ discharges (EODs) has evolved independently in different fish lineages. Intermediate stages, however, are not known. We show that, within a single catfish genus, some species are able to produce sounds, electric discharges or both signals (though not simultaneously). We highlight that both acoustic and electric communication result from actions of the same muscle. In parallel to their abilities, the studied species show different degrees of myofibril development in the sonic and electric muscle. The lowest myofibril density was observed in Synodontis nigriventris , which produced EODs but no swim bladder sounds, whereas the greatest myofibril density was observed in Synodontis grandiops , the species that produced the longest sound trains but did not emit EODs. Additionally, S. grandiops exhibited the lowest auditory thresholds. Swim bladder sounds were similar among species, while EODs were distinctive at the species level. We hypothesize that communication with conspecifics favoured the development of species-specific EOD signals and suggest an evolutionary explanation for the transition from a fast sonic muscle to electrocytes.

scholarly journals Evidence for mutual allocation of social attention through interactive signaling in a mormyrid weakly electric fish

2018 ◽  
Vol 115 (26) ◽  
pp. 6852-6857 ◽  
Author(s):  
Martin Worm ◽  
Tim Landgraf ◽  
Julia Prume ◽  
Hai Nguyen ◽  
Frank Kirschbaum ◽  
...  
Keyword(s):  
Cognitive Abilities ◽  
Electric Fish ◽  
Electric Organ ◽  
Social Attention ◽  
Weakly Electric Fish ◽  
Vertebrate Lineage ◽  
Discharge Patterns ◽  
Species Specific ◽  
Electric Organ Discharges ◽  
Weakly Electric

Mormyrid weakly electric fish produce electric organ discharges (EODs) for active electrolocation and electrocommunication. These pulses are emitted with variable interdischarge intervals (IDIs) resulting in temporal discharge patterns and interactive signaling episodes with nearby conspecifics. However, unequivocal assignment of interactive signaling to a specific behavioral context has proven to be challenging. Using an ethorobotical approach, we confronted single individuals of weakly electricMormyrus rume proboscirostriswith a mobile fish robot capable of interacting both physically, on arbitrary trajectories, as well as electrically, by generating echo responses through playback of species-specific EODs, thus synchronizing signals with the fish. Interactive signaling by the fish was more pronounced in response to a dynamic echo playback generated by the robot than in response to playback of static random IDI sequences. Such synchronizations were particularly strong at a distance corresponding to the outer limit of active electrolocation, and when fish oriented toward the fish replica. We therefore argue that interactive signaling through echoing of a conspecific’s EODs provides a simple mechanism by which weakly electric fish can specifically address nearby individuals during electrocommunication. Echoing may thus enable mormyrids to mutually allocate social attention and constitute a foundation for complex social behavior and relatively advanced cognitive abilities in a basal vertebrate lineage.

scholarly journals The weakly electric fish, Apteronotus albifrons, actively avoids experimentally induced hypoxia

2021 ◽  
Author(s):  
Stefan Mucha ◽  
Lauren J. Chapman ◽  
Rüdiger Krahe
Keyword(s):  
Active Avoidance ◽  
Electric Fish ◽  
Electric Organ ◽  
The Other ◽  
Weakly Electric Fish ◽  
Dissolved Oxygen Concentration ◽  
Shuttle Box ◽  
Freshwater Habitats ◽  
Electric Organ Discharges ◽  
Weakly Electric

AbstractAnthropogenic environmental degradation has led to an increase in the frequency and prevalence of aquatic hypoxia (low dissolved oxygen concentration, DO), which may affect habitat quality for water-breathing fishes. The weakly electric black ghost knifefish, Apteronotus albifrons, is typically found in well-oxygenated freshwater habitats in South America. Using a shuttle-box design, we exposed juvenile A. albifrons to a stepwise decline in DO from normoxia (> 95% air saturation) to extreme hypoxia (10% air saturation) in one compartment and chronic normoxia in the other. On average, A. albifrons actively avoided the hypoxic compartment below 22% air saturation. Hypoxia avoidance was correlated with upregulated swimming activity. Following avoidance, fish regularly ventured back briefly into deep hypoxia. Hypoxia did not affect the frequency of their electric organ discharges. Our results show that A. albifrons is able to sense hypoxia at non-lethal levels and uses active avoidance to mitigate its adverse effects.

