Ribbon eel
A color-changing moray eel found in Indo-Pacific reefs.
The ribbon eel (Rhinomuraena quaesita), sometimes called the leaf-nosed moray eel or bernis eel, is the sole species in the genus Rhinomuraena and belongs to the moray eel family. It lives in sand burrows and among reefs across the Indo-Pacific Ocean. Though it is usually classified under the family Muraenidae, its unusual traits have led some experts to suggest it deserves its own family, Rhinomuraenidae.
In terms of taxonomy, this eel is the only member of its genus within the subfamily Muraeninae. Its reproductive anatomy sets it apart: while most eels in the family have sex cells that move toward the anus, the ribbon eel’s sex cells travel forward, toward the head. This oddity, likely due to an evolutionary event like peripatric speciation, supports arguments for separating it. Previously, blue ribbon eels were called *R. quaesita* and black ones *R. amboinensis*, but scientists now recognize them as the same species. Its closest known relative is the pink-lipped moray (*Echidna rhodochilus*), which does not group neatly with other *Echidna* species.
Ribbon eels are widespread across tropical parts of the Indian and Pacific Oceans, from East Africa to southern Japan, Australia, and French Polynesia. Divers often spot them in Indonesian waters, where their heads and front bodies poke out from crevices in sandy or rubble areas, such as coral reefs. A slime coat helps them slip through tight spaces. They prefer shallow water, typically between 1 and 57 meters deep.
The species has a long, thin body and a high dorsal fin. Its expanded front nostrils and wide-open jaws make it easy to recognize. With up to 255 vertebrae, it is one of the most slender and elongated eels known. Juveniles and subadults are jet black with a yellow dorsal fin. Adult males turn a vivid blue with a yellow face, while adult females are entirely yellow or yellow with some blue toward the rear. No other moray eel changes color alongside a sex change. Blue males measure 65 to 94 cm (26 to 37 in), while larger yellow females can reach 130 cm (51 in). The larva is a large, greenish leptocephalus.
Despite its dramatic color shifts, color likely plays little role in mating because ribbon eels are colorblind—they have only one of the two photoreceptor cells needed to see color. In the wild, they can live up to twenty years. They are diurnal, active during the day.
Quick Facts
- Taxon
- Rhinomuraena quaesita
Facts from the source article.
Lore & Background
The ribbon eel is the only species in its genus, Rhinomuraena, in the subfamily Muraeninae of the moray eel family. Its unique morphology, such as its gonad structure and function, are not shared with many of the other major genera in the family and provided evidence for separation. Typically, eels of the family urogenital system follow a posterior pattern toward the anus, but the Rhinomuraena system has its sex cells move anteriorly. Previously, R. quaesita was used to identify blue ribbon eels and R. amboinensis for black ribbon eels, but these are now recognized as the same species. Its closest known relative is the pink-lipped moray (Echidna rhodochilus), which does not form a monophyletic group with the other Echidna species.
Ribbon eels are characterized by a long, thin body and high dorsal fins, with expanded anterior nostrils and wide-open jaws. They can have up to 255 vertebrae. In juvenile and subadult stages, they appear jet black with a yellow dorsal fin. Adult males are vibrant blue with a yellow face; adult females are entirely yellow or yellow with some blue posteriorly. Color change related to sex change is not known from any other moray eel species. The larva is a large, greenish leptocephalus.
It is presumed that coloring does not play a significant role in mating because the eels are colorblind. Ribbon eels are diurnal and generally considered protandric hermaphrodites (male to female transformation). When necessary, males will develop reproductive organs, lay eggs, and then die within about a month.
Reader's Guide
The ribbon eel is notable for its unique morphology and reproductive biology, which set it apart from other moray eels. Its anteriorly directed sex cells and protandric hermaphroditism are distinctive features that have led some taxonomists to propose a separate family, Rhinomuraenidae. The species undergoes dramatic color changes correlated with sex change, a phenomenon not observed in any other moray eel. Despite being colorblind, the eel's vibrant blue and yellow adult coloration is a hallmark for divers in the Indo-Pacific. The ribbon eel is widely distributed and common, listed as Least Concern on the IUCN Red List as of 2009. However, it faces potential threats from coral bleaching, habitat damage due to climate change and pollution, and overfishing. In captivity, most ribbon eels do not live longer than a year, often refusing to eat after capture, though public aquaria have reported rare spawning events. Its popularity in the aquarium trade continues, but the species remains widespread and not considered threatened.
Did You Know?
- The ribbon eel is the only member of the genus Rhinomuraena.
- Its gonad structure moves sex cells anteriorly, unlike most other moray eels.
- Adult males are blue and yellow, while females are entirely yellow or yellow with blue posteriorly.
- Ribbon eels are colorblind, possessing only one of the two photoreceptor cells needed to see colors.
Frequently Asked Questions
What is a ribbon eel?
The ribbon eel (Rhinomuraena quaesita) is a color-shifting moray eel found across Indo-Pacific reefs, also known by the nicknames leaf-nosed moray and bernis eel. It is the sole species in the genus Rhinomuraena.
How big does a ribbon eel get?
Females can reach up to 130 cm (51 in) while males max out at 94 cm (37 in). Their elongated bodies contain as many as 255 vertebrae.
Where do ribbon eels live?
They dig burrows in sand and shelter among reef structures throughout the Indo-Pacific Ocean. Their depth range spans from just 1 meter down to 57 meters.
Why is the ribbon eel taxonomically unusual?
Its reproductive anatomy departs from the norm seen in other muraenids, with sex cells that develop differently from the typical pattern. This has prompted some experts to argue it warrants its own family, Rhinomuraenidae, rather than staying under Muraenidae.
How long do ribbon eels live in the wild?
In their natural habitat, ribbon eels can live up to twenty years.
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