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Journal articles on the topic 'Mormyrid'

Author: Grafiati

Published: 5 June 2025

Last updated: 15 July 2025

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1

Nambil, Adjibade Kayodé, Alphonse Adite, Hamidou Arame, Imorou Rachad Sidi, and Sonon Stanislas Pejanos. "Biodiversity and Community Structure of Mormyridae (Pisces: Teleostei: Osteoglossiformes) from Niger River in Northern Benin: Threats, Conservation and Valorization Perspectives." International Journal of Sciences Volume 8, no. 2019-05 (2019): 106–16. https://doi.org/10.5281/zenodo.3350723.

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Mormyrid fishes are of great commercial and economic importance in the artisanal fisheries of the Niger River in Benin. We investigated species composition and community structure of this taxa in order to contribute to species management and sustainable exploitation. Mormyrid individuals were collected monthly from February 2015 to July 2016 using cast nets, gill nets and seines. Among a total of 6825 individuals collected, eleven (11) species belonging to 9 genera were inventoried. Numerically, Marcusenius senegalensis dominated the fish assemblages and made 43.74% of the mormyrid sub-community followed by Mormyrus macrophthalmus (14.87%), Hyperopisus bebe, (11.43%), Petrocephalus bovei (11.21%), Mormyrus rume (8.54%) and Hippopotamyrus pssittacus (4.69%). The Shannon-Weaver index of species diversity was moderate and reached H'=2.54. Overall, percentage occurrences (PO) of Mormyrids in the 5 selected sites ranged between 40 and 100%, with Marcusenius senegalensis (PO=100%) and Hyperopisus bebe (PO=100%) widely distributed in all 5 sites. In the Niger River, Mormyrid abundances significantly (r=0.70; P<0.01) increased with dissolved oxygen. The overexploitation and other antropogenic disturbances such as domestic uses (ditch cleanings, clothe washings, bathings), invasion of floating plants (Echhornia crassipes), sand dragging, human wastes dumping, the use of chemical fertilizers and pesticides for adjacent agriculture etc. constituted some major threats for the growth and survival of the Mormyrids in the Niger River. The results of this study will contribute to design a holistic species management scheme that includes habitat protection, species conservation and valorization.Read Complete Article at ijSciences: V82019052068 AND DOI: http://dx.doi.org/10.18483/ijSci.2068

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2

Simanovsky, Sergey, Dmitry Medvedev, Fekadu Tefera, and Alexander Golubtsov. "Derived karyotypes in two elephantfish genera (Hyperopisus and Pollimyrus): lowest chromosome number in the family Mormyridae (Osteoglossiformes)." Comparative Cytogenetics 15, no. 4 (2021): 345–54. http://dx.doi.org/10.3897/compcytogen.v15.i4.67681.

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The African weakly electric elephantfish family Mormyridae comprises 22 genera and almost 230 species. Up-to-date cytogenetic information was available for 17 species representing 14 genera. Here we report chromosome number and morphology in Hyperopisus bebe (Lacepède, 1803) and Pollimyrus isidori (Valenciennes, 1847) collected from the White Nile system in southwestern Ethiopia. Both taxa displayed the diploid chromosome number 2n = 40, but they differed in fundamental numbers: FN = 66 in H. bebe and FN = 72 in P. isidori; previously the same diploid chromosome number 2n = 40 was reported in an undescribed species of Pollimyrus Taverne, 1971 (FN = 42) from the same region. Our results demonstrate that not only pericentric inversions, but fusions also played a substantial role in the evolution of the mormyrid karyotype structure. If the hypothesis that the karyotype structure with 2n = 50–52 and prevalence of the uni-armed chromosomes close to the ancestral condition for the family Mormyridae is correct, the most derived karyotype structures are found in the Mormyrus Linnaeus, 1758 species with 2n = 50 and the highest number of bi-armed elements in their compliments compared to all other mormyrids and in Pollimyrus isidori with the highest number of bi-armed elements among the mormyrids with 2n = 40.

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Simanovsky, Sergey, Dmitry Medvedev, Fekadu Tefera, and Alexander Golubtsov. "Derived karyotypes in two elephantfish genera (Hyperopisus and Pollimyrus): lowest chromosome number in the family Mormyridae (Osteoglossiformes)." Comparative Cytogenetics 15, no. (4) (2021): 345–54. https://doi.org/10.3897/compcytogen.v15.i4.67681.

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The African weakly electric elephantfish family Mormyridae comprises 22 genera and almost 230 species. Up-to-date cytogenetic information was available for 17 species representing 14 genera. Here we report chromosome number and morphology in Hyperopisus bebe (Lacepède, 1803) and Pollimyrus isidori (Valenciennes, 1847) collected from the White Nile system in southwestern Ethiopia. Both taxa displayed the diploid chromosome number 2n = 40, but they differed in fundamental numbers: FN = 66 in H. bebe and FN = 72 in P. isidori; previously the same diploid chromosome number 2n = 40 was reported in an undescribed species of Pollimyrus Taverne, 1971 (FN = 42) from the same region. Our results demonstrate that not only pericentric inversions, but fusions also played a substantial role in the evolution of the mormyrid karyotype structure. If the hypothesis that the karyotype structure with 2n = 50–52 and prevalence of the uni-armed chromosomes close to the ancestral condition for the family Mormyridae is correct, the most derived karyotype structures are found in the Mormyrus Linnaeus, 1758 species with 2n = 50 and the highest number of bi-armed elements in their compliments compared to all other mormyrids and in Pollimyrus isidori with the highest number of bi-armed elements among the mormyrids with 2n = 40.

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4

de Ruiter, Martijn M., Chris I. De Zeeuw, and Christian Hansel. "Voltage-Gated Sodium Channels in Cerebellar Purkinje Cells of Mormyrid Fish." Journal of Neurophysiology 96, no. 1 (2006): 378–90. http://dx.doi.org/10.1152/jn.00906.2005.

