Synbranchiformes

Article By:

Boschung, Herbert T. Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama.

Last reviewed:June 2020

DOI:https://doi.org/10.1036/1097-8542.674200

An order of eel-like actinopterygian fishes, commonly called swamp eels. Members of the order Synbranchiformes (synbranchiforms) are among the most highly specialized fishes. They are characterized by the following features: a usually scaleless eel-like body that lacks pelvic fins, with the pectoral fins being present or absent; gill openings that are entirely ventral and often confluent across the breast; premaxillae that lack ascending processes and are nonprotrusible; ectopterygoid bones that are enlarged; endopterygoids that are reduced or absent; the presence or absence of a swim bladder; and gills that are poorly developed, with respiration in some species being accomplished in part by highly vascularized buccopharyngeal pouches. The order Synbranchiformes has no fossil record and comprises 3 families, 13 genera, and about 120 species (all but three of these are freshwater inhabitants). Synbranchiforms are thought to form a monophyletic group with the smegmamorphs. See also: Actinopterygii

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