Eel

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Eels
Temporal range: Cenomanian–recent[1]
Anguilla japonica
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Superorder: Elopomorpha
Order: Anguilliformes
L. S. Berg, 1943
Type genus
Anguilla
Suborders
Protanguilloidei
Synaphobranchoidei
Muraenoidei
Chlopsoidei
Congroidei
Moringuoidei
Saccopharyngoidei
Anguilloidei

Eels are

predators
.

The term "eel" is also used for some other eel-shaped fish, such as

catadromous genus Anguilla and the freshwater moray,[5] which spend most of their life in freshwater, the anadromous rice-paddy eel, which spawns in freshwater, and the freshwater snake eel Stictorhinus.[6]

Spotted moray eel in a tank, 2016

Description

The European conger is the heaviest of all eels.

Eels are elongated fish, ranging in length from 5 cm (2 in) in the one-jawed eel (

caudal fin, forming a single ribbon running along much of the length of the animal.[1] Eels swim by generating waves that travel the length of their bodies. They can swim backward by reversing the direction of the wave.[8]

Most eels live in the shallow waters of the

Anguilla regularly inhabit fresh water, but they, too, return to the sea to breed.[9]

The heaviest true eel is the European conger. The maximum size of this species has been reported as reaching a length of 3 m (10 ft) and a weight of 110 kg (240 lb).[10] Other eels are longer, but do not weigh as much, such as the slender giant moray, which reaches 4 m (13 ft).[11]

Life cycle

Eels begin life as flat and transparent

weirs
, dam walls, and natural waterfalls.

catadromous
) eel
  • Eel eggs hatch firstly into the leptocephalus larval stage.
    Eel eggs hatch firstly into the leptocephalus larval stage.
  • Larval eels become glass eels as they transition from the ocean to fresh water.
    Larval eels become
    glass eels
    as they transition from the ocean to fresh water.
  • As freshwater elvers, eels work their way upstream.
    As freshwater elvers, eels work their way upstream.
  • Mature silver stage eels migrate back to the ocean to mate.
    Mature silver stage eels migrate back to the ocean to mate.

Ballisodare were greatly improved by the hanging of loosely plaited grass ladders over barriers, enabling elvers to ascend more easily.[13]

Classification

Several sets of classifications of eels exist; some, such as

include additional eel families, which are noted below.

Genomic studies indicate that there is a

monophyletic group that originated among the deep-sea eels.[14]

Taxonomy

The earliest fossil eels are known from the Late Cretaceous (Cenomanian) of Lebanon. These early eels retain primitive traits such as pelvic fins and thus do not appear to be closely related to any extant taxa. Body fossils of modern eels do not appear until the Eocene, although otoliths assignable to extant eel families and even some genera have been recovered from the Campanian and Maastrichtian, indicating some level of diversification among the extant groups prior to the Cretaceous-Paleogene extinction, which is also supported by phylogenetic divergence estimates. One of these otolith taxa, the mud-dwelling Pythonichthys arkansasensis, appears to have thrived in the aftermath of the K-Pg extinction, based on its abundance.[15][16][17]

Extant taxa

garden eel

Taxonomy based on Nelson, Grande and Wilson 2016.[18]

  • Suborder Protanguilloidei
    • Family
      Protanguillidae
  • Suborder Synaphobranchoidei
    • Family
      Synaphobranchidae
      (cutthroat eels) [incl. Dysommidae, Nettodaridae, and Simenchelyidae]
  • Suborder Muraenoidei
  • Suborder Chlopsoidei
  • Suborder Congroidei
  • Suborder Moringuoidei
  • Suborder Saccopharyngoidei
    • Family
      Eurypharyngidae
      (pelican eels, umbrellamouth gulpers)
    • Family
      Saccopharyngidae
    • Family
      Monognathidae
      (onejaw gulpers)
    • Family
      Cyematidae
      (bobtail snipe eels)
  • Suborder Anguilloidei
    • Family Anguillidae (freshwater eels)
    • Family
      Nemichthyidae
      (snipe eels)
    • Family
      Serrivomeridae
      (sawtooth eels)

In some classifications, the family

Saccopharyngiformes
.