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Cerebellar Purkinje cells of mormyrid fish differ in some morphological as well as physiological parameters from their counterparts in mammals. Morphologically, Purkinje cells of mormyrids have larger dendrites that are characterized by a lower degree of branching in the molecular layer. Physiologically, there are differences in electrophysiological response patterns that are related to sodium channel activity: first, sodium spikes in mormyrid Purkinje cells have low amplitudes, typically not exceeding 30 mV. Second, the response to climbing fiber stimulation in mormyrid Purkinje cells does not consist of a complex spike (with an initial fast sodium spike) as in mammals, but instead it consists of an all-or-none excitatory postsynaptic potential, the so-called climbing fiber response. Because of these unique properties, we have begun to characterize mormyrid Purkinje cells electrophysiologically. In this study, we provide a description of voltage-gated Na+ channels and conductances in Purkinje cells of the mormyrid fish Gnathonemus petersii. Various types of Na+ channel α-subunits, i.e., Nav1.1, Nav1.2, and Nav1.6, have been described in rodent Purkinje cells. Using immunohistochemical techniques, we found that these subunits are present in Purkinje cells of mormyrids. To test whether these Na+ channel subunits can mediate fast inactivating and resurgent Na+ currents in Gnathonemus Purkinje cells, we conducted patch-clamp recordings in acutely dissociated cells and in cerebellar slices. Both types of Na+ currents could be measured in rat and fish Purkinje cells. These data show that, despite prominent differences in electrophysiological response characteristics, Purkinje cells of rats and mormyrids share the same voltage-gated Na+ conductances.

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5

SOULEY, S. M. N. "First Assessment of Mormyridae diversity and abundance in the Niger River at Niamey, Niger." Moroccan Journal of Agricultural Sciences 5, no. 4 (2025): 225–31. https://doi.org/10.5281/zenodo.14724133.

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To assessment Mormyridae diversity and abundance in the  Niamey fisheries on the Niger River, a study was conducted from August to November 2022. Fish data were collected bimonthly from artisanal fishing landings using gillnets, sparrowhawk nets, baited traps, and baited longlines. A total of 1279 individuals from fifteen species across nine genera were inventoried. Numerically, Mormyrus rume dominated the fish assemblages, comprising 29.9% of the mormyrid sub-community, followed by Marcusenius cyprinoides (15.0%), Campylomormyrus tamandua (12.9%), Marcusenius senegalensis (0.08%), Petrocephalus bovei (0.08%) and Hippopotamyrus pictus (0.16%). The Shannon-Weaver index of species diversity was moderate, reaching H' = 2.96. Major threats to the growth and survival of Mormyrids in the Niger River included over-exploitation and anthropogenic disturbances such as domestic uses (e.g., ditch cleaning, clothes washing, bathing), invasion of floating plants (Echhornia crassipes), sand dragging, human waste dumping and the use of chemical fertilizers and pesticides in adjacent agriculture. The results of this study will contribute to the design of a holistic species management scheme that includes habitat protection, species conservation and valorisation.

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6

Simanovsky, Sergey, Dmitry Medvedev, Fekadu Tefera, and Alexander Golubtsov. "First cytogenetic information for five Nilotic elephantfishes and a problem of ancestral karyotype of the family Mormyridae (Osteoglossiformes)." Comparative Cytogenetics 14, no. 3 (2020): 387–97. http://dx.doi.org/10.3897/compcytogen.14i3.52727.

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The elephantfish family Mormyridae is the most diverse lineage of the primitive teleostean clade Osteoglossomorpha distributed in inland waters of all continents except Antarctica and Europe. The family Mormyridae is endemic to Africa and includes 22 genera and almost 230 species. The evolutionary radiation of mormyrids most probably should be attributed to their capability of both generating and receiving weak electric signals. Up-to-date cytogenetic studies have revealed substantial karyotype differentiation among the nine investigated elephantfish species and genera (a single species studied per each genus). In the present study, karyotypes of five species representing five mormyrid genera (four unexplored ones) collected from the White Nile system in southwestern Ethiopia are described for the first time. The results show substantial variety of the diploid chromosome and fundamental numbers: 2n = 48 and FN = 54 in Brevimyrus niger (Günther, 1866), 2n = 50 and FN = 72 in Cyphomyrus petherici (Boulenger, 1898), 2n = 50 and FN = 78 in Hippopotamyrus pictus (Marcusen, 1864), 2n = 50 and FN = 76 in Marcusenius cyprinoides (Linnaeus, 1758), 2n = 52 and FN = 52 in Mormyrops anguilloides (Linnaeus, 1758). Karyotype structure in the latter species seems to be close to the ancestral condition for the family. This hypothesis is discussed in the light of available data on karyotype diversity and phylogeny of mormyrids.

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7

Simanovsky, Sergey, Dmitry Medvedev, Fekadu Tefera, and Alexander Golubtsov. "First cytogenetic information for five Nilotic elephantfishes and a problem of ancestral karyotype of the family Mormyridae (Osteoglossiformes)." Comparative Cytogenetics 14, no. (3) (2020): 387–97. https://doi.org/10.3897/CompCytogen.14i3.52727.

