Synopsis
The high level of encephalization in Heterotis niloticus is due, in part, to a voluminous lobus vagalis, which has the form of a cauliflower and receives the fibers of a strong branch of the 10th (vagal) nerve. This vagal branch comes from a special branchial apparatus, the epibranchial organ, considered to be an air-breathing organ by some, and a microphagous apparatus by others. This organ has a spiral, snail-like form and its lumen is a blind-alley. Its study in a juvenile fish 10 cm SL shows that it has two canals: a peripheric one for water entrance and a central one for food exit. The epithelium between these two canals contains numerous gustatory buds, the innervation of which constitutes the branch of the vagal nerve. This epithelium is also very rich in mucous cells, which probably correspond to a muco-microphagous feeding apparatus. The exit canal, which receives the mucous string enriched with food particles, enters directly into the oesophagus. Striated muscles, attaching along the spiral tours of the epibranchial organ, probably serve as the motor that pumps water in and out and supplies the classical ciliary apparatus of the mucophagous feeding organs.
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Bauchot, R., J.E. Randall, J.M. Ridet & M.L. Bauchot. 1989. Encephalization in tropical teleost fishes and comparison with their mode of life. J. Hirnf. 30: 245–269.
Daget, J. 1957. Mémoires sur la biologie des poissons du Niger moyen. III. Reproduction et croissance d'Heterotis niloticus Ehrenberg. Bull. I.F.A.N. 19: 297–323.
Daget, J. & F. d'Aubenton. 1957. Développement et morphologie du crne d'Heterotis niloticus. Bull. I.F.A.N. 19: 881–936.
D'Aubenton, F. 1955a. Sur le rle de l'organe suprabranchial d'Heterotis niloticus Ehrenberg (Téléostéen). C.R. Acad. Sci. Paris 241: 113–114.
D'Aubenton, F. 1955b. Etude de l'appareil branchiospinal et de l'organe suprabranchial d'Heterotis niloticus Ehrenberg, 1827. Bull. I.F.A.N. 17: 1179–1201.
D'Aubenton, F. & J. Daget. 1961. Heterotis Ehrenberg, 1829, and Clupisudis Swainson, 1839 (Pisces): proposal to place on the official list of generic names in zoology. Bull. Zool. Nomencl. 24: 291–293.
Greenwood, P.H. 1966. The caudal fin skeleton in osteoglossid fishes. Ann. Mag. Nat. Hist. 9: 581–597.
Greenwood, P.H. 1971. Hyoid and ventral gill arch musculature in osteo-glossomorph fishes. Bull. Brit. Mus. (Nat. Hist.) Zool. 22: 3–55.
Hyrtl, J. 1854. Beitrag zur Anatomie von Heterotis ehrenbergii C. V Denksch. Kaiserl. Akad. Wiss. Math. Naturw. Wien 8: 73–88.
Kershaw, D.R. 1976. A structural and functional interpretation of the cranial anatomy in relation to the feeding of osteoglossoid fishes and a consideration of their phylogeny. Trans. Zool. Soc. London 33: 173–252.
Marlier, G. 1938. Considerations sur les organes accessoires servant à la respiration aérienne chez les Téléostéens. Ann. Soc. Roy. Zool. Belg. 69: 163–185.
Meunier, F.J. 1984. Structure et minéralisation des écailles de quelques Osteoglossidae (Ostéichthyens, Téléostéens). Ann. Sci. Natur., Zool. 6: 111–124.
Nelson, G.J. 1967. Epibranchial organs in lower teleostean fishes. J. Zool. 153: 71–89.
Nelson, G.J. 1968. Gill arches of teleostean fishes of the division Osteoglossomorpha. J. Linn. Soc. (Zool.) 47: 261–277.
Nelson, G.J. 1969. Infraorbital bones and their bearing on the phylogeny and geography of osteoglossomorph fishes. Amer. Mus. Novit. 2394: 1–37.
Ridet, J.M. & R. Bauchot. 1990. Analyse quantitative de l'encéphale des Télëostéens: caractères évolutifs et adaptatifs de l'encéphalisation. I. Généralités et analyse globale. J. Hirnf. 31: 51–63.
Ridewood, W.G. 1905. On the cranial osteology of the fishes of the families Osteoglossidae, Pantodontidae and Phractolaemidae. J. Linn. Soc. (Zool.) 29: 252–282.
Rüppell, J. 1829. Beschreibung und Abbildungen mehrerer neuer Fische im Nil endeckt. Frankfurt am Main. 12pp. + 3 pl.
Taverne, L. 1967. Le squelette caudal des Mormyriformes et des Ostéoglossomorphes. Bull. Acad. Roy. Belg. 53: 663–678.
Taverne, L. 1974. Sur la presence d'organes cérébraux inconnus chez l'ostéoglossidé africain Heterotis (Ehrenberg) Cuvier et Valenciennes, 1846. Bull. Acad. Roy. Belg. 60: 346–349.
Taverne, L. 1976. Quelques considérations sur I'ostéologie et la phylogenése des Téléostéens fossiles et actuels du super-ordre des Ostéoglossomorphes. Rev. Trav. Inst. Pches Marit. 40: 758–761.
Taverne, L. 1977. Ostéologie, phylogenèse et systématique des Téléostéens fossiles et actuels du super-ordre des Ostéoglossomorphes. I. Ostéologie des genres Hiodon, Eohiodon, Lycoptera, Osteoglossum, Scleropages, Heterotis et Arapaima. Mém. Acad. Roy. Belg. 42: 1–235.
Valenciennes, A. in Cuvier G. & A. Valenciennes 1847. Histoire naturelle des Poissons. T 19, Bertrand Ed., Paris 465–479.
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Bauchot, R., Ridet, JM. & Diagne, M. The epibranchial organ, its innervation and its probable functioning in Heterotis niloticus (Pisces, teleostei, osteoglossidae). Environ Biol Fish 37, 307–315 (1993). https://doi.org/10.1007/BF00004638
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DOI: https://doi.org/10.1007/BF00004638