California Moray, Gymnothorax mordax
California Moray Eel, Gymnothorax mordax. Fish caught from coastal waters off San Diego, California, July 2019. Length: 88 cm (2 feet 11 inches). Catch, photograph, and identification courtesy of Josh Leisen (joshadventures.com), Gaylord, Michigan.
California Moray Eel, Gymnothorax mordax. Fish courtesy of the commercial fishermen of the greater Los Cabos area, Baja California Sur, September 2009. Length: 94 cm (3 feet 1 inch). Tail: 49%.
California Moray Eel, Gymnothorax mordax. Underwater photograph taken in coastal waters off Catalina Island, California, July 2019. Photograph and identification courtesy of Bob Hillis, Ivins, Utah.
The California Moray, Gymnothorax mordax, is a member of the Moray and Snake Eel or Muraenidae Family, and is known in Mexico as morena de California. Globally, there are one hundred sixteen members in the genus Gymnothorax, of which eighteen are found in Mexican waters, nine in the Atlantic and nine in the Pacific Ocean.
The California Moray has a stout elongated muscular compressed body that tapers gradually to a rounded tail. They are light yellow-brown in color with irregular fine dark brown spots or mottling. They quickly fade to a uniform gray-brown upon death. They have a large black spot covering their gill openings. Their head is large and bulbous with small eyes, tube nostrils, and a large mouth equipped with visible canine teeth and prominent jaws. Their jaws have two rows of pointed conical unserrated teeth with the outer row being smaller than the inner row; their lower jaw also has five rows of teeth at the front. Their anal fin originates before mid-body and their dorsal fin originates before the gill openings; both are covered with skin. Their tail is approximately 50% of body length. They do not have pectoral or pelvic fins, gill covers or scales. They are covered with thick yellow mucus, which provides them with protection from abrasion.
The California Moray is a common inhabitant of shallow reef areas found within cracks and crevices in the subtidal zone at depths up to 40 m (130 feet). They reach a maximum of 1.52 m (5 feet 0 inches) in length. As of January 1, 2024, the International Game Fish Association world record stood at 4.8 kg (10 lbs 8 oz) with the fish caught from within San Diego Bay, San Diego, California in August 2018. They take shelter during the day backing into crevices within rocky structure with only their head protruding. Their body shape and the lack of fins, scales, or gill covers allow them to move quickly in and out of rocky crevices. They are voracious nocturnal ambush predators with poor eyesight that utilize their keen sense of smell to seek out prey, that consume crabs, fish, octopus, and shrimp. They are also known for a unique adaptation: a second set of jaws inside their throat that springs forward to help them swallow food. Octopus is one of their favorite food, however the octopus ink fowls their smell for up to two hours. They open and close their mouth frequently, an action required for respiration. They have a symbiotic relationship with the Red Rock Shrimp, Lysmata californica, that inhabit the same burrows and serve as cleaners removing food and parasites. In return, the California Moray provides protection. Reproduction is viviparous with eggs and sperm broadcast into the water generating pelagic eggs and larvae that can drift in oceanic currents for up to a year before settling out on the bottom. They do not reproduce in waters off California because the temperatures are too cold; instead the reproduction process occurs off the coast of Baja and the larvae drift northward. Juveniles are found in tidal pools and move to deeper waters as they mature. They are long-lived and have lifespans of thirty years.
The California Moray is a resident of Mexican waters of the Pacific but has a limited distribution being found from Magdalena Bay, Baja California Sur, northward along the central and northwest coasts of Baja. The fish pictured below was caught forty miles north of Cabo San Lucas in the Pacific, documenting a significant southerly range extension for this species.
The California Moray can be confused with the Yellow-edged Moray, Gymnothorax flavimarginatus, which is found only at the extreme tip of Baja (yellow margin on tail; larger and serrated teeth on outer row of top jaw).
From a conservation perspective the California Moray is currently considered to be of Least Concern with stable, widely distributed populations. They are very seldom seen by humans. When encountered they are visually most intimidating but are very timid and not harmful and are only known to bite humans on rare occasions. They are caught on occasion by recreational anglers out of heavy rock structure and normally a “catch and release.”