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The elephantfish family Mormyridae is the most diverse lineage of the primitive teleostean clade Osteoglossomorpha distributed in inland waters of all continents except Antarctica and Europe. The family Mormyridae is endemic to Africa and includes 22 genera and almost 230 species. The evolutionary radiation of mormyrids most probably should be attributed to their capability of both generating and receiving weak electric signals. Up-to-date cytogenetic studies have revealed substantial karyotype differentiation among the nine investigated elephantfish species and genera (a single species studied per each genus). In the present study, karyotypes of five species representing five mormyrid genera (four unexplored ones) collected from the White Nile system in southwestern Ethiopia are described for the first time. The results show substantial variety of the diploid chromosome and fundamental numbers: 2n = 48 and FN = 54 in Brevimyrus niger (Günther, 1866), 2n = 50 and FN = 72 in Cyphomyrus petherici (Boulenger, 1898), 2n = 50 and FN = 78 in Hippopotamyrus pictus (Marcusen, 1864), 2n = 50 and FN = 76 in Marcusenius cyprinoides (Linnaeus, 1758), 2n = 52 and FN = 52 in Mormyrops anguilloides (Linnaeus, 1758). Karyotype structure in the latter species seems to be close to the ancestral condition for the family. This hypothesis is discussed in the light of available data on karyotype diversity and phylogeny of mormyrids.

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8

Sullivan, John, Sebastien Lavoue, and Carl D. Hopkins. "Cryptomyrus: a new genus of Mormyridae (Teleostei, Osteoglossomorpha) with two new species from Gabon, West-Central Africa." ZooKeys 561 (February 8, 2016): 117–50. https://doi.org/10.3897/zookeys.561.7137.

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We use mitochondrial and nuclear sequence data to show that three weakly electric mormyrid fish specimens collected at three widely separated localities in Gabon, Africa over a 13-year period represent an unrecognized lineage within the subfamily Mormyrinae and determine its phylogenetic position with respect to other taxa. We describe these three specimens as a new genus containing two new species. Cryptomyrus, new genus, is readily distinguished from all other mormyrid genera by a combination of features of squamation, morphometrics, and dental attributes. Cryptomyrus ogoouensis, new species, is differentiated from its single congener, Cryptomyrus ona, new species, by the possession of an anal-fin origin located well in advance of the dorsal fin, a narrow caudal peduncle and caudal-fin lobes nearly as long as the peduncle. In C. ona, the anal-fin origin is located only slightly in advance of the dorsal fin, the caudal peduncle is deep and the caudal-fin lobes considerably shorter than the peduncle. Continued discovery of new taxa within the "Lower Guinea Clade" of Mormyridae highlights the incompleteness of our knowledge of fish diversity in West-Central Africa. We present a revised key to the mormyrid genera of Lower Guinea.

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Onimisi, Meriyamoh Mero, Mutiat Motolani Salaudeen, Khadijat Abubakar, and Caleb Ojochegbe Obaje. "Growth Allometry and Condition Factor of Some Mormyrids in Lower River Niger at Idah, Kogi State, Central Nigeria." International Journal of Life Science and Agriculture Research 04, no. 06 (2025): 374–80. https://doi.org/10.5281/zenodo.15582858.

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The study examined the growth allometry and condition factor of six Mormyrids of lower River Niger at Idah, Kogi State of central Nigeria. Three hundred and thirty two (332) mormyrids namely Mormyrus rume, Mormyrus macrophthalmus, Mormyrops deliciosus, Hyperopisus bebe occidentalis, Gnathonemus petersii and Pollimyrus isidori were obtained monthly from the local fishermen between June 2024 and November 2024.The fish were caught using 5.1 cm and 7.3 cm gill nets as well as traditional valved basket traps. The collected specimens were transported in ice-packed plastic containers to maintain freshness. Species identification was carried out in the laboratory using established taxonomic references. Standard length and body weight of the specimens were measured to the nearest 0.1cm and 0.1g respectively. The length-weight relationship (LWR) was determined using the equation W = <sub>a</sub>L<sup>b</sup>, while condition factor was evaluated using the equation K = 100 × W/L<sup>3.</sup> Results revealed variations in LWR among species with M rume and P. isidori exhibiting positive allometric growth having b value of 3.1 and 3.2 respectively, M. macrophthalmus and G. petersii showed isometric growth (b = 3) while M. deliciosus and H. bebe occidentalis displayed negative allometry of 2.9 and 2.7 respectively. The condition factor analysis revealed significant differences (P < 0.05) among the species. G. petersii exhibited the highest condition factor (1.67) while M. deliciosus had the lowest (0.72). The findings highlighted the need for targeted conservation strategies to protect critical habitats and maintain resource availability, particularly for species with lower condition factors. Mitigating environmental stressors such as pollution and habitat degradation are essential for sustaining the health and growth potential of Mormyrid species in the lower River Niger. Long-term monitoring programs are recommended to assess population trends, growth dynamics, and environmental influences, ensuring adaptive management strategies that promote the sustainability of these ecologically significant fish species.

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Sukhum, Kimberley V., Megan K. Freiler, Robert Wang, and Bruce A. Carlson. "The costs of a big brain: extreme encephalization results in higher energetic demand and reduced hypoxia tolerance in weakly electric African fishes." Proceedings of the Royal Society B: Biological Sciences 283, no. 1845 (2016): 20162157. http://dx.doi.org/10.1098/rspb.2016.2157.

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A large brain can offer several cognitive advantages. However, brain tissue has an especially high metabolic rate. Thus, evolving an enlarged brain requires either a decrease in other energetic requirements, or an increase in overall energy consumption. Previous studies have found conflicting evidence for these hypotheses, leaving the metabolic costs and constraints in the evolution of increased encephalization unclear. Mormyrid electric fishes have extreme encephalization comparable to that of primates. Here, we show that brain size varies widely among mormyrid species, and that there is little evidence for a trade-off with organ size, but instead a correlation between brain size and resting oxygen consumption rate. Additionally, we show that increased brain size correlates with decreased hypoxia tolerance. Our data thus provide a non-mammalian example of extreme encephalization that is accommodated by an increase in overall energy consumption. Previous studies have found energetic trade-offs with variation in brain size in taxa that have not experienced extreme encephalization comparable with that of primates and mormyrids. Therefore, we suggest that energetic trade-offs can only explain the evolution of moderate increases in brain size, and that the energetic requirements of extreme encephalization may necessitate increased overall energy investment.

