The Mormyridae, sometimes called "elephantfish" (more properly freshwater elephantfish), are a superfamily of weakly electric fish in the order Osteoglossiformes native to Africa.[1] It is by far the largest family in the order, with around 200 species. Members of the family can be popular, if challenging, aquarium species. These fish have a large brain size and unusually high intelligence.
The elephantfish are a diverse family, with a wide range of different sizes and shapes. The smallest are just 5 cm (2.0 in) in adult length, while the largest reach up to 1.5 m (4.9 ft). They do, however, have a number of unique features in common. Firstly, their cerebellum is greatly enlarged, enabling them to interpret complex bio-electrical signals,[2] and to the large size of the valve.[3][4] Secondly, an auditory vesicle (a small bladder) is present inside the labyrinth of the left and right inner ears. This vesicle, together with a bag with an otolith (sacculum containing the otolith sagitta), itself communicating to the lagena (containing the otolith asteriscus), is in fact unique among vertebrates, completely independent of the other organs; it is neither connected to the labyrinth to which only one otolith bag (the utriculus containing the otolith lapillus) is attached, nor is it connected to the swim bladder (except in embryos) of which it has the same histological structure, nor is it therefore related to the pharynx.[5]
Some species possess modifications of their mouthparts to facilitate electrolocating and feeding on small invertebrates buried in muddy substrates. The shape and structure of these leads to the popular name "elephant-nosed fish" for those species with particularly prominent mouth extensions. The extensions to the mouthparts usually consist of a fleshy elongation attached to the lower jaw. They are flexible, and equipped with touch, and possibly taste, sensors. The mouth is not protrusible, and the head (including the eyes), the dorsum, and belly are covered by a thin layer of skin that is perforated with small pores leading to electroreceptors.[citation needed]
The retina is called a "grouped retina", an eye structure seen in mormyrids and a few other fishes.[6] Instead of being smooth, their retina is composed of tiny cups, acting like parabolic mirrors. Because of the murky waters they inhabit, the cones in their eyes have adapted to see only red light. The cups are made of four layers of light-reflecting proteins, funneling red light to areas of cones, intensifying its brightness 10-fold, while the rods are hit by light from other wavelengths.[7] Only a single gonad is present, located on the left side of their body.[8] The Mormyridae and the closely related genus Gymnarchus are also unique in being the only vertebrates where the male sperm cell does not have a flagellum.[9]
Electric fieldsEdit
Mormyromast, a type of electroreceptor found only in mormyrid fishes
Elephantfish possess electric organs that generate weak electric fields, and electroreceptors (ampullae of Lorenzini, knollenorgans, and Mormyromasts) that detect small variations in these electric fields caused by the presence of prey or other objects of different conductivities. This allows them to sense their environment in turbid waters where vision is impaired by suspended matter.[10][11]
Electric fish can be classified into two types: pulse fish or wave fish. Pulse-type discharges are characterized by long intervals between electric discharges, whereas wave-type discharges occur when the interval between consecutive pulses is so brief that the discharges fuse together to form a wave.[12] The electric discharge is produced from an electric organ that evolved from muscle, as can also be seen in gymnotiform electric fish, electric rays, and skates. The convergent evolution between the South American gymnotiforms and the African Mormyridae is remarkable, with the electric organ being produced by the substitution of the same amino acid in the same voltage-gated sodium channel despite the two groups of fish being on different continents and the evolution of the electric sense organ being separated in time by around 60 million years.[13] Convergent changes to other key transcription factors and regulatory pathways in both Gymnotiforms and Mormyridae also contributed to the evolution of the electric sense organ.[14]
Bronze figurine of Oxyrhynchus fish, Late Period-Ptolemaic Egypt
The Medjed was a sacred fish in Ancient Egypt. At the city of Per-Medjed, better known as Oxyrhynchus, whose name means "sharp-nosed" after the fish, archaeologists have found fishes depicted as bronze figurines, mural paintings, or wooden coffins in the shape of fishes with downturned snouts, with horned sun-disc crowns like those of the goddess Hathor. The depictions have been described as resembling members of the genus Mormyrus.[18]
ReferencesEdit
^Froese, Rainer, and Daniel Pauly, eds. (2017). "Mormyridae" in FishBase. April 2017 version.
