Undulated moray (Gymnothorax undulatus)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Chordata · Class: Teleostei · Order: Anguilliformes · Family: Muraenidae · Genus: Gymnothorax.

Accepted name: Gymnothorax undulatus · Authority: (Lacepède, 1803) · Taxonomic status: accepted · AphiaID: 217508.

Synonyms and superseded combinations recorded for this taxon: Gymnothorax undulates (Lacepède, 1803); Lycodontis undulata (Lacepède, 1803); Lycodontis undulatus (Lacepède, 1803); Muraena cancellata Richardson, 1848; Muraenophis undulata Lacepède, 1803.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=217508 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (FishBase)

Measured values published by FishBase for Gymnothorax undulatus. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Maximum length: 150 cm · Depth range: 0–110 m · Habitat zone: reef-associated · Body shape: eel-like · Vulnerability index: 90 of 100 · Fishery importance: minor commercial · Aquarium trade: commercial.

FishBase notes: A common species on reef flats among rocks, rubble, or debris and also occurs in lagoons and seaward reefs to depths of 26 m or more. Minimum depth reported taken from Ref. 86942. Cavernicolous (Ref. 8593, 58302). Benthic (Ref. 58302). Nocturnal species that feeds on fishes, octopi, and probably crustaceans. Reported to be an aggressive species and prone to bite. Used in Chinese medicine (Ref. 12166).

Source: FishBase species summary (SpecCode 4905) — https://www.fishbase.se/summary/Gymnothorax-undulatus.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

1,859 georeferenced occurrence records for Gymnothorax undulatus are published through GBIF from 61 countries or marine areas. The map above plots 336 distinct locations from a sample of 1,859 records, omitting 70 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: United States of America (464); Australia (208); South Africa (116); Seychelles (109); Maldives (83).

The full country table, WoRMS marine regions and the sampling notes are on this species' Distribution page.

Source: GBIF Occurrence Search (taxonKey 2403755) — https://www.gbif.org/occurrence/search?taxon_key=2403755&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=217508 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Conservation status (IUCN Red List)

The IUCN Red List assesses Gymnothorax undulatus (Lacepède, 1803) as Least Concern (code LC). No trend, population estimate or threat analysis is given here, because none is available from this source without the Red List API; follow the source link for the full assessment, including its date.

Source: IUCN Red List of Threatened Species (taxon 195803) — https://www.iucnredlist.org/species/195803/0; GBIF IUCN Red List category endpoint (taxonKey 2403755) — https://api.gbif.org/v1/species/2403755/iucnRedListCategory. Accessed 2026-09-23.

Description and natural history (Wikipedia)

The undulated moray can easily be identified by its yellow head and brown spots covering its body. It is also lined by white borders forming similar to a chain link. They use their large mouths to pump water to the gills, while the gill cover is a small hole to protect the delicate gills. Like most eels, they lack the pectoral and pelvic fins to make it easier for them to move through the crevices of reefs. Their other fins are fitted with thicker skin to protect from sharp reef. They move in a S-shape to be able to move back and forth to also aid in movement through reefs. Their teeth are shaped to be curved backwards so they can hold onto their prey and easily move the prey backwards for digestion.

Gymnothorax undulatus can be found in the Pacific as well as East Africa. Most of the time they can be found in reefs of lagoons and seawards or in reef-flats. They like to shelter within reefs and can be found from depths of 1 to 50 meters. The undulated moray is nocturnal as they hide in reefs during the day and hunt for food at night.

The undulated eel and several other species of eels (puhi) are featured in many Hawaiian stories as common ʻaumakua, thought to be ancestors protecting families. This eel is known as laumilo or "milo leaf" from the way it swims similar to blown leaves of the milo tree, it itself is considered a guardian for the tree according to the Kumulipo. This eel was also a common form that Kū, the Hawaiian god of war, would take to interact with humans.

For many native Hawaiian communities eels were an important food source and used for special dishes when leaders had special guests, this particular eel is deemed "highly relished".

Source: Wikipedia: Undulated moray — https://en.wikipedia.org/wiki/Undulated_moray (CC BY-SA 4.0). Accessed 2026-09-23.