Anguilliformes

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A large order of actinopterygian fishes containing the true eels. This group, also known as the Apodes, now includes the former order Saccopharyngiformes or Lyomeri (gulpers or gulper eels). The Anguilliformes have a ribbonlike, larval stage in development. The chief characters of the Aguilliformes include a pectoral girdle which, when present, is free from the head and suspended from the vertebral column; no symplectic, mesocoracoid, and posttemporal bones; pectoral fin present or absent; absence of a pelvic fin and girdle in recent forms; no fin spines; elongate body with numerous vertebrae; scales present or absent; paired orbitosphenoids; and restricted gill apertures.

The typical eels (suborder Anguilloidei) have a swim bladder with a duct, a small opercle, and 6–22 branchiostegals, and the premaxilla, mesethmoid, and lateral ethmoids are fused into a tooth-bearing ethmopremaxillary block that separates the maxillae. Eels, which date from the Upper Cretaceous, are classified in about 20 Recent families and 110 genera, and there are several hundred species. See also Eel.

The gulpers (suborder Saccopharyngoidei) have degenerative adaptations, including loss of swim bladder, opercle, bran-chiostegal rays, caudal fin, scales, and ribs. The tremendous mouth is greatly modified (see illustration), the eyes are tiny and placed far forward, the pharynx is enormously distensible, and the tail is slender and tapering. These are rare oceanic fishes, classified in three families, three genera, and nine species. Their fossil history is unknown. See also Actinopterygii; Osteichthyes.

Gulper eel (Eupharynx bairdi). (After G. B. Goode and T. H. Bean, Oceanic Ichthyology, U.S. Nat. Mus. Spec. Bull. no. 2, 1896)

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