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Xu-Friedman, M. A., and C. D. Hopkins. "Central mechanisms of temporal analysis in the knollenorgan pathway of mormyrid electric fish." Journal of Experimental Biology 202, no. 10 (1999): 1311–18. http://dx.doi.org/10.1242/jeb.202.10.1311.

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Mormyrid electric fish communicate using pulse-type electric organ discharges (EODs). The fine temporal structure of the waveforms of EODs varies widely throughout the 200 or more species of mormyrids. These signals carry information about the species, the sex and even the individual identity of the signaller. Behavioral experiments have shown that some species of fish are capable of using this information. Of the four known types of electroreceptors in mormyrid fish, the knollenorgan electroreceptor is the one most likely to be involved in the detection of conspecific EOD signals. Here, we review some recent advances in understanding how the central knollenorgan pathway might be analyzing the temporal structure of the EOD waveform. Fine temporal analysis appears to take place in the nucleus exterolateralis pars anterior (ELa), where tightly phase-locked inputs from the hindbrain drive a direct, excitatory input through a long axonal delay line and also drive an indirect, inhibitory input with negligible delay through the ELa large cell. These two inputs converge on ELa small cells, where they are hypothesized to interact in a ‘delay-line/blanking’ model. This initial temporal analysis is further refined in the nucleus exterolateralis pars posterior, where units tuned to ranges of pulse durations have been identified physiologically.

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Meek, J. "The cerebellum and timing: Lessons from mormyrids." Behavioral and Brain Sciences 20, no. 2 (1997): 258. http://dx.doi.org/10.1017/s0140525x9737143x.

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Mormyrid teleosts have Purkinje cells with palisade dendrites, which probably represent coincidence detectors of parallel fiber activity. Their existence strongly supports the ideas of Braitenberg et al. on cerebellar function. However, the organization of mormyrid granule cells and parallel fibers suggests that a key to cerebellar function is not in interactions within one wave, but between two opposite tidal waves.

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Bell, C. C., V. Z. Han, Y. Sugawara, and K. Grant. "Synaptic plasticity in the mormyrid electrosensory lobe." Journal of Experimental Biology 202, no. 10 (1999): 1339–47. http://dx.doi.org/10.1242/jeb.202.10.1339.

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The mormyrid electrosensory lateral line lobe (ELL) is one of several different sensory structures in fish that behave as adaptive sensory processors. These structures generate negative images of predictable features in the sensory inflow which are added to the actual inflow to minimize the effects of predictable sensory features. The negative images are generated through a process of association between centrally originating predictive signals and sensory inputs from the periphery. In vitro studies in the mormyrid ELL show that pairing of parallel fiber input with Na+ spikes in postsynaptic cells results in synaptic depression at the parallel fiber synapses. The synaptic plasticity observed at the cellular level and the associative process of generating negative images of predicted sensory input at the systems level share a number of properties. Both are rapidly established, anti-Hebbian, reversible, input-specific and tightly restricted in time. These common properties argue strongly that associative depression at the parallel fiber synapse contributes to the adaptive generation of negative images in the mormyrid ELL.

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Zhang, Yueping, and Victor Z. Han. "Physiology of Morphologically Identified Cells in the Posterior Caudal Lobe of the Mormyrid Cerebellum." Journal of Neurophysiology 98, no. 3 (2007): 1297–308. http://dx.doi.org/10.1152/jn.00502.2007.

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The cerebellum of the mormyrid fish consists of three major divisions: the valvula, the central lobes, and the caudal lobes. Several studies have focused on the central lobes and the valvula, but little is known about the caudal lobes. The mormyrid caudal lobe includes anterior and posterior components. The anterior caudal lobe is associated with the lateral line and eighth nerve end organs, whereas the posterior caudal lobe is associated with the electrosensory system. The present study examines the physiology and pharmacology of morphologically identified Purkinje cells and efferent cells in an in vitro slice preparation of the posterior caudal lobe. We found that the Purkinje cells in the posterior caudal lobe can be classified into three subtypes based on both their morphology and on their physiological responses to intracellular current injection and to synaptic inputs from parallel fibers and climbing fibers. Similarities and differences between the physiology of the caudal lobe and that of other regions of the mormyrid cerebellum and the mammalian cerebellum are discussed.

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Kramer, LB, FH van der Bank, and M. Wink. "Marcusenius desertus sp. nov. (Teleostei: Mormyridae), a mormyrid fish from the Namib desert." African Journal of Aquatic Science 41, no. 1 (2016): 1–18. http://dx.doi.org/10.2989/16085914.2015.1137855.

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Lavoué, Sébastien, Rémy Bigorne, Guillaume Lecointre, and Jean-François Agnèse. "Phylogenetic Relationships of Mormyrid Electric Fishes (Mormyridae; Teleostei) Inferred from Cytochrome b Sequences." Molecular Phylogenetics and Evolution 14, no. 1 (2000): 1–10. http://dx.doi.org/10.1006/mpev.1999.0687.

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Bell, C. C. "Sensory coding and corollary discharge effects in mormyrid electric fish." Journal of Experimental Biology 146, no. 1 (1989): 229–53. http://dx.doi.org/10.1242/jeb.146.1.229.

