The eelpouts are the ray-finned fishfamilyZoarcidae. As the common name suggests, they are somewhat eel-like in appearance. All of the roughly 300 species are marine and mostly bottom-dwelling, some at great depths. Eelpouts are predominantly found in the Northern Hemisphere. The arctic, north pacific and north Atlantic oceans have the highest concentration of species, however species are found around the globe.
The largest member of the family is Zoarces americanus, which may reach 1.1 m in length. Other notable genera include Lycodapus and Gymnelus.
Taxonomy
The eelpout family was first proposed as the family Zoarchidae in 1839 by the English naturalist William John Swainson but the spelling was changed to Zoarcidae after the spelling of the genus Zoarces was corrected by Theodore Gill in 1861.[1] The 5th edition of Fishes of the World classifies this family within the suborderZoarcoidei, within the order Scorpaeniformes.[4] Other authorities classify this family in the infraorder Zoarcales within the suborder Cottoidei of the Perciformes because removing the Scorpaeniformes from the Perciformes renders that taxon non monophyletic.[5]
Fishes of the World mentions four subfamilies but does not assign genera to the subfamilies[4] but these were set out in Anderson and Federov's Annotated Checklist[6] and this has been followed by FishBase[7] and Catalog of Fishes.[8]
Subfamilies and genera
The eelpouts are classified into four subfamilies and 61 genera with around 300 species:[8][1]
The body of eelpouts is relatively elongated and laterally compressed.[9] Their heads are relatively small and ovoid. Juveniles have a more rounded snout and relatively larger eye than adults.[9] Their scales are absent or very small.[10] The dorsal and anal fins are continuous down their bodies up to their caudal fin. They produce the pigment biliverdin, which turns their bones green. This feature has no apparent evolutionary function and is harmless.[11] Overall, there is no sexual dimorphism.[12]
Biology
Little is known about eelpout populations because they often slip through nets in sampling studies, and because some species live in inaccessibly deep habitats. Species for which trophic ecology has been documented are typically, if not always, benthic scavengers or predators.[11][13] At least one species has also adapted to able to breathe air when out of water.[11]
^Swainson, William (1839). On the Natural History and Classification of Fishes, Amphibians, and Reptiles. Vol. 2. London: Longman, Orme, Brown, Greene, & Longmans. pp. 82–83, 184, 283. doi:10.5962/bhl.title.62140.
^Kawahara, R.; Miya, M.; Mabuchi, K.; Lavoué, S.; Inoue, J.G.; Satoh, T.P.; Kawaguchi, A. & Nishida, M. (2008). "Interrelationships of the 11 gasterosteiform families (sticklebacks, pipefishes, and their relatives): a new perspective based on whole mitogenome sequences from 75 higher teleosts". Molecular Phylogenetics and Evolution. 46 (1): 224–36. doi:10.1016/j.ympev.2007.07.009. PMID17709262.
^Belman, Bruce W.; Anderson, M. Eric (May 18, 1979). "Aquarium Observations on Feeding by Melanostigma pammelas (Pisces: Zoarcidae)". Copeia. 1979 (2): 366–369. doi:10.2307/1443432. JSTOR1443432.
