Common name: True Eels

The Order Anguilliformes, or true eels, contains 20 families and about 820 species, and includes some very bizarre groups.

Species are usually long and slender, with long-based dorsal and anal fins that are continuous with the caudal fin (if present) in all but one species. All species lack pelvic fins, and some groups lack pectoral fins. Scales are usually absent, or if present, are embedded in skin.

True eels range in size from about 5 cm to 4 metres in length, and all species pass through a pelagic, ribbon- or leaf-like larval stage called a leptocephalus larva.

Most species are nocturnal and live in shallow waters, burrowing into sandy or muddy bottoms, or hiding in crevices, caves and holes on coral and rocky reefs. Many species live at the bottom of the deep-sea, and a number of bizarre families inhabit the mesopelagic twilight zone or are bathypelagic.

Only members of the family Anguillidae regularly inhabit freshwater, and undertake long migrations to breed offshore in the deep water.

Most true eels are predators and belong to one of three families: Congridae (Conger eels), Muraenidae (Moray Eels) and Ophichthidae (snake eels and worm eels).

Some species are excellent food fish and form the basis of very important commercial fisheries.

In August 2011, a new family, the Protoanguillidae, comprising a single genus and species, Protanguilla palau, with a separate caudal fin and many other primitive characters was described. Morphological and molecular data suggest that this species is the most primitive living member of the Anguilliformes (Johnson et al. 2011).

The fossil record dates back to the Cretaceous about 100 million years ago.

Author: Dianne J. Bray

Cite this page as:
Dianne J. Bray, Eels, ANGUILLIFORMES in Fishes of Australia, accessed 17 Jun 2024, https://fishesofaustralia.net.au/home/order/2

Order References

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Forey, P.L., Yi, L., Patterson, C. & Davies, C.E. 2003. Fossil fishes from the Cenomanian (Upper Cretaceous) of Namoura, Lebanon. J. Syst. Palaeontol. 1: 227–330.

Hoese, D.F., D.J. Bray, J.R. Paxton & G.R. Allen. 2006. Fishes. In Beesley, P.L. & A. Wells. (eds.) Zoological Catalogue of Australia. Volume 35. ABRS & CSIRO Publishing: Australia, Part 1: xxiv-670.

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Johnson, D.G., Ida, H., Sakaue, J., Sado, T., Asahida, T. & Miya, M. 2011. A 'living fossil' eel (Anguilliformes: Protoanguillidae, fam. nov.) from an undersea cave in Palau. Proceedings of the Royal Society B [Date published published online 17 August 2011]

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Tsukamoto, K., Nakai, I. & Tesch, F.W. 1998. Do all freshwater eels migrate? Nature 396: 635–636.

Tsukamoto, K., Aoyama, J. & Miller, M.J. 2002. Migration, speciation, and the evolution of diadromy in anguillid eels. Can. J. Fish. Aquat. Sci. 59: 1989–1998.

Tsukamoto, K., Miller, M.J., Kotake, A., Aoyama, J. & Uchida, K. 2009. The origin of diadromous fish migration: the random escapement hypothesis. In Challenges for diadromous fishes in a dynamic global environment, vol. 69 (eds A. Haro et al.), pp. 45–61. Bethesda, MD: American Fisheries Society.

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