The

catfishes
.

Phylogeny

Phylogeny based on Johnson et al. 2012.[19]

Anguilliformes
Protanguilloidei

Protanguillidae

Synaphobranchoidei

Synaphobranchidae

Muraenoidei

Heterenchelyidae

Myrocongridae

Muraenidae

Chlopsoidei

Chlopsidae

Congroidei
Moringuoidei

Moringuidae

Saccopharyngoidei

Eurypharyngidae

Saccopharyngidae

Monognathidae

Cyematidae

Anguilloidei

Nemichthyidae

Serrivomeridae

Anguillidae

Extinct taxa

Anguillavus, one of the earliest known eels from the Sannine Limestone
Paranguilla, an Eocene eel from Monte Bolca

Based on the Paleobiology Database:[20][21]

Commercial species

Main commercial species
Common name Scientific name Maximum
length
Common
length
Maximum
weight
Maximum
age
Trophic
level
FishBase
FAO
ITIS
IUCN status
American eel Anguilla rostrata (Lesueur, 1817) 152 cm 50 cm 7.33 kg 43 years 3.7 [22] [23] EN IUCN 3 1.svg
Endangered[24]
European eel Anguilla anguilla (Linnaeus, 1758) 150 cm 35 cm 6.6 kg 88 years 3.5 [25] [26] [27] CR IUCN 3 1.svg
Critically endangered[28]
Japanese eel Anguilla japonica Temminck & Schlegel, 1846 150 cm 40 cm 1.89 kg 3.6 [29] [30] [31] EN IUCN 3 1.svg
Endangered[32]
Short-finned eel Anguilla australis Richardson, 1841 130 cm 45 cm 7.48 kg 32 years 4.1 [33] [34] EN IUCN 3 1.svg
Near Threatened[35]

Use by humans

Eel picker in Maasholm, sculpture by Bernd Maro
Green water culture system for Japanese eel
Positioning eel traps in Inle Lake (Myanmar)

Freshwater eels (

Bolsena Lake and pond eels from Cabras, Sardinia. In northern Germany, the Netherlands, the Czech Republic, Poland, Denmark, and Sweden, smoked eel is considered a delicacy
.

Elvers, often fried, were once a cheap dish in the United Kingdom. During the 1990s, their numbers collapsed across Europe.[40] They became a delicacy, and the UK's most expensive species.[41]

Eels, particularly the moray eel, are popular among marine aquarists.

Eel blood is toxic to humans

Charles Robert Richet in his Nobel Prize-winning research which discovered anaphylaxis (by injecting it into dogs and observing the effect).[citation needed] The poison used by Richet was actually obtained from sea anemones.[46]

Eelskin leather is highly prized. It is very smooth and exceptionally strong. It does not actually come from eels, but rather from the

jawless fish
which is also known as the slime eel.
[47][48]

High consumption of eels is seen in European countries leading to those eel species being considered endangered.

In culture

The large lake of Almere, which existed in the early Medieval Netherlands, got its name from the eels which lived in its water (the Dutch word for eel is aal or ael, so: "ael mere" = "eel lake"). The name is preserved in the new city of Almere in Flevoland, given in 1984 in memory of this body of water on whose site the town is located.

The daylight passage in the spring of

Thames was at one time called "eel fare". The word 'elver' is thought to be a corruption of "eel fare".[13]

A famous attraction on the French Polynesian island of Huahine (part of the Society Islands) is the bridge across a stream hosting three- to six-foot-long eels, deemed sacred by local culture.

Eel fishing in

Danzig plays an important role in Günter Grass' novel The Tin Drum
. The cruelty of humans to eels is used as a metaphor for Nazi atrocities, and the sight of eels being killed by a fisherman triggers the madness of the protagonist's mother.