^Chapman, Lauren J.; Hulen, Kevin G. (2001). "Implications of hypoxia for the brain size and gill morphometry of mormyrid fishes". Journal of Zoology. 254 (4): 461–472. doi:10.1017/S0952836901000966.
^Glickstein, M.; Voogd, J. (2009). "Cerebellum: Evolution and Comparative Anatomy". Encyclopedia of Neuroscience: 743–756. doi:10.1016/B978-008045046-9.00947-5. ISBN978-0-08-045046-9.
^Wullimann, Mario F.; Rooney, Donal J. (1990). "A direct cerebello-telencephalic projection in an electrosensory mormyrid fish" (PDF). Brain Research. 520 (1–2): 354–357. doi:10.1016/0006-8993(90)91730-5. PMID 1698507. S2CID 12951395.
^Orts, S. (1967): Contribution to the comparative anatomy and systematics of Mormyroïdes (RAOS Prize 1966) - Ann. Acad. Roy. Sc. d'Outre Mer, Classe des Sc. Nat. et Méd., Bruxelles, XVII, 3, 1-89, 30 figs, 3 tabs, 8 pls, 1967 (in French)
^Francke, Mike; Kreysing, Moritz; Mack, Andreas; et al. (2014). "Grouped retinae and tapetal cups in some Teleostian fish: Occurrence, structure, and function". Progress in Retinal and Eye Research. 38: 43–69. doi:10.1016/j.preteyeres.2013.10.001. PMID 24157316. S2CID 39081714.
^The generation of these electric fields and their use in providing the fish with additional sensory input from the environment is the subject of considerable scientific research, as is research into communication between and within species
^Caputi, A. A. (1999). "The electric organ discharge of pulse gymnotiforms: the transformation of a simple impulse into a complex spatiotemporal electromotor pattern". Journal of Experimental Biology. 202 (# (Pt 10)): 1229–1241. doi:10.1242/jeb.202.10.1229. PMID 10210664.
^Arnegard, M. E.; Zwickl, D. J.; Lu, Y.; Zakon, H. H. (2010-12-02). "Old gene duplication facilitates origin and diversification of an innovative communication system--twice". Proceedings of the National Academy of Sciences. 107 (51): 22172–22177. doi:10.1073/pnas.1011803107. PMC3009798. PMID 21127261.
^Gallant, Jason R.; Traeger, Lindsay L.; Volkening, Jeremy D.; Moffett, Howell; Chen, Po-Hao; Novina, Carl D.; Phillips, George N.; Anand, Rene; Wells, Gregg B.; Pinch, Matthew; Güth, Robert (2014-06-27). "Genomic basis for the convergent evolution of electric organs". Science. 344 (6191): 1522–1525. Bibcode:2014Sci...344.1522G. doi:10.1126/science.1254432. PMC5541775. PMID 24970089.
^Lavoué, S.; Sullivan, J. P.; Hopkins, C. D. (2003). "Phylogenetic utility of the first two introns of the S7 ribosomal protein gene in African electric fishes (Mormyroidea: Teleostei) and congruence with other molecular markers". Biological Journal of the Linnean Society. 78 (2): 273–292. doi:10.1046/j.1095-8312.2003.00170.x.
^Sullivan, J. P.; Lavoué, S.; Hopkins, C. D. (2000). "Molecular systematics of the African electric fishes (Mormyroidea: Teleostei) and a model for the evolution of their electric organs". Journal of Experimental Biology. 203 (Pt 4): 665–683. doi:10.1242/jeb.203.4.665. PMID 10648209.
