Wide-mouth Moray, Gymnothorax eurygnathos

Wide-Mouth Moray, Gymnothorax eurygnathos, Juvenile. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, Mexico, March 2013. Length: 9.8 cm (3.85 inches). Tail: 48%.

The Wide-mouth Moray, Gymnothorax eurygnathos, is a member of the Moray and Snake Moray Eel or Muraenidae Family, that is also known as the Equatorial Moray and in Mexico as morena boca ancha. There are one hundred sixteen global members of the genus Gymnothorax, of which eighteen are found in Mexican waters, nine in the Atlantic and nine in the Pacific Ocean.

The Wide-mouth Moray has a stout elongated cylindrical body that tapers to a narrow cylindrical tail with a slender tip. They are dark brown in color with small tan colored irregular blotches covering the body, anal and dorsal fins that are smaller and more numerous on the head. The tail has a pale yellow tip, a key to the identification. The head is large and broad with a short snout, small eyes, with the anterior nostril being a short tube and the posterior nostril being a pore above and before the anterior margin of the eye, with short wide jaws, with the top jaw projecting slightly beyond the lower jaw, that are equipped with stout triangular serrated teeth on both sides. The traditional black spot on the gill cover of morays is not readily visible in this species. The anal and dorsal fins are covered with skin, and continuous with the caudal fin. The dorsal fin originates behind the gill openings. The tail is less than one-half the body length. They do not have pectoral fins or scales.

The Wide-mouth Moray is found over soft sandy bottoms adjacent to rocky reefs from depths between 30 m (100 feet) and 396 m (1,300 feet). They reach a maximum of 47 cm (19 inches) in length. They are assumed to be voracious nocturnal ambush predators with poor eyesight that utilize a keen sense of smell to seek out prey, consuming on small fish and invertebrates including crabs, octopus, and shrimp. They open and close their mouths frequently, an action that is required for respiration. Reproduction is viviparous with eggs and sperm broadcast into the water generating pelagic eggs and larvae that may drift in oceanic currents before settling out on the bottom.  The Wide-mouth Moray is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.

The Wide-Mouth Moray is a resident of Mexican waters of the Pacific Ocean but has a limited distribution being found only from Mazatlán, Sinaloa, southward along the west coast of the mainland to Guatemala. The fish photographed below, if the identification is correct, documents a significant range extension to the tip of the Baja and Baja California Sur, for this species.

The Wide-Mouth Moray Eel is most likely confused with the Spottail Moray, Gymnothorax equatorialis (narrower tail with very elongated, widely spaced, terminal spots) and the Small Spotted Moray Eel, Gymnothroax phalarus (dark tipped tail, oval spots).

From a conservation perspective the Wide-Mouthed Moray has not been formally evaluated and is currently considered as Data Deficient. They are exceedingly rare and are therefore of limited interest to most and if encountered are visually intimidating.