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Weakly electric fish use their electrosensory systems for electrocommunication, active electrolocation and low-frequency passive electrolocation. In electric fish of the family Mormyridae, these three purposes are mediated by separate classes of electroreceptors: electrocommunication by Knollenorgan electroreceptors, active electrolocation by Mormyromast electroreceptors and low-frequency passive electrolocation by ampullary electroreceptors. The primary afferent fibres from each class of electroreceptors terminate in a separate central region. Thus, the mormyrid electrosensory system has three anatomically and functionally distinct subsystems. This review describes the sensory coding and initial processing in each of the three subsystems, with an emphasis on the Knollenorgan and Mormyromast subsystems. The Knollenorgan subsystem is specialized for the measurement of temporal information but appears to ignore both intensity and spatial information. In contrast, the Mormyromast subsystem is specialized for the measurement of both intensity and spatial information. The morphological and physiological characteristics of the primary afferents and their central projection regions are quite different for the two subsystems and reflect the type of information which the subsystems preserve. This review also describes the electric organ corollary discharge (EOCD) effects which are present in the central projection regions of each of the three electrosensory subsystems. These EOCD effects are driven by the motor command that drives the electric organ to discharge. The EOCD effects are different in each of the three subsystems and these differences reflect differences in both the pattern and significance of the sensory information that is evoked by the fish's own electric organ discharge. Some of the EOCD effects are invariant, whereas others are plastic and depend on previous afferent input. The mormyrid work is placed within two general contexts: (a) the measurement of time and intensity in sensory systems, and (b) the various roles of motor command (efferent) signals and self-induced sensory (reafferent) signals in sensorimotor systems.

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Graff, Christian. "Firing Activity of the Weakly-Electric Fish Marcusenius Macrolepidotus (Mormyridae, Teleostei): Logarithmic Repartition of Inter-Pulse Intervals, and Sequential Inequality Testing." Behaviour 109, no. 3-4 (1989): 258–83. http://dx.doi.org/10.1163/156853989x00277.

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AbstractThe electric activity of mormyrid fish consists of short electric pulses, all identical, but separated by variable time intervals (inter-pulse interval or IPI). Temporal structures are here extracted from the sequence of IPIs, to show non-randomness in mormyrid electric signal. The electric activity of isolated Marcusenius macrolepidotus is comparable to that of other mormyrids. The pulse waveform is biphasic and symmetrical, it lasts 0.3 to 0.5 ms and its amplitude is about 13 volts. The pulses follow each other with extremely variable IPIs (14-500 ms) with large instantaneous variations. Two new methods of analysis have been developed here. The first is based on the fact that when IPIs are grouped in populations, longer IPI populations have a wider range than shorter ones, a lognormal rather than a normal distribution. The IPIs are therefore classified according not to absolute- but to relative differences: binwidths are in percent, not in milliseconds. The second, non-parametric method (sequential inequality testing), was first used for neurone firing activity. It considers the sign (+ or -) of the difference between successive IPIs, and compares the sequence of these signs with a theoretical random model. When M. macrolepidotus is resting, the sequence of longer and shorter IPIs is not random, as shown by redundancies of patterns of + and - signs. These redundancies and the IPI populations are typical for each individual. When the fish increases its locomotor activity (either spontaneously for a few seconds, or provoked over more than 20 s) the IPIs are shorter. The patterns of + and - are different when the fish is swimming and when resting. Behavioral and electrophysiological data suggest that receiving conspecifics may recognize these rhythm features. The analysis methods developed here may be useful to other stochastic phenomena, such as neural firing activity.

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Arnegard, Matthew E., and Bruce A. Carlson. "Electric organ discharge patterns during group hunting by a mormyrid fish." Proceedings of the Royal Society B: Biological Sciences 272, no. 1570 (2005): 1305–14. http://dx.doi.org/10.1098/rspb.2005.3101.

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Weakly electric fish emit and receive low-voltage electric organ discharges (EODs) for electrolocation and communication. Since the discovery of the electric sense, their behaviours in the wild have remained elusive owing to their nocturnal habits and the inaccessible environments in which they live. The transparency of Lake Malawi provided the first opportunity to simultaneously observe freely behaving mormyrid fish and record their EODs. We observed a piscivorous mormyrid, Mormyrops anguilloides , hunting in small groups in Lake Malawi while feeding on rock-frequenting cichlids of the largest known vertebrate species flock. Video recordings yielded the novel and unexpected finding that these groups resembled hunting packs by being largely composed of the same individuals across days. We show that EOD accelerations accompany prey probing and size estimation by M. anguilloides . In addition, group members occasionally synchronize bursts of EODs with an extraordinary degree of precision afforded by the mormyrid echo response. The characteristics and context of burst synchronization suggest that it may function as a pack cohesion signal. Our observations highlight the potential richness of social behaviours in a basal vertebrate lineage, and provide a framework for future investigations of the neural mechanisms, behavioural rules and ecological significance of social predation in M. anguilloides .

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Meek, J., K. Grant, and C. Bell. "Structural organization of the mormyrid electrosensory lateral line lobe." Journal of Experimental Biology 202, no. 10 (1999): 1291–300. http://dx.doi.org/10.1242/jeb.202.10.1291.

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The electrosensory lateral line lobe (ELL) of mormyrid teleosts is the first central stage in electrosensory input processing. It is a well-developed structure with six main layers, located in the roof of the rhombencephalon. Its main layers are, from superficial to deep, the molecular, ganglionic, plexiform, granular, intermediate and deep fiber layers. An important input arises from electroreceptors, but corollary electromotor command signals and proprioceptive, mechanosensory lateral line and descending electrosensory feedback inputs reach the ELL as well. The ELL input is processed by at least 14 cell types, which frequently show plastic responses to different inputs. The large ganglionic and large fusiform cells are the ELL projection cells. They are glutamatergic and project to the isthmic preeminential nucleus and the midbrain lateral toral nucleus. Interneurons are located in all ELL layers and are mostly GABAergic. The most remarkable interneurons are large multipolar cells in the intermediate layer, which have myelinated dendrites making presynaptic terminals contacting granular cells. With respect to the synaptic organization and microcircuitry of the ELL, a number of qualitative and quantitative aspects have been elucidated using electron microscopical and intracellular labeling techniques. However, the pathways by which primary afferent input influences the ELL projection cells are still undetermined: primary afferents do not seem to contact large fusiform or large ganglionic cells directly, but seem to terminate exclusively on granular cells, the axonal properties of which are not known. Consequently, more information of the structural organization of the ELL is still necessary for a detailed understanding of the neural basis of the plastic electrosensory input processing in mormyrids.