^Sullivan, J. P.; Lavoué, S.; Hopkins, C. D. (2016). "Cryptomyrus: a new genus of Mormyridae (Teleostei, Osteoglossomorpha) with two new species from Gabon, West-Central Africa". ZooKeys (561): 117–150. doi:10.3897/zookeys.561.7137. PMC4768369. PMID 27006619.
^Van Neer, Wim; Gonzalez, Jérôme (2019). "A Late Period fish deposit at Oxyrhynchus (el-Bahnasa, Egypt)". In Peters, Joris; McGlynn, George; Goebel, Veronika (eds.). Documenta Archaeobiologiae Animals: Cultural Identifiers In Ancient Societies?(PDF). Rahden, Westfalia, Germany: Verlag Marie Leidorf. ISBN978-3-89646-674-7.
External linksEdit
Media related to Mormyridae at Wikimedia Commons
Data related to Mormyridae at Wikispecies
Detailed research paper on the sensory and central nervous systems in Gnathonemus petersi
Mormyrids in the aquarium
Mormyridae - African weakly electric fishes (including interactive checklist)
October 20, 2023
mormyridae, sometimes, called, elephantfish, more, properly, freshwater, elephantfish, superfamily, weakly, electric, fish, order, osteoglossiformes, native, africa, largest, family, order, with, around, species, members, family, popular, challenging, aquarium. The Mormyridae sometimes called elephantfish more properly freshwater elephantfish are a superfamily of weakly electric fish in the order Osteoglossiformes native to Africa 1 It is by far the largest family in the order with around 200 species Members of the family can be popular if challenging aquarium species These fish have a large brain size and unusually high intelligence Freshwater elephantfishGnathonemus petersiiScientific classificationDomain EukaryotaKingdom AnimaliaPhylum ChordataClass ActinopterygiiOrder OsteoglossiformesFamily MormyridaeSubfamiliesMormyrinaePetrocephalinaeThey are not to be confused with the marine and brackish water callorhinchid elephantfish family Callorhinchidae of Southern Hemisphere oceans Contents 1 Description and biology 1 1 Electric fields 2 Classification 3 In culture 4 References 5 External linksDescription and biology EditThe elephantfish are a diverse family with a wide range of different sizes and shapes The smallest are just 5 cm 2 0 in in adult length while the largest reach up to 1 5 m 4 9 ft They do however have a number of unique features in common Firstly their cerebellum is greatly enlarged enabling them to interpret complex bio electrical signals 2 and to the large size of the valve 3 4 Secondly an auditory vesicle a small bladder is present inside the labyrinth of the left and right inner ears This vesicle together with a bag with an otolith sacculum containing the otolith sagitta itself communicating to the lagena containing the otolith asteriscus is in fact unique among vertebrates completely independent of the other organs it is neither connected to the labyrinth to which only one otolith bag the utriculus containing the otolith lapillus is attached nor is it connected to the swim bladder except in embryos of which it has the same histological structure nor is it therefore related to the pharynx 5 Some species possess modifications of their mouthparts to facilitate electrolocating and feeding on small invertebrates buried in muddy substrates The shape and structure of these leads to the popular name elephant nosed fish for those species with particularly prominent mouth extensions The extensions to the mouthparts usually consist of a fleshy elongation attached to the lower jaw They are flexible and equipped with touch and possibly taste sensors The mouth is not protrusible and the head including the eyes the dorsum and belly are covered by a thin layer of skin that is perforated with small pores leading to electroreceptors citation needed The retina is called a grouped retina an eye structure seen in mormyrids and a few other fishes 6 Instead of being smooth their retina is composed of tiny cups acting like parabolic mirrors Because of the murky waters