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. Globally, there are 116 members in the genus Gymnothorax, of which 18 are found in Mexican waters, nine in the Atlantic and nine in the Pacific.
The California Morays have stout elongated bodies that taper 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 have no pectoral or pelvic fins, gill covers or scales. They are covered with thick yellow mucus, which provides them with protection from abrasion.
The California Morays are common inhabitants of shallow reef areas found within cracks and crevices in the subtidal zone at depths up to 130 feet. They reach a maximum length of 1.52 meters (5 feet). Only their head protrudes during the day. Their body shape and 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, consuming small fish and invertebrates including crab, 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 Morays provide protection to this shrimp species. 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. It is believed that they do not reproduce in waters off California because the temperatures are too cold; instead they hatch off the coast of Baja and drift north as larvae. Juveniles are found in tidal pools and move to deeper waters as they mature. They are long-lived and have a lifespan of up to 30 years. They have a limited distribution in Mexican waters, being found from the California border to Magdalena Bay. The fish pictured below was caught 40 miles north of Cabo San Lucas in the Pacific, thus 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).
The California Morays are of limited interest to most and normally a “catch and release”. Visually they are most intimidating but are very timid and not harmful. They seldom bite humans.