California Moray

California Moray, Gymnothorax mordax

The California Moray, Gymnothorax mordax, whose common Spanish name is morena de California, is a member of the Muraenidae or Moray and Snake Moray Eels Family, known collectively as morenas in Mexico. There are one hundred sixteen global members of the Gymnothorax Genus, of which eighteen are found in Mexican waters, nine in the Atlantic and nine in the Pacific.

The California Moray has a stout elongated body that tapers gradually to a rounded tail. They are light yellow brown in color with finely irregular dark brown spots or mottling. They quickly fade to a uniform gray-brown upon death. They have a large, a small black spot covering the gill openings. The head is large and bulbous with small eyes, tube nostrils, a large mouth equipped with visible canine teeth and prominent jaws that have two rows (with the outer row being smaller than the inner row) of pointed , conical, not serrated teeth and the lower jaw also has five rows of teeth at the front. The anal fin which originates before mid-body, and the dorsal fin, which originates before the gill openings, are covered with skin. The tail is approximately 50% of the body length. They do not have pectoral or pelvic fins, gill covers or scales. They are covered with a thick yellow mucus that provides them with protection from abrasion.

The California Moray is a common inhabitant of shallow reef areas that are found within cracks and crevices in the subtidal zone to depths of 130 feet. They reach a maximum length of 152 cm (60 inches). During the day they have only their heads protruding. The body shape and lack of fins, scales, or gill covers allows this species to move quickly in and out of rocky crevices, As such they are 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 are also known for its unique adaptation, a second set of jaws inside its throat that spring forward to help it to swallow food. Octupus is a favorite food, but octopus ink fowls the eels smell for up to two hours. They open and close their mouths frequently, an action that is required for respiration. They have a symbiotic relationship with the Red Rock Shrimp, Lysmata californica, that habitat the same burrows and serve as cleaners removing food and parasites; in return the California Moray’s provide protection to the shrimp. Reproduction is viviparous with eggs and sperm broadcast into the water generating pelagic eggs and larvae that may drift in oceanic currents for up to a year before settling out on the bottom. It is believed that the California Morays do not reproduce in waters off California because the water temperatures are too cold; instead they hatch off Baja and drift north as larvae. Juveniles are found in tidal pools and as they mature they move to deeper waters. They are long lived with life spans of up to 30 years. In Mexican waters the California Moray Eel has a limited distribution being found from the California Boarder to Magdalena Bay. The fish pictured below, caught 40 miles north of Cabo San Lucas in the Pacific, documents a significant southerly range extension for this species.

The California Moray can be confused with the Yellow Margin Moray, Gymnothorax flavimarginatus (found only on the extreme tip of the Baja, yellow margin on the tail; outer row of teeth on the top jaw are larger and serrated).

The California Morays are of limited interest to most fishermen and are normally a “catch and release.” Visually they are most intimidating but they are very timid and are not harmful and bites of humans are uncommon.

F546-California Moray (1)

F546-California Moray (2)

California Moray Eel, Gymnothorax mordax: Fish provided by commercial fishermen of the greater Los Cabos area, Baja California Sur, September 2009. Length: 94 cm (37 inches). Tail: 49%.
California Moray Eel, Gymnothorax mordax: Fish provided by commercial fishermen of the greater Los Cabos area, Baja California Sur, September 2009. Length: 94 cm (37 inches). Tail: 49%.