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Radmilovich, Milka, Isabel Barreiro, Leticia Iribarne, Kirsty Grant, Frank Kirschbaum, and María E. Castelló. "Post-hatching brain morphogenesis and cell proliferation in the pulse-type mormyrid Mormyrus rume proboscirostris." Journal of Physiology-Paris 110, no. 3 (2016): 245–58. http://dx.doi.org/10.1016/j.jphysparis.2016.11.007.

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Crawford, J. D., and X. Huang. "Communication signals and sound production mechanisms of mormyrid electric fish." Journal of Experimental Biology 202, no. 10 (1999): 1417–26. http://dx.doi.org/10.1242/jeb.202.10.1417.

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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.

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Mohr, Claudia, Patrick D. Roberts, and Curtis C. Bell. "The Mormyromast Region of the Mormyrid Electrosensory Lobe. I. Responses to Corollary Discharge and Electrosensory Stimuli." Journal of Neurophysiology 90, no. 2 (2003): 1193–210. http://dx.doi.org/10.1152/jn.00211.2003.

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This is the first of two papers on the electrosensory lobe (ELL) of mormyrid electric fish. The ELL is the first stage in the central processing of electrosensory information from electroreceptors. Cells of the mormyrid ELL are affected at the time of the electric organ discharge (EOD) by two different inputs, EOD-evoked reafferent input from electroreceptors and corollary discharge input associated with the motor command that elicits the EOD. This first paper examines the intracellular responses of ELL cells to these two different inputs in the region of ELL that receives primary afferent fibers from mormyromast electroreceptors. Mormyromast electroreceptors are responsible for active electrolocation. The paper extends previous studies of the mormyrid ELL by describing the physiological responses of cell types, which had been previously identified only morphologically, including: the two types of Purkinje-like medium ganglionic cells, MG1 and MG2; the thick smooth dendrite cells; and the medium fusiform cells. In addition, two previously unrecognized cell types, the large thick smooth dendrite cell and the interzonal cell, are described both morphologically and physiologically for the first time. Finally, new information is provided on the two types of ELL efferent cells, the large ganglionic and large fusiform cells. All cell types, except for the medium fusiform cell, show nonlinear interactions between electrosensory and corollary discharge inputs. All cell types, except for the medium fusiform cell and the interzonal cell, also show plasticity of the corollary discharge response after pairing with electrosensory stimuli.

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Nwani, C. D., E. E. OTI, G. E. Odoh, and H. M. G. Ezenwaji. "Endo-Parasitic Helminthes of Four Mormyrid Species (Osteichthyes: Mormyridae) from a West African Flood River System." Pakistan Journal of Biological Sciences 11, no. 2 (2008): 202–7. http://dx.doi.org/10.3923/pjbs.2008.202.207.

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25

Kvach, Yuriy, Miloslav Jirků, and Tomáš Scholz. "Acanthocephalans of the genus Megistacantha Golvan, 1960 (Palaeacanthocephala: Rhadinorhynchidae) in two African mormyrid fishes (Actinopterygii: Mormyridae)." Systematic Parasitology 93, no. 9 (2016): 927–33. http://dx.doi.org/10.1007/s11230-016-9672-6.

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26

Olopade, Olaniyi Alaba. "Preliminary Observations on the Family Mormyridae in Oyan Dam Lake (Nigeria)." Transylvanian Review of Systematical and Ecological Research 15, no. 1 (2013): 33–48. http://dx.doi.org/10.2478/trser-2013-0004.

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ABSTRACT This study was carried out to investigate the abundance, distribution, diversity and condition factor of Mormyrids in Oyan Dam lake, Abeokuta North Local Government Area of Ogun State, Nigeria. The fish were sampled from the catches of the fishermen in Oyan Dam lake, which used gillnets of 30-80 mm laterally stretched mesh size. The fish were sampled monthly between February and September 2011, at two different sites (Imala and Ibaro). The results revealed that a total number of 100 fishes of six species belonging to the family Mormyridae were collected. Numerically, catches were dominated by Mormyrus rume (34%), Hyperopisus bebe (30%) and Petrocephalus bane (24%). Together, these species comprised 88% of all collected individuals. Marcusenius ihuysi was rare and least in number representing 1% of the fish caught. The results showed that only four species were recorded in the dry season, namely Mormyrus rume, Hyperopisus bebe, Petrocephalus bane and Mormyrus deliciosus while five species were recorded in the wet season particularly in September. Mormyrus deliciosus, was not recorded in the wet season. In terms of body weight, the highest mean value was recorded for Mormyrus deliciosus (435.71 ± 95.71), followed by Mormyrus rume (143.82 ± 5.55) and Hyperopisus bebe (123.5 ± 5.26) while Petrocephalus bane was the least one (95.00 ± 8.56). The results also showed that the condition factor during the wet season (4.18) was higher than the condition factor of the dry season (3.51). Simpson’s index was used to determine the species richness, while Shannon-Wiener’s Index was used to evaluate species diversity; species evenness was equally evaluated using Pielou’s Index. The indices of diversity included (d) = 0.31 and 0.23, H = 1.18 and 1.53 and E = 0.851 and 0.853 respectively for the two sites at Oyan Dam lake. The estimates from these indices indicated a low fish species composition and richness, also unevenness in the population of Mormyrids in Oyan Dam lake. Therefore, it will be advisable to regulate the activities of fishers in the water body to allow future increase in the abundance of this species.

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27

Worm, Martin, Tim Landgraf, Julia Prume, Hai Nguyen, Frank Kirschbaum, and Gerhard von der Emde. "Evidence for mutual allocation of social attention through interactive signaling in a mormyrid weakly electric fish." Proceedings of the National Academy of Sciences 115, no. 26 (2018): 6852–57. http://dx.doi.org/10.1073/pnas.1801283115.