they inhabit the cones in their eyes have adapted to see only red light The cups are made of four layers of light reflecting proteins funneling red light to areas of cones intensifying its brightness 10 fold while the rods are hit by light from other wavelengths 7 Only a single gonad is present located on the left side of their body 8 The Mormyridae and the closely related genus Gymnarchus are also unique in being the only vertebrates where the male sperm cell does not have a flagellum 9 Electric fields Edit nbsp Mormyromast a type of electroreceptor found only in mormyrid fishesFurther information Electroreception and electrogenesis Elephantfish possess electric organs that generate weak electric fields and electroreceptors ampullae of Lorenzini knollenorgans and Mormyromasts that detect small variations in these electric fields caused by the presence of prey or other objects of different conductivities This allows them to sense their environment in turbid waters where vision is impaired by suspended matter 10 11 Electric fish can be classified into two types pulse fish or wave fish Pulse type discharges are characterized by long intervals between electric discharges whereas wave type discharges occur when the interval between consecutive pulses is so brief that the discharges fuse together to form a wave 12 The electric discharge is produced from an electric organ that evolved from muscle as can also be seen in gymnotiform electric fish electric rays and skates The convergent evolution between the South American gymnotiforms and the African Mormyridae is remarkable with the electric organ being produced by the substitution of the same amino acid in the same voltage gated sodium channel despite the two groups of fish being on different continents and the evolution of the electric sense organ being separated in time by around 60 million years 13 Convergent changes to other key transcription factors and regulatory pathways in both Gymnotiforms and Mormyridae also contributed to the evolution of the electric sense organ 14 Classification EditMain article Mormyridae superfamily Classification The roughly 221 species of elephantfish are grouped into two subfamilies the Mormyrinae and Petrocephalinae The latter has only a single genus Phylogeny 15 16 Mormyridae Petrocephalinae PetrocephalusMormyrinae MyomyrusMormyropsBrienomyrusIsichthysMormyrusPollimyrusStomatorhinusParamormyropsCryptomyrusBoulengeromyrusIvindomyrusHyperopisusBrevimyrusHippopotamyrusCampylomormyrusGnathonemusGenyomyrusMarcuseniusFamily Mormyridae Subfamily Mormyrinae Boulengeromyrus Taverne amp Gery 1968 Brevimyrus Taverne 1971 Brienomyrus Taverne 1971 Campylomormyrus Bleeker 1874 Cryptomyrus J P Sullivan Lavoue amp C D Hopkins 2016 17 Cyphomyrus Pappenheim 1906 Genyomyrus Boulenger 1898 Gnathonemus Gill 1863 Heteromormyrus Steindachner 1866 Hippopotamyrus Pappenheim 1906 Hyperopisus Gill 1862 Isichthys Gill 1863 Ivindomyrus Taverne amp Gery 1975 Marcusenius Gill 1862 Mormyrops J P Muller 1843 Mormyrus Linnaeus 1758 Myomyrus Boulenger 1898 Oxymormyrus Bleeker 1874 Paramormyrops Taverne Thys van den Audenaerde amp Heymer 1977 Pollimyrus Taverne 1971 Stomatorhinus Boulenger 1898 Subfamily Petrocephalinae Petrocephalus Marcusen 1854In culture Edit nbsp Bronze figurine of Oxyrhynchus fish Late Period Ptolemaic EgyptThe Medjed was a sacred fish in Ancient Egypt At the city of Per Medjed better known as Oxyrhynchus whose name means sharp nosed after the fish archaeologists have found fishes depicted as bronze figurines mural paintings or wooden coffins in the shape of fishes with downturned snouts with horned sun disc crowns like those of the goddess Hathor The depictions have been described as resembling members of the genus Mormyrus 18 References Edit Froese Rainer and Daniel Pauly eds 2017 Mormyridae in FishBase April 2017 version Chapman Lauren J Hulen Kevin G 2001 Implications of hypoxia for