Sinister implications of eels fishing are also referenced in Jo Nesbø's Cockroaches, the second book of the Harry Hole detective series. The book's background includes a Norwegian village where eels in the nearby sea are rumored to feed on the corpses of drowned humans, making the eating of these eels verge on cannibalism.

Sustainable consumption

In 2010, Greenpeace International added the European eel, Japanese eel, and American eel to its seafood red list.[49] Japan consumes more than 70% of the global eel catch.[50]

  • Eel fishing boat in France
    Eel fishing boat in France
  • Special boats to transport live eels Comacchio
    Special boats to transport live eels Comacchio
  • Eel trap in Denmark around 1900
    Eel trap in Denmark around 1900
  • Gerookte paling (Dutch for smoked eel)
    Gerookte paling (Dutch for smoked eel)

Etymology

The English name "eel" descends from

áhi, Avestan aži, Armenian auj, iž, Old Church Slavonic *ǫžь, all from Proto-Indo-European *h₁ogʷʰis). The word also appears in the Old English word for "hedgehog", which is igil (meaning "snake eater"), and perhaps in the egi- of Old High German egidehsa "wall lizard".[52][53]

According to this theory, the name

ahihán). In this theory, the ελλερο- is an adjective form of an older word, ελλυ, meaning "snake", which is directly comparable to Hittite ellu-essar- "snake pit". This myth likely came to Greece via Anatolia. In the Hittite version of the myth, the dragon is called Illuyanka
: the illuy- part is cognate to the word illa, and the -anka part is cognate to angu, a word for "snake". Since the words for "snake" (and similarly shaped animals) are often subject to taboo in many Indo-European (and non-Indo-European) languages, no unambiguous Proto-Indo-European form of the word for eel can be reconstructed. It may have been *ēl(l)-u-, *ēl(l)-o-, or something similar.