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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.

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Roberts, Patrick D. "Electrosensory response mechanisms in mormyrid electric fish." Neurocomputing 32-33 (June 2000): 243–48. http://dx.doi.org/10.1016/s0925-2312(00)00170-3.

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29

Moller, Peter, and Jacques Serrier. "Species recognition in mormyrid weakly electric fish." Animal Behaviour 34, no. 2 (1986): 333–39. http://dx.doi.org/10.1016/s0003-3472(86)80101-4.

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30

Carlson, Bruce A. "Neuroanatomy of the mormyrid electromotor control system." Journal of Comparative Neurology 454, no. 4 (2002): 440–55. http://dx.doi.org/10.1002/cne.10462.

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31

Meek, Johannes, Theo G. M. Hafmans, Victor Han, Curtis C. Bell, and Kirsty Grant. "Myelinated dendrites in the mormyrid electrosensory lobe." Journal of Comparative Neurology 431, no. 3 (2001): 255–75. http://dx.doi.org/10.1002/1096-9861(20010312)431:3<255::aid-cne1069>3.0.co;2-9.

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32

Zhang, Yueping, Gerhard Magnus, and Victor Z. Han. "Cell type-specific plasticity at parallel fiber synapses onto Purkinje cells in the posterior caudal lobe of the mormyrid fish cerebellum." Journal of Neurophysiology 120, no. 2 (2018): 644–61. http://dx.doi.org/10.1152/jn.00175.2018.

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It has been demonstrated that there are two morphological subtypes of Purkinje cells (PCs)—fan-shaped Purkinje cells (fPCs) and multipolar Purkinje cells (mPCs)—in the posterior caudal lobe of the mormyrid fish cerebellum, but whether these cell types are also functionally distinct is unknown. Here, we have used electrophysiological and pharmacological tools in a slice preparation to demonstrate that pairing parallel fiber (PF) and climbing fiber (CF) inputs at a low frequency induces long-term depression (LTD) in fPCs but long-term potentiation (LTP) in mPCs. The induction of plasticity in both cell types required postsynaptic Ca2+ and type 1α metabotropic glutamate receptors. However, the LTD in fPCs was inducted via a calcium/calmodulin-dependent protein kinase II cascade, whereas LTP induction in mPCs required calcineurin. Moreover, the LTD in fPCs and LTP in mPCs were accompanied by changes to the corresponding paired-pulse ratios and their coefficients of variation, suggesting presynaptic modes of expression for the plasticity at PF terminals for both cell types. Hence, the synaptic plasticity at PF synapses onto PCs in the posterior caudal lobe of the mormyrid cerebellum is cell type specific, with both pre- and postsynaptic mechanisms contributing to its induction and expression. NEW & NOTEWORTHY Much has been learnt about the cerebellar long-term depression (LTD) in the cortex. More recent work has shown that long-term potentiation (LTP) is equally important for cerebellar motor learning. Here we report for the first time that plasticity in the mormyrid cerebellum is cell type specific, e.g., following the conventional pairing of parallel and climbing fiber inputs in an in vitro preparation leads to LTD in one Purkinje cell subtype and LTP in another.

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33

Terleph, T. A. "Effects of social interaction on the electric organ discharge in a mormyrid fish, Gnathonemus petersii (Mormyridae, Teleostei)." Journal of Experimental Biology 206, no. 14 (2003): 2355–62. http://dx.doi.org/10.1242/jeb.00437.

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34

Bell, C., K. Dunn, C. Hall, and A. Caputi. "Electric organ corollary discharge pathways in mormyrid fish." Journal of Comparative Physiology A 177, no. 4 (1995): 449–62. http://dx.doi.org/10.1007/bf00187481.

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35

Bell, C., and G. von der Emde. "Electric organ corollary discharge pathways in mormyrid fish." Journal of Comparative Physiology A 177, no. 4 (1995): 463–79. http://dx.doi.org/10.1007/bf00187482.

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36

Crawford, John D. "Hearing and acoustic communication in mormyrid electric fishes." Marine and Freshwater Behaviour and Physiology 29, no. 1-4 (1997): 65–86. http://dx.doi.org/10.1080/10236249709379001.

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37

von der Emde, G. "Active electrolocation of objects in weakly electric fish." Journal of Experimental Biology 202, no. 10 (1999): 1205–15. http://dx.doi.org/10.1242/jeb.202.10.1205.

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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.

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38

Sullivan, J. P., S. Lavoue, and C. D. Hopkins. "Molecular systematics of the african electric fishes (Mormyroidea: teleostei) and a model for the evolution of their electric organs." Journal of Experimental Biology 203, no. 4 (2000): 665–83. http://dx.doi.org/10.1242/jeb.203.4.665.

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We present a new molecular phylogeny for 41 species of African mormyroid electric fishes derived from the 12S, 16S and cytochrome b genes and the nuclear RAG2 gene. From this, we reconstruct the evolution of the complex electric organs of these fishes. Phylogenetic results are generally concordant with earlier preliminary molecular studies of a smaller group of species and with the osteology-based classification of Taverne, which divides the group into the Gymnarchidae and the Mormyridae, with the latter including the subfamilies Petrocephalinae (Petrocephalus) and Mormyrinae (all remaining taxa). However, we find that several genera previously recognized by Taverne are non-monophyletic. Within the Mormyrinae, the genus Myomyrus is the sister group to all the remaining taxa. Other well-supported clades within this group are recovered. A reconstruction of electrocyte evolution on the basis of our best-supported topology suggests that electrocytes with penetrating stalks evolved once early in the history of the mormyrids followed by multiple paedomorphic reversals to electrocytes with non-penetrating stalks.