the brain size and gill morphometry of mormyrid fishes Journal of Zoology 254 4 461 472 doi 10 1017 S0952836901000966 Glickstein M Voogd J 2009 Cerebellum Evolution and Comparative Anatomy Encyclopedia of Neuroscience 743 756 doi 10 1016 B978 008045046 9 00947 5 ISBN 978 0 08 045046 9 Wullimann Mario F Rooney Donal J 1990 A direct cerebello telencephalic projection in an electrosensory mormyrid fish PDF Brain Research 520 1 2 354 357 doi 10 1016 0006 8993 90 91730 5 PMID 1698507 S2CID 12951395 Orts S 1967 Contribution to the comparative anatomy and systematics of Mormyroides RAOS Prize 1966 Ann Acad Roy Sc d Outre Mer Classe des Sc Nat et Med Bruxelles XVII 3 1 89 30 figs 3 tabs 8 pls 1967 in French Francke Mike Kreysing Moritz Mack Andreas et al 2014 Grouped retinae and tapetal cups in some Teleostian fish Occurrence structure and function Progress in Retinal and Eye Research 38 43 69 doi 10 1016 j preteyeres 2013 10 001 PMID 24157316 S2CID 39081714 Elephant Nosed Fish Has Funky Eyes Too Communication Behavior and Sensory Mechanisms in Weakly Electric Fishes Miller S Sullivan J Mormyridae Bonaparte 1831 Mormyridae African weakly electric fishes Retrieved 20 October 2023 Bustami H P 2007 Smart elephant fish navigates in darkness with electric fields life of science net The generation of these electric fields and their use in providing the fish with additional sensory input from the environment is the subject of considerable scientific research as is research into communication between and within species Caputi A A 1999 The electric organ discharge of pulse gymnotiforms the transformation of a simple impulse into a complex spatiotemporal electromotor pattern Journal of Experimental Biology 202 Pt 10 1229 1241 doi 10 1242 jeb 202 10 1229 PMID 10210664 Arnegard M E Zwickl D J Lu Y Zakon H H 2010 12 02 Old gene duplication facilitates origin and diversification of an innovative communication system twice Proceedings of the National Academy of Sciences 107 51 22172 22177 doi 10 1073 pnas 1011803107 PMC 3009798 PMID 21127261 Gallant Jason R Traeger Lindsay L Volkening Jeremy D Moffett Howell Chen Po Hao Novina Carl D Phillips George N Anand Rene Wells Gregg B Pinch Matthew Guth Robert 2014 06 27 Genomic basis for the convergent evolution of electric organs Science 344 6191 1522 1525 Bibcode 2014Sci 344 1522G doi 10 1126 science 1254432 PMC 5541775 PMID 24970089 Lavoue S Sullivan J P Hopkins C D 2003 Phylogenetic utility of the first two introns of the S7 ribosomal protein gene in African electric fishes Mormyroidea Teleostei and congruence with other molecular markers Biological Journal of the Linnean Society 78 2 273 292 doi 10 1046 j 1095 8312 2003 00170 x Sullivan J P Lavoue S Hopkins C D 2000 Molecular systematics of the African electric fishes Mormyroidea Teleostei and a model for the evolution of their electric organs Journal of Experimental Biology 203 Pt 4 665 683 doi 10 1242 jeb 203 4 665 PMID 10648209 Sullivan J P Lavoue S Hopkins C D 2016 Cryptomyrus a new genus of Mormyridae Teleostei Osteoglossomorpha with two new species from Gabon West Central Africa ZooKeys 561 117 150 doi 10 3897 zookeys 561 7137 PMC 4768369 PMID 27006619 Van Neer Wim Gonzalez Jerome 2019 A Late Period fish deposit at Oxyrhynchus el Bahnasa Egypt In Peters Joris McGlynn George Goebel Veronika eds Documenta Archaeobiologiae Animals Cultural Identifiers In Ancient Societies PDF Rahden Westfalia Germany Verlag Marie Leidorf ISBN 978 3 89646 674 7 External links Edit nbsp Media related to Mormyridae at Wikimedia Commons nbsp Data related to Mormyridae at Wikispecies Detailed research paper on the sensory and central nervous systems in Gnathonemus petersi Mormyrids in the aquarium Mormyridae African weakly electric fishes including interactive checklist Retrieved from https en wikipedia org w index php title Mormyridae amp oldid 1181022744, wikipedia, wiki, book, books, library,
