Body very elongated. Dorsal fin originating above branchial opening, very long, together with anal fin confluent with caudal fin. Pectoral and pelvic fin absent. Head pointed with a distinctly elevated occipital region. Anterior nostril tubular. Posterior nostril round to oval opening in front of eye. Large mouth, its cleft extending back well behind eye. Jaw arched, with many fang-like teeth, which are visible even when mouth is closed. No scales on body.
body dark brown with numerous yellow blotches and dots arranged in longitudinal rows. Snout and cheeks light brown with yellow dots.
common 50 - 100 cm (max. 120 cm).
Gymnothorax unicolor: jaws not arched; body uniformly colored.
Muraena helena: jaws not arched; both posterior and anterior nostrils have tubes.
Congridae, Muraenecosidae and Ophichthidae (in part): pectoral fin present.
BIOLOGY / ECOLOGY
Feeds on fishes and large invertebrates. Eggs and larvae apparently pelagic.