Active electrolocation of objects in weakly electric fish

1999 ◽  
Vol 202 (10) ◽  
pp. 1205-1215 ◽  
Author(s):  
G. von der Emde
Keyword(s):  
Electric Fish ◽  
Electric Organ ◽  
Weakly Electric Fish ◽  
Entire Body ◽  
Body Parts ◽  
Surrounding Water ◽  
Two Parameters ◽  
Electric Organ Discharges ◽  
Electric Signals ◽  
Weakly Electric

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.

Behavioral evidence for post-pause reduced responsiveness in the electrosensory system ofGymnotus carapo

2002 ◽  
Vol 205 (16) ◽  
pp. 2525-2533 ◽  
Author(s):  
Stefan Schuster
Keyword(s):  
High Frequency ◽  
Sampling Rate ◽  
Sensory System ◽  
Low Frequency ◽  
Electric Organ ◽  
Weakly Electric Fish ◽  
Sensory Stimuli ◽  
Novelty Response ◽  
Electric Organ Discharges ◽  
Electrical Stimuli

SUMMARYGymnotiform weakly electric fish find their way in the dark using a continuously operating active sensory system. An electric organ generates a continuous train of discharges (electric organ discharges, EODs), and tuberous high-frequency electroreceptors monitor the pattern of transcutaneous current flow associated with each EOD. Here, I report that a prior interruption to the continuous train of EODs dramatically affects a response shown by many pulse-type gymnotids. In this so-called novelty response, fish normally raise their electrosensory sampling rate in response to novel sensory stimuli. The gymnotid Gymnotus carapo was induced to pause its EODs briefly, and the novelty response to sensory stimuli given post-pause was analyzed. Mechanosensory stimuli given as early as 20 EODs after a pause elicited clear novelty responses, but strong high-frequency electrical stimuli were ineffective at this time. Moreover, high-frequency electrical stimuli remained less efficient in eliciting normal-sized responses until approximately 2000 EODs, or 40s, after a pause. The post-pause inefficiency of high-frequency stimuli was not due to an inappropriate choice of intensity or their temporal patterning and did not result from the stimulation that caused the pausing. Low-frequency stimuli that also recruited ampullary electroreceptors were more efficient than high-frequency stimuli in eliciting post-pause responses. These findings show that continuous activity is required either to maintain sensitivity to high-frequency electrical stimuli or to ensure that such stimuli are able to modulate efficiently the pacemaker that sets the discharge frequency.

Evoked chirping in the weakly electric fish Apteronotus leptorhynchus: a quantitative biophysical analysis

1993 ◽  
Vol 71 (11) ◽  
pp. 2301-2310 ◽  
Author(s):  
Günther K. H. Zupanc ◽  
Leonard Maler
Keyword(s):  
Electric Organ Discharge ◽  
Electric Organ ◽  
Stimulus Onset ◽  
Weakly Electric Fish ◽  
Apteronotus Leptorhynchus ◽  
Biophysical Analysis ◽  
Absolute Amplitude ◽  
Electric Organ Discharges ◽  
Gymnotiform Fish ◽  
Weakly Electric

Apteronotus leptorhynchus, a gymnotiform fish, produces highly regular electric organ discharges of 600–1000 Hz. Short-term modulations of the electric organ discharge ("chirps") were elicited by imitating the discharges of neighboring fish. Chirps displayed an increase in frequency of approximately 100 Hz, a duration of about 15 ms, and an absolute amplitude of 0.5–2 mV. Since, similar to natural conditions, chirps summated with the beat caused by interference of the fish's own electric organ discharge and the imitating discharge, the size and shape of the chirp's amplitude envelope varied greatly according to its phase relative to the beat cycle; however, the frequency of the chirp amplitude modulation was always 50–100 Hz. All 21 males examined chirped, but their rate of chirping varied considerably (range 2–59 chirps/30 s; mean 22 chirps/30 s). In contrast, only one out of nine females chirped (mean 0.25 chirps/30 s). The latency between stimulus onset and first chirp was variable and often long (range 1.0–25.0 s; median 3.3 s). We propose that chirps are not a sensory reflex but a communicatory behavior regulated by hypothalamic peptidergic input.

scholarly journals Spatial and temporal distribution of Gymnorhamphichthys rondoni (Gymnotiformes: Rhamphichthyidae) in a long-term study of an Amazonian terra firme stream, Leticia - Colombia

2019 ◽  
Vol 17 (3) ◽  
Author(s):  
Carolina Escamilla-Pinilla ◽  
José Iván Mojica ◽  
Jorge Molina
Keyword(s):  
Site Fidelity ◽  
Nearest Neighbor ◽  
Electric Organ ◽  
Temporal Distribution ◽  
Terra Firme ◽  
Water Conductivity ◽  
Long Term Study ◽  
Electric Fishes ◽  
Electric Organ Discharges ◽  
Weakly Electric

