Spottail Moray, Gymnothorax equatorialis
The Spottail Moray, Gymnothorax equatorialis, whose common Spanish name is morena cola pintada, 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. Globally, there are one hundred sixteen members in the genus Gymnothorax, eighteen of which are found in Mexican waters, nine in the Atlantic and nine in the Pacific.
The Spottail Morays have stout elongated compressed bodies that taper to a narrow tail with a slender tip. They are dark brown and transition to light tan ventrally. They have very elongated small white spots on their head, which become larger toward the rear of their body. The spots at the base of their tail is the key to identification; they are very elongated, longer than eye diameter, and widely spaced. Their anal fin has a dark black margin. The traditional black spot on the gill covers of many Morays is not readily visible in this species. Their head is rounded with a short blunt snout and large eyes. Their front nostrils have tubes and their rear nostrils are flush with the head profile. They have a large mouth equipped with enlarged “shark-like” teeth that are triangular and curved in shape with serrated rear edges; their teeth are present as a single row on each jaw. Their anal and dorsal fins are very low, covered with skin, and continuous with the caudal fin. Their dorsal fin originates in front of the gill openings. Their tail is approximately half or slightly greater than half the body length. They have no pectoral fins or scales. They are covered with thick yellow mucus, which provides them with protection from abrasion.
The Spottail Morays are found over soft sandy bottoms adjacent to rocky reefs from the intertidal zone to depths of 600 feet. They reach a maximum length of 1.0 meter (2 feet 11 inches) with females being slightly larger than males. 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 open and close their mouth frequently, an action required for respiration. Reproduction is viviparous with eggs and sperm broadcast into the water generating pelagic eggs and larvae that drift in oceanic currents before settling out on the bottom. Each females releases an average of 32,000 eggs per year. They are a poorly studied and poorly documented species and very little is known about their behavior patterns.
In Mexican waters the Spottail Moray are found in all waters of the Pacific with the exception that they are absent from the entire west coast of Baja. However I have collected a fish 40 miles north of Cabo San Lucas, extending the known range for the species, indicating that they can probably be found as far north as Magdalena Bay along the Pacific coast.
The Spottail Moray can be confused with the Finespotted Moray, Gymnothorax dovii (small white spots covering head and body) and the Many-Spotted Moray, Gymnothorax phalarus (deeper tail with round or oval spots that are close together and less than eye diameter) .
The Spottail 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.
Spottail Moray, Gymnothorax equatorialis. Fish caught off Point Palmilla, Baja California Sur, March 2016. Length 40 cm (16 inches); Tail: 53%.