The third form electric organ discharge of electric eels

AbstractThe electric eel is a unique species that has evolved three electric organs. Since the 1950s, electric eels have generally been assumed to use these three organs to generate two forms of electric organ discharge (EOD): high-voltage EOD for predation and defense and low-voltage EOD for electrolocation and communication. However, why electric eels evolved three electric organs to generate two forms of EOD and how these three organs work together to generate these two forms of EOD have not been clear until now. Here, we present the third form of independent EOD of electric eels: middle-voltage EOD. We suggest that every form of EOD is generated by one electric organ independently and reveal the typical discharge order of the three electric organs. We also discuss hybrid EODs, which are combinations of these three independent EODs. This new finding indicates that the electric eel discharge behavior and physiology and the evolutionary purpose of the three electric organs are more complex than previously assumed. The purpose of the middle-voltage EOD still requires clarification.

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Operation Modes of HV/MV Substations

Scientific Journal of Riga Technical University Power and Electrical Engineering ◽

10.2478/v10144-009-0018-y ◽

2009 ◽

Vol 25 (25) ◽

pp. 81-86

Author(s):

Josifs Survilo ◽

Antons Kutjuns

Keyword(s):

High Voltage ◽

Low Voltage ◽

Warm Season ◽

Electrical Energy ◽

Cold Season ◽

Power Losses ◽

Medium Voltage ◽

The Third ◽

Operation Modes ◽

Mode 3

Operation Modes of HV/MV SubstationsA distribution network consists of high voltage grid, medium voltage grid, and low voltage grid. Medium voltage grid is connected to high voltage grid via substations with HV/MV transformers. The substation may contain one, mostly two but sometimes even more transformers. Out of reliability and expenditure considerations the two transformer option prevail over others mentioned. For two transformer substation, there may be made choice out of several operation modes: 1) two (small) transformers, with rated power each over 0.7 of maximum substation load, permanently in operation; 2) one (big) transformer, with rated power over maximum substation load, permanently in operation and small transformer in constant cold reserve; 3) big transformer in operation in cold season, small transformer-in warm one. Considering transformer load losses and no load losses and observing transformer loading factor β it can be said that the mode 1) is less advantageous. The least power losses has the mode 3). There may be singled out yet three extra modes of two transformer substations: 4) two big transformers in permanent operation; 5) one big transformer permanently in operation and one such transformer in cold reserve; 6) two small transformers in operation in cold season of the year, in warm season-one small transformer on duty. At present mostly two transformers of equal power each are installed on substations and in operation is one of them, hence extra mode 5). When one transformer becomes faulty, it can be changed for smaller one and the third operation mode can be practiced. Extra mode 4) is unpractical in all aspects. The mode 6) has greater losses than the mode 3) and is not considered in detail. To prove the advantage of the third mode in sense of power losses, the notion of effective utilization time of power losses was introduced and it was proven that relative value of this quantity diminishes with loading factor β. The use of advantageous substation option would make it possible to save notable amount of electrical energy but smaller transformer lifetime of this option must be taken into account as well.

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Electric organ discharge patterns during group hunting by a mormyrid fish

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2005.3101 ◽

2005 ◽

Vol 272 (1570) ◽

pp. 1305-1314 ◽

Cited By ~ 58

Author(s):

Matthew E Arnegard ◽

Bruce A Carlson

Keyword(s):

Low Voltage ◽

Electric Organ Discharge ◽

Electric Organ ◽

Lake Malawi ◽

Weakly Electric Fish ◽

Species Flock ◽

Unexpected Finding ◽

Size Estimation ◽

Vertebrate Lineage ◽

Mormyrid Fish

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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Electric organ discharge (EOD) and prey capture behaviour in the electric eel, Electrophorus electricus

Behavioral Ecology and Sociobiology ◽

10.1007/bf00303239 ◽

1979 ◽

Vol 4 (4) ◽

pp. 311-319 ◽

Cited By ~ 16

Author(s):

R. Bauer

Keyword(s):

Prey Capture ◽

Electric Organ Discharge ◽

Electric Organ ◽

Electrophorus Electricus ◽

Electric Eel

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Species differences in electric organs of mormyrids: Substrates for species-typical electric organ discharge waveforms

The Journal of Comparative Neurology ◽

10.1002/cne.902440305 ◽

1986 ◽

Vol 244 (3) ◽

pp. 313-330 ◽

Cited By ~ 44

Author(s):

Andrew H. Bass

Keyword(s):

Species Differences ◽

Electric Organ Discharge ◽

Electric Organ ◽

Electric Organs

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The diet of the coffin ray, Hypnos monopterygius (Shaw, 1795), and predation mode inferred from jaw, dentition and electric organ morphology

Marine and Freshwater Research ◽

10.1071/mf16200 ◽

2017 ◽

Vol 68 (6) ◽

pp. 1193 ◽

Cited By ~ 1

Author(s):

A.-M. Frost ◽

I. P. Jacobsen ◽

M. B. Bennett

Keyword(s):

Body Mass ◽

Electric Organ Discharge ◽

Electric Organ ◽

Stomach Contents ◽

Organ Size ◽

Teleost Fishes ◽

Marked Contrast ◽

Organ Mass ◽

Electric Organs ◽

Stomach Contents Analysis

The diet of the coffin ray, Hypnos monopterygius (Family Hypnidae), an electric ray endemic to Australia, was described on the basis of stomach contents analysis. Benthos-associated teleost fishes and cephalopod molluscs, predominantly Octopus, dominated the diet. The large, paired electric organs of this species scaled close to isometrically in relation to body mass for electric-organ area and electric-organ mass. The number of electrocyte columns that comprise each electric organ (mean=435 columns) was independent of body mass. Jaws were long and slender, and supported small tricuspidate teeth only on the central 55% of their length. Diet, electric-organ size and jaw morphology in Hypnos and the torpedoes (Family Torpedinidae) are similar, but in marked contrast to members of the numbfishes (Family Narcinidae). The differences are interpreted in relation to the use of electric-organ discharge while foraging in the former families.

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