Undulated Moray, Gymnothorax undulatus
Undulated Moray, Gymnothorax undulatus. Fish caught from coastal waters off Kona, Hawaii, July 2017. Length: 79 cm (2 feet 7 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).
Undulated Moray, Gymnothorax undulatus. Fish caught from within the marina of He’eia Kai Pier, Kaneohe, Oahu, Hawaii, February 2016. Length: 81 cm (2 feet 8 inches). Catch, photograph and identification courtesy of Kenneth Tse, Toronto, Ontario, Canada.
Undulated Moray, Gymnothorax undulatus. Fish caught off the Kona Pier, Kona, Hawaii, March 2021. Length: 83 cm (2 feet 9 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.
Undulated Moray, Gymnothorax undulatus. Fish caught off the Kona Pier, Kona, Hawaii, March 2021. Length: 85 cm (2 feet 10 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.
The Undulated Moray, Gymnothorax undulatus, is a member of the Moray and Snake Eel or Muraenidae Family, that is also known as the Greenhead Moray and in Mexico as morena ondulada. 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 Undulated Moray has an elongated muscular compressed body that tapers gradually to a pointed tail. They are a pale yellowish color but also can be brown, gray or white. The head is heavily mottled with dark spots, the dorsal section being greenish yellow in most fish. The body is covered with dark blotches that are separated by diffuse yellow lines forming a chain-like pattern. This pattern is more pronounced in juveniles than in adults which are irregularly mottled. Their snout is often yellow. Their head is pointed, the mouth equipped with teeth pointed and smooth, with 3 rows on the front of the top jaw with 3 long fangs, and 1 row at the sides of the top jaw. The anal and dorsal fins, originating in front of the gill openings, are covered with skin, but clearly evident. The tail is approximately 50% of total length. They do not have pectoral fins, pelvic fins, gill covers or scales. They are covered with thick yellow mucus, which provides them with protection from abrasion.
The Undulated Moray is a common inhabitant of shallow rocky reef and rubble areas and are found within caves, cracks, and crevices in the subtidal zone and in lagoons at depths up to 100 m (330 feet). They reach a maximum of 1.50 m (5 feet 11 inches) in length. They are found as solitary individuals that 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. They consume crabs, fish, octopus, and shrimp. Reproduction is viviparous with each female releasing large numbers of heavily-yoked eggs which are then fertilized externally by the males. Small, ribbon-shaped pelagic larvae eventually emerge from the eggs. The Undulated Moray is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
The Undulated Moray is a resident of Mexican waters of the Pacific but has an exceedingly limited distribution being found only within the coastal waters of the Revillagigedo Islands.
The Undulated Moray, due to its unique coloration, is a straightforward identification that cannot be confused with any other species.
From a conservation perspective, the Undulated Moray is currently considered to be of Least Concern with stable, widely distributed populations. They are caught commercially with nets in certain parts of their range primarily by artisanal fishermen and utilized for human consumption. They are known to contain ciguatoxin. When encountered they are visually most intimidating, aggressive, and are known to bite humans. They are utilized in traditional Chinese Medicine and by the aquarium trade but only at a small level.