Timeline of genera

See also

References

  1. ^ a b Froese, Rainer, and Daniel Pauly, eds. (2009). "Anguilliformes" in FishBase. January 2009 version.
  2. ^ Pl. 661 in Garsault, F. A. P. de 1764. Les figures des plantes et animaux d'usage en medecine, décrits dans la Matiere Medicale de Mr. Geoffroy medecin, dessinés d'après nature par Mr. de Gasault, gravés par Mrs. Defehrt, Prevost, Duflos, Martinet &c. Niquet scrip. [5]. - pp. [1-4], index [1-20], Pl. 644–729. Paris.
  3. ^ "WoRMS - World Register of Marine Species - Anguilliformes". www.marinespecies.org.
  4. ^ "WoRMS - World Register of Marine Species - Saccopharyngiformes". www.marinespecies.org.
  5. S2CID 204150660
    – via www.publish.csiro.au.
  6. ^ "Family OPHICHTHIDAE" (PDF).
  7. ^ .
  8. ^ Long Jr, J. H., Shepherd, W., & Root, R. G. (Loot). Manueuverability and reversible propulsion: How eel-like fish swim forward and backward using travelling body waves". In: Proc. Special Session on Bio-Engineering Research Related to Autonomous Underwater Vehicles, 10th Int. Symp. (pp. 118–134).
  9. .
  10. ^ Conger conger, European conger: fisheries, gamefish, aquarium. Fishbase.org
  11. ^ FishBase Archived 10 November 2013 at the Wayback Machine. FishBase (15 November 2011).
  12. PMC 7553983
    .
  13. ^ a b Campbell, Lady Colin (1886). A Book of the Running Brook: and of Still Waters. New York: O. Judd Co. pp. 9, 18.
  14. PMID 20053660
    .
  15. .
  16. .
  17. .
  18. .
  19. ^ "PBDB". paleobiodb.org. Retrieved 21 February 2024.
  20. PMID 27514517
    .
  21. ^ Froese, Rainer; Pauly, Daniel (eds.) (2012). "Anguilla rostrata" in FishBase. May 2012 version.
  22. ^ "Anguilla rostrata". Integrated Taxonomic Information System. Retrieved 20 May 2015.
  23. . Retrieved 12 November 2021.
  24. ^ Froese, Rainer; Pauly, Daniel (eds.) (2012). "Anguilla anguilla" in FishBase. May 2012 version.
  25. ^ Anguilla anguilla (Linnaeus, 1758) FAO, Species Fact Sheet. Retrieved 20 May 2012.
  26. ^ "Anguilla anguilla". Integrated Taxonomic Information System. Retrieved 20 May 2012.
  27. . Retrieved 12 November 2021.
  28. ^ Froese, Rainer; Pauly, Daniel (eds.) (2012). "Anguilla japonica" in FishBase. May 2012 version.
  29. ^ Anguilla japonica, Temminck & Schlegel, 1846 FAO, Species Fact Sheet. Retrieved May 2012.
  30. ^ "Anguilla japonica". Integrated Taxonomic Information System. Retrieved 20 May 2012.
  31. . Retrieved 4 January 2018.
  32. ^ Froese, Rainer; Pauly, Daniel (eds.) (2012). "Anguilla australis" in FishBase. May 2012 version.
  33. ^ "Anguilla australis". Integrated Taxonomic Information System. Retrieved 20 May 2012.
  34. . Retrieved 12 November 2021.
  35. ^ "Swamp Eels". Encyclopedia of Life. Retrieved 24 June 2022.
  36. ^ Bhuyan, Avantika (30 March 2018). "The little fish in big rivers". The Live Mint. Retrieved 24 June 2022.
  37. ^ Acou, Anthony, et al. "Assessment of the Quality of European Silver Eels and Tentative Approach to Trace the Origin of Contaminants – A European Overview." The science of the total environment. 743 (2020): n. pag. Web.
  38. ^ "Buber's Basque Page: Angulas".
  39. ^ Champken, Neil (2 June 2006). "Would you pay £600 for a handful of baby eels?". theguardian.com. Retrieved 7 April 2015.
  40. ^ Leake, Jonathan (7 February 2015). "EU's eel edict costs UK £100m". The Sunday Times. Archived from the original on 10 July 2015. Retrieved 7 April 2015.
  41. ^ "Poison in the Blood of the Eel" (PDF). 9 April 1899. Retrieved 22 January 2010.
  42. ^ "The plight of the eel (mentions that "Only 0.1 ml/kg is enough to kill small mammals, such as a rabbit..." BBC online. Retrieved 22 January 2010.
  43. ^ "Blood serum of the eel." M. Sato. Nippon Biseibutsugakukai Zasshi (1917), 5 (No. 35), From: Abstracts Bact. 1, 474 (1917)
  44. ^ "Hemolytic and toxic properties of certain serums." Wm. J. Keffer, Albert E. Welsh. Mendel Bulletin (1936), 8 76–80.
  45. ^ "Charles Robert Richet". encyclopedia.com.
  46. ^ snopes (4 December 2015). "Eelskin Demagnitizes : snopes.com". Snopes. Retrieved 21 April 2010.
  47. ^ Barss, William (1993), "Pacific hagfish, Eptatretus stouti, and black hagfish, E. deani: the Oregon Fishery and Port sampling observations, 1988–92", Marine Fisheries Review (Fall, 1993), archived from the original on 7 March 2012, retrieved 21 April 2010
  48. ^ "Greenpeace Seafood Red list". Greenpeace International.
  49. ^ "Indonesia eel hot item for smugglers". The Japan Times. 29 July 2013. Retrieved 30 July 2013.
  50. ISBN 3-85124-667-5.{{cite book}}: CS1 maint: location missing publisher (link
    )
  51. .
  52. .


Further references

External links

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