Teeth well developed, especially on the vomer; pectorals well developed; eyes large and covered with skin; dorsal fin origin over or slightly before pectoral base; lateral line conspicuous; vertebrae 120-216.
As noted by D. G. Smith, in Böhlke (1989:432-40), this family is poorly diagnosed and is of uncertain affinity.
Four genera, Congresox, Cynoponticus, Muraenesox, and probably Sauromuraenesox, with about eight species.
Family NEMICHTHYIDAE (85)—snipe eels. Marine (bathy- and mesopelagic); Atlantic, Indian, and Pacific
Extremely long, nonocclusible upper and lower jaws (except in fully mature males), with upper jaw longer than lower; body very elongate; pectoral fin present; dorsal and anal fins confluent with caudal; eyes large; preopercle absent; frontals only partially fused in some; lateral line complete; anus a short distance behind pectoral fin (Avocettina) or under pectoral fin (the other two genera); vertebrae 170-220 in LLabichthys and Avocettina to over 750 in Nemichthys (species of this genus have a caudal filament that is frequently lost and thus precludes accurate counts).
Male snipe eels undergo a marked transformation at sexual maturity with, for example, the jaws undergoing a drastic shortening and loss of teeth. The two sexes of some species were at one time placed in separate genera and even in separate suborders.
Three genera, Avocettina (about four species), LLabichthys (two species), and Nemichthys (three species), with about nine species (D. G. Smith and J. G. Nielsen in Bohlke, 1989:441-59).
Family CONGRIDAE (86)—conger eels. Marine; tropical to temperate, Atlantic, Indian, and Pacific.
Lateral line complete; pectoral fin usually present; branchiostegal rays 8-22; vertebrae 105-225.
Three subfamilies with 32 genera and roughly 160 species (e.g., D. G. Smith in Böhlke, 1989:460-567; Castle and Randall, 1999; Smith and Karmovskaya, 2003; Greenfield and Niesz, 2004).
Subfamily Heterocongrinae (garden eels). Dorsal and anal fin rays unsegmented; pectoral fin minute or absent; body very elongate and slender; mouth short and lower jaw projecting beyond upper. Garden eels have the interesting habit of hovering above their sand burrows in large colonies (giving the appearance of a garden), with their tail down and the body relatively straight up.
Two genera, Gorgasia and Heteroconger.
Subfamily Bathymyrinae. Dorsal and anal fin rays unsegmented; pectoral fin well developed; posterior nostril below mideye level.
About five genera, Ariosoma, Bathymyrus, Chiloconger, Parabathymyrus, and Paraconger.
Subfamily Congrinae. Dorsal and anal fin rays segmented; pectoral fin well developed; posterior nostril at or above mideye level.
About 25 genera—e.g., Acromycter, Conger (= the older but suppressed generic name Leptocephalus), Gavialiceps, Gnathophis, Hildebrandia, Lumiconger (a luminescent eel off northern Australia described in 1984), Macrocephenchelys (this genus was once placed in its own family), Rhechias, Rhynchoconger, Uroconger, and Xenomystax.
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