Undulated moray (Gymnothorax undulatus)

Also known as: Common Hawaiian moray, leopard moray
Synonyms: Lycodontis undulate, Lycodontis undulates, Muraena cancellata, Muraenophis undulata
GenusGymnothorax (1)
SizeLength: up to 150 cm (2)

The undulated moray has yet to be classified by the IUCN.

The undulated moray (Gymnothorax undulatus) is a distinctive moray eel, taking its name from the pattern of light undulating lines that form a faint net-pattern along its long, sinuous body (3) (4). An otherwise dark green to black-brown eel, the head is bright yellow in colour and a conspicuous yellow line runs along the top of the dorsal fin. A thin membrane covers all of the fins and runs around the body from the dorsal fin, round the tail fin to the anal fin (5). As a voracious predator, the undulated moray has large, elongated jaws, with the lower jaw being slightly hooked (3), and the mouth is armed with rows of long, thin, fang-like teeth (6). Like other moray eels, the undulated moray does not have scales, and so to protect itself from parasites and scrapes, it secretes a protective layer of mucus over the thick, muscular body (7).

Occurring in coastal areas and around islands in the Indian Ocean and western, central and eastern Pacific Ocean, the greatest density of undulated morays is found throughout south-east Asia, from Indonesia and the Philippines southwards to northern Australia (2).

Commonly found on reef flats and in lagoons, the undulated moray hides amongst rocks, rubble or debris down to depths of 30 metres (2).

The undulated moray is a nocturnal species that uses its keen sense of smell to actively and aggressively hunt for fish, octopus and crustaceans, consuming almost anything that will fit in its mouth (2) (3) (6). When prey is captured, it uses a specialised second set of jaws within the throat to grasp onto the prey and drag it back into the throat (8).

 Not much is known about the biology of the undulated moray, but in other species of moray eel, the male begins courtship by displaying to a female, before entwining around the female’s body (7). Once pair formation is complete, the female spawns large numbers of heavily-yolked eggs, which are fertilised externally by the male. Small, ribbon-shaped larvae subsequently emerge from the eggs to drift passively in ocean currents as part of the zooplankton community, before growing large enough to establish a territory on a reef (7) (9).

The undulated moray does not appear to be under any immediate threat of extinction, although it is occasionally targeted by commercial fisheries and is also captured for aquariums or use in traditional Chinese ‘medicine’ (2).

There are currently no known conservation plans targeting the undulated moray.

For more information on the World Fisheries Trust, see:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:

  1. ITIS (October, 2010)
  2. FishBase - Undulated moray (October, 2010)
  3. Sadovy, Y. and Cornish, A.S. (2000) Reef Fishes of Hong Kong. Hong Kong University Press, Hong Kong.
  4. King, D. and Fraser, V. (2001) More Reef Fishes and Nudibranchs. Struik Publishers, Cape Town, South Africa.
  5. Allen, G.R. and Robertson, D.R. (1994) Fishes of the Tropical Eastern Pacific. Crawford House Press Pty Ltd, Bathurst, Australia.
  6. Bohlke, E.B. and Randall, J.E. (2000) A review of the moray eels (Angulliformes: Muraenidae) of the Hawaiian Islands, with descriptions of two new species. Proceedings of The Academy of Natural Sciences, 150: 203-278.
  7. Shedd Aquarium (October, 2010)
  8. Mehta, R.S. and Wainwright, P.C. (2007) Raptorial jaws in the throat help moray eels swallow large prey. Nature, 449: 79-82.
  9. Burton, M. and Burton, R. (2002) The International Wildlife Encyclopedia: Volume 1. Marshall Cavendish Corporation, New York, USA.