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Monognathus

Monognathus, or onejaw, is the only genus of the family Monognathidae of deep-sea eels. The name comes from the Greek monos meaning "one" and gnathos meaning "jaw", a reference to the large mouth in comparison with the rest of the fish, and also the absence of an upper jaw.

Last revised
Jul 22, 2026
Read time
≈ 2 min
Length
442 w
Citations
8
Source
Wikipedia ↗
Monognathus
M. jesperseni
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Anguilliformes
Suborder: Anguilloidei
Family: Monognathidae
Trewavas, 19371
Genus: Monognathus
Bertin, 1936
Species

15, see text.

Synonyms2
  • Phasmatostoma Myers, 1940

Monognathus, or onejaw, is the only genus of the family Monognathidae of deep-sea eels. The name comes from the Greek monos meaning "one" and gnathos meaning "jaw", a reference to the large mouth in comparison with the rest of the fish, and also the absence of an upper jaw (maxilla and premaxilla bones are absent).3

Description

The dorsal and anal fins lack bony supports and the pectoral fins are missing. The snout has a fang connected to glands, which are venomous in adults.4 These eels are virtually blind, with rudimentary eyes and small olfactory organs, although the male olfactory organs are enlarged, perhaps suggesting a method of "sniffing out" a mate.3

Typical lengths are from 4 to 10 cm (1.5–4 in), the maximum length recorded is 15.9 cm (6.3 in).

Distribution

They are found at depths of over 2,000 m (6,600 ft), and are found in all oceans.53

Species

The fifteen known species are:5

  • Monognathus ahlstromi Raju, 1974 (Paddletail onejaw)
  • Monognathus berteli J. G. Nielsen & Hartel, 1996.
  • Monognathus bertini Bertelsen & J. G. Nielsen, 1987.
  • Monognathus boehlkei Bertelsen & J. G. Nielsen, 1987.
  • Monognathus bruuni Bertin, 1936.
  • Monognathus herringi Bertelsen & J. G. Nielsen, 1987.
  • Monognathus isaacsi Raju, 1974.
  • Monognathus jesperseni Bertin, 1936.
  • Monognathus jesse Raju, 1974.
  • Monognathus nigeli Bertelsen & J. G. Nielsen, 1987.
  • Monognathus ozawai Bertelsen & J. G. Nielsen, 1987.
  • Monognathus rajui Bertelsen & J. G. Nielsen, 1987.
  • Monognathus rosenblatti Bertelsen & J. G. Nielsen, 1987.
  • Monognathus smithi Bertelsen & J. G. Nielsen, 1987.
  • Monognathus taningi Bertin, 1936.
References

References

  1. Van Der Laan, Richard; Eschmeyer, William N.; Fricke, Ronald (11 November 2014). "Family-group names of Recent fishes". Zootaxa. 3882 (1): 1–230. doi:10.11646/zootaxa.3882.1.1. PMID 25543675.
  2. Fricke, Ron; Eschmeyer, William N. & van der Laan, Richard (eds.). "Genera in the family Monognathidae". Catalog of Fishes. California Academy of Sciences. Retrieved 9 November 2024.
  3. BÖHLKE, EUGENIA B.; BÖHLKE, JAMES E.; LEIBY, MARK M.; McCOSKER, JOHN E.; BERTELSEN, E.; ROBINS, CATHERINE H.; ROBINS, C. RICHARD; SMITH, DAVID G.; TIGHE, KENNETH A. (1989). Orders Anguilliformes and Saccopharyngiformes: Part 9, Volume 1. Yale University Press. ISBN 978-1-933789-19-4. JSTOR j.ctvbcd0dm.
  4. Poulsen, Jan Y.; Miller, Michael J.; Sado, Tetsuya; Hanel, Reinhold; Tsukamoto, Katsumi; Miya, Masaki (2018-07-25). "Resolving deep-sea pelagic saccopharyngiform eel mysteries: Identification of Neocyema and Monognathidae leptocephali and establishment of a new fish family "Neocyematidae" based on larvae, adults and mitogenomic gene orders". PLOS ONE. 13 (7) e0199982. Bibcode:2018PLoSO..1399982P. doi:10.1371/journal.pone.0199982. ISSN 1932-6203. PMC 6059418. PMID 30044814.
  5. Froese, Rainer; Pauly, Daniel (eds.). "Family Monognathidae". FishBase. June 2011 version.