Marine fishes, some species in or occasionally entering freshwater. Body snake-like or worm-like, more or less rounded in cross section. Throat swollen. Eye usually small and just above mouth. Snout pointed. Anterior nostril tubular, near tip of snout. Posterior nostril low on head, on lip, or opening inside of mouth. Mouth moderate to large, terminal or inferior. Teeth variable in form, from fang-like to conical to molariform to villiform. Gill opening midlateral to completely ventral, round or slit-like. Dorsal, anal, pectoral and caudal fins present or absent; when caudal fin present, confluent with dorsal and anal fins, when absent, tip of tail often hard and pointed. Lateral line complete, usually with well developed pores on head and body. Scales absent. Color: highly variable, from uniform light or dark to various patterns of spots, stripes, or bars; usually darker dorsally than ventrally.|
Similar familis occurring in the area: Muraenidae: Posterior nostril high on head, above or before eye, a simple pore or in a tube. Muraenesocidae: throat not swollen.
Remarks. Ophichthyids occur in a wide variety of habitats from muddy estuaries to coral reefs to the midwater realm, from the shore to depths of 700-800 m or more, but most occur in less than 200 m.