Undulated moray (Gymnothorax undulatus)

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Undulated moray fact file

Undulated moray description

GenusGymnothorax (1)

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).

Also known as
Common Hawaiian moray, leopard moray.
Lycodontis undulate, Lycodontis undulates, Muraena cancellata, Muraenophis undulata.
Length: up to 150 cm (2)

Undulated moray biology

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).


Undulated moray range

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).


Undulated moray habitat

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


Undulated moray status

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


Undulated moray threats

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).


Undulated moray conservation

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

Environment Agency - Abu Dhabi is a principal sponsor of ARKive. EAD is working to protect and conserve the environment as well as promoting sustainable development in the Emirate of Abu Dhabi.
View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

For more information on the World Fisheries Trust, see:



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Anal fin
In fish, an unpaired fin on the under surface of a fish, behind the anus.
Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.
Dorsal fin
The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans.
The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
Stage in an animal’s lifecycle after it hatches from the egg. Larvae are typically very different in appearance to adults; they are able to feed and move around but usually are unable to reproduce.
Active at night.
An organism that derives its food from, and lives in or on, another living organism at the host’s expense.
An area occupied and defended by an animal, a pair of animals or a colony.
Tiny aquatic animals that drift with currents or swim weakly in water.


  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.

Image credit

Undulated moray portrait  
Undulated moray portrait

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