ABSTRACT Weakly electric fishes continually emit electric organ discharges (EOD) as a means of communication and localization of objects in their surroundings. Depending on water conductivity, the amplitude of the electric field generated is known to increase with decreases in electrical conductivity of the water. In Amazonian terra firme streams, water conductivity is extremely low and fluctuates constantly due to local and regional rains. In this context, the space between freely moving weakly electric fishes may be expected to decrease, on average, with an increase in water conductivity. To test this hypothesis, we recorded the positions at rest of the sand-dwelling fish Gymnorhamphichthys rondoni in a terra firme stream for several days in alternating months, over two years. Based on daily nearest neighbor distances among individual fish in a grid, we found a uniform temporal distribution pattern (which was not affected by water conductivity) indicative of site fidelity. Here we highlight the role of other factors that could influence resting site fidelity.

Changes in electric organ discharge after pausing the electromotor system of Gymnotus carapo

2000 ◽  
Vol 203 (9) ◽  
pp. 1433-1446 ◽  
Author(s):  
S. Schuster
Keyword(s):  
Electric Organ Discharge ◽  
Amplitude Ratio ◽  
Electric Organ ◽  
Recovery Phase ◽  
Weakly Electric Fish ◽  
Electromotor System ◽  
Phase Amplitude ◽  
Electric Organ Discharges ◽  
Induced Changes ◽  
Weakly Electric

During their entire lives, weakly electric fish produce an uninterrupted train of discharges to electrolocate objects and to communicate. In an attempt to learn about activity-dependent processes that might be involved in this ability, the continuous train of discharges of intact Gymnotus carapo was experimentally interrupted to investigate how this pausing affects post-pause electric organ discharges. In particular, an analysis was conducted of how the amplitude and relative timing of the three major deflections of the complex discharge change over the course of the first 1000 post-pause discharges. The dependence of these variables on the duration of the preceding pause and on water temperature is analysed. In addition, pause-induced small reverberations at the end of the discharge are described. Common to all amplitude changes is a fast initial decrease in amplitude with a slow recovery phase; amplitude changes scale with the duration of the preceding pause and are independent of the interdischarge interval. The absence of changes in the postsynaptic-potential-derived first phase of the discharge together with changes in the amplitude ratio of the third and fourth deflections suggest that the amplitude changes are mainly due to pause-induced changes in the inner resistance of the electric organ. A model is formulated that approximates the pattern of amplitude changes. The post-pause changes described here may provide a new way to test current models of complex discharge generation in Gymnotus carapo and illustrate the speed at which changes of an electric organ discharge can take place.

Echo response to chirping in the weakly electric brown ghost knifefish (Apteronotus leptorhynchus): role of frequency and amplitude modulations

2011 ◽  
Vol 89 (6) ◽  
pp. 498-508 ◽  
Author(s):  
José Antonio Gama Salgado ◽  
Günther K.H. Zupanc
Keyword(s):  
Electric Organ Discharge ◽  
Electric Organ ◽  
The Other ◽  
Electric Discharges ◽  
Apteronotus Leptorhynchus ◽  
Electric Organ Discharges ◽  
Frequency Modulations ◽  
Brown Ghost Knifefish ◽  
Weakly Electric

Teleost fish of the order Gymnotiformes are distinguished by their ability to produce electric discharges by means of specialized organs. These electric organ discharges serve various behavioral functions, including communication. During such electric interactions, male brown ghost knifefish ( Apteronotus leptorhynchus (Ellis in Eigenmann, 1912)) generate several types of transient frequency and amplitude modulations (“chirps”) of the otherwise nearly constant discharges. Previous studies have shown that the chirps generated by one individual follow those of the other with a preferred latency of approximately 500–1000 ms. As demonstrated in the present study, signals consisting of either frequency modulations or amplitude modulations are able to trigger this echo response. Signals composed of just amplitude modulations are effective in triggering an echo response only if the reduction in amplitude is large (approximately 40%, relative to baseline of the electric organ discharge of the emitting fish). By contrast, in frequency-modulated signals, a maximum frequency increase as small as 1.2% relative to baseline frequency is sufficient to trigger an echo response. This remarkable sensitivity might be an adaptation for the detection of so-called type-2 chirps, as chirps of this type are composed of rather small frequency increases and negligible amplitude modulations. In line with this hypothesis is the observation that during electric interactions of two fish, the generation of these chirps dominates the production of any of the other five chirp types known.

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