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von der Emde, Gerhard, Leonel Gómez Sena, Rafaella Niso, and Kirsty Grant. "The Midbrain Precommand Nucleus of the Mormyrid Electromotor Network." Journal of Neuroscience 20, no. 14 (2000): 5483–95. http://dx.doi.org/10.1523/jneurosci.20-14-05483.2000.

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40

Prechtl, James C., Gerhard von der Emde, Jakob Wolfart, et al. "Sensory Processing in the Pallium of a Mormyrid Fish." Journal of Neuroscience 18, no. 18 (1998): 7381–93. http://dx.doi.org/10.1523/jneurosci.18-18-07381.1998.

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41

Baron, V. D., A. S. Golubtsov, and A. A. Orlov. "Phase locking and phase avoidance behavior in eleven Nilotic mormyrid species (Mormyridae, Mormyriformes) in response to external electric stimuli." Journal of Ichthyology 57, no. 4 (2017): 617–24. http://dx.doi.org/10.1134/s0032945217040014.

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42

Schugardt, Christian, and Frank Kirschbaum. "Control of Gonadal Maturation and Regression by Experimental Variation of Environmental Factors in the Mormyrid Fish, Mormyrus rume proboscirostris." Environmental Biology of Fishes 70, no. 3 (2004): 227–33. http://dx.doi.org/10.1023/b:ebfi.0000033340.49266.f3.

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43

Kunze, Peter, and Hans-Ulrich Wezstein. "Apomorphine and haloperidol influence electric behaviour of a mormyrid fish." Zeitschrift für Naturforschung C 43, no. 1-2 (1988): 105–7. http://dx.doi.org/10.1515/znc-1988-1-220.

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The electric behaviour of the mormyrid Gnathonemus petersii is changed by dopaminergic drugs applied to the aquarium water. The upper limit of the interpuis interval distributions is significantly shifted to shorter intervals by apomorphine-HCl (.082-,328 mg/ml), and to longer intervals by haloperidol (.041 -.164 mg/ml). The effect of apomorphine is antagonized by haloperidol. Probably, a dopamin system is involved in the neural control of the electric organ

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44

Sukhum, Kimberley V., Megan K. Freiler, and Bruce A. Carlson. "Intraspecific Energetic Trade-Offs and Costs of Encephalization Vary from Interspecific Relationships in Three Species of Mormyrid Electric Fishes." Brain, Behavior and Evolution 93, no. 4 (2019): 196–205. http://dx.doi.org/10.1159/000501233.

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The evolution of increased encephalization comes with an energetic cost. Across species, this cost may be paid for by an increase in metabolic rate or by energetic trade-offs between the brain and other energy-expensive tissues. However, it remains unclear whether these solutions to deal with the energetic requirements of an enlarged brain are related to direct physiological constraints or other evolved co-adaptations. We studied the highly encephalized mormyrid fishes, which have extensive species diversity in relative brain size. We previously found a correlation between resting metabolic rate and relative brain size across species; however, it is unknown how this interspecific relationship evolved. To address this issue, we measured intraspecific variation in relative brain size, the sizes of other organs, metabolic rate, and hypoxia tolerance to determine if intraspecific relationships between brain size and organismal energetics are similar to interspecific relationships. We found that 3 species of mormyrids with varying degrees of encephalization had no intraspecific relationships between relative brain size and relative metabolic rate or relative sizes of other organs, and only 1 species had a relationship between relative brain size and hypoxia tolerance. These species-specific differences suggest that the interspecific relationship between metabolic rate and relative brain size is not the result of direct physiological constraints or strong stabilizing selection, but is instead due to other species level co-adaptations. We conclude that variation within species must be considered when determining the energetic costs and trade-offs underlying the evolution of extreme encephalization.

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Baker, C. A., T. Kohashi, A. M. Lyons-Warren, X. Ma, and B. A. Carlson. "Multiplexed temporal coding of electric communication signals in mormyrid fishes." Journal of Experimental Biology 216, no. 13 (2013): 2365–79. http://dx.doi.org/10.1242/jeb.082289.

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46

Engelmann, J., E. van den Burg, J. Bacelo, et al. "Dendritic backpropagation and synaptic plasticity in the mormyrid electrosensory lobe." Journal of Physiology-Paris 102, no. 4-6 (2008): 233–45. http://dx.doi.org/10.1016/j.jphysparis.2008.10.004.

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Kirschbaum, Frank, and Christian Schugardt. "Reproductive strategies and developmental aspects in mormyrid and gymnotiform fishes." Journal of Physiology-Paris 96, no. 5-6 (2002): 557–66. http://dx.doi.org/10.1016/s0928-4257(03)00011-1.

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48

Somiya, Hiroaki. "Guanine-Type retinal tapetum of three species of mormyrid fishes." Japanese Journal of Ichthyology 36, no. 2 (1989): 220–26. http://dx.doi.org/10.1007/bf02914325.

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49

Noe, Angela, and Peter Kunze. "HPLC-Determination of Apomorphine in a Mormyrid Fish, Gnathonemus petersii." Zeitschrift für Naturforschung C 44, no. 11-12 (1989): 917–19. http://dx.doi.org/10.1515/znc-1989-11-1207.

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Abstract Uptake of apomorphine and elimination kinetics in brain and muscle tissue of the weakly electric fish Gnathonemus petersii (Mormyridae) was determined by HPLC. 20 min exposure of the fish to apomorphine in the aquarium water (0.4 mg/1) resulted in a concentration factor of 1.09 for brain and 0.55 for muscle tissue. Elimination from brain tissue can be described with first order kinetics (t1/2 = 2.4 h).

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50

Wullimann, Mario F., and Donal J. Rooney. "A direct cerebello-telencephalic projection in an electrosensory mormyrid fish." Brain Research 520, no. 1-2 (1990): 354–57. http://dx.doi.org/10.1016/0006-8993(90)91730-5.

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