Wide-mouth Moray, Gymnothorax eurygnathos
The Wide-mouth Moray, Gymnothorax eurygnathos, whose common Spanish name is morena boca ancha, is a member of the Moray and Snake Moray Eel or Muraenidae Family, known collectively as morenas in Mexico. This fish is also known as the Equatorial Moray. There are one hundred sixteen global members of the genus Gymnothorax, eighteen of which are found in Mexican waters, nine in the Atlantic and nine in the Pacific.
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 are exceedingly rare, poorly studied, and a poorly documented species with very little known about its behavioral patterns. They are found over soft sandy bottoms adjacent to rocky reefs from depths between 100 and 1,300 feet. They reach a maximum length of 47 cm (19 inches). They are assumed to be voracious nocturnal ambush predators with poor eye sight 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.
In Mexican waters the Wide-Mouth Moray has a limited distribution being found only from Mazatlán to Guatemala along the west coast of the mainland. The fish photographed below, if the identification is correct, documents a significant range extension to the tip of the Baja for this species.
The Wide-Mouth Moray Eels are 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).
The Wide-Mouthed Morays are exceedingly rare is if caught are a “catch and release.” Visually they are most intimidating.
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%.