The ribbon eel (Rhinomuraena quaesita) is also known as the leaf-nosed moray eel. With their enlarged nostrils and distinctive coloration they are easily distinguished from any other eel.
Due to their unusual habits and physiology there is some debate as to whether they should be classified as Moray eels. The sexes are very distinctive and the male is pictured above and the female below.
The Ribbon eel is a very distinctive looking eel with their sharp head and enlarged fan like nasal openings and projections on the lower jaw. Once thought to be three separate species, they undergo fairly dramatic colour changes during their life cycle.
The juveniles start off being black with a yellow dorsal fin and unsurprisingly these are the most commonly seen as the numbers are greater. Once they reach a size of approximately 60 cm the black turns to a bright blue colour as pictured in the image below. The nasal area and the ring around the eye take on a bright yellow colour which contrasts attractively with the blue.
At this stage they are sexually mature males. As they grow larger to around 90 cm, so they change colour once again and the entire body is a yellow colour, sometimes with a blueish green tint on the lower body. Female organs develop and at the yellow stage the Ribbon eel is capable of laying eggs. Very unusually the reproductive organs and kidneys on Ribbon eels are behind the anus. This among other physical anomalies has led to calls to reclassify them.
The mouth is long and thin with fine sharp teeth for gripping prey. They usually have a further two rows of teeth running down the middle of the roof of the mouth. These aid in hanging onto prey to prevent it escaping. They do not have pectoral or pelvic fins and the dorsal fin runs the length of the body. Research has indicated that their eyes have adapted to feeding during the day which is unusual for Moray Eels.
IN THE WILD
Ribbon eels are usually seen with their heads protruding from a hole with their body swaying around. They often position themselves in areas where large numbers of cardinal fish or sweepers have congregated for the day. They extend themselves out their hole and sway from side to side, slowly swaying closer to an unsuspecting fish. If one watches them, it seems quite obvious when they have picked a fish out.
They will slowly extend themselves out the hole almost imperceptibly and swing closer and closer to the target fish. At the last second they dart at the fish. From watching these maneuvers they do not have a high success rate. They are however very persistent and do not change their motion much after an unsuccessful strike.
Moray eels have proportionately small circular gills, located on posterior of the mouth and the moray is constantly opening and closing its mouth to facilitate sufficient water flow over its gills. In general the opening and closing of the mouth is not threatening behavior but one should not approach too closely. They will bite if threatened. Being somewhat smaller than most moray eels, the Ribbon Eel will usually retreat into its hole if one approaches too closely.
On very rare occasions one will see a Ribbon eel swimming in the open and this is quite a sight to see. With its long thin body undulating through the water the sight is reminiscent of a gymnast performing with a ribbon. This can be seen in the video below. The specimen in the video is a juvenile with black and yellow coloration.
Some researchers speculate that moray eels contain toxins in their mouths and are poisonous. Based on personal experience and having been bitten by many different species of eels while catching crayfish in Kwa-Zulu Natal, this is not true. Morays secrete mucus over their scale less skin, which in some species contains toxins. They have a thick skin and a large number of cells that secrete mucus epidermis. In Ribbon eels this mucus may assist in holding their burrows together. Very little if anything is known on the toxicity of Ribbon eels but it is unlikely that they will be toxic in any way.
The Ribbon eel is carnivorous, and feed mainly on small fish. Having been in the water in Tanzania after dynamiting has taken place and there have been large numbers of small dead fish floating around, the Ribbon Eel have displayed no interest in these dead fish. Moray Eels usually have relatively poor eye sight and an excellent sense of smell that they use to detect their prey. The Ribbon Eel certainly has better eye sight than most Moray eels and is able to pick relatively small fish out as witnessed personally on many occasions. One can only speculate from their enlarged nostrils, that they too have a good sense of smell that would allow them to catch small fish in low visibility.
Moray eels have a second set of jaws in their throat called pharyngeal jaws, which also have teeth. When feeding, morays latch onto the prey with their outer jaws. They then push their pharyngeal jaws which are set back in the pharanx, forward into the mouth. They then grasp the prey and pull it into the throat and stomach. Moray eels are the only fish that use pharyngeal jaws to capture prey.
Ribbon eels are exploited to some extent for the Marine Aquaria trade but so far there is no evidence of this damaging the population levels.
Ribbon eels are notoriously difficult to keep in aquariums for three reasons. Firstly they do not travel well and become highly stressed. Secondly they do not easily take to prepared foods and prefer live foods and thirdly they are great escape artists and will leave the tank unless it is very tightly sealed. This fish is probably best left in the ocean.
They have been kept with some success in large public aquaria in large tanks.
RIBBON EEL CLASSIFICATION
- The Reef Guide fishes, corals, nudibranchs & other invertebrates: East and South Coasts of Southern Africa by Dennis King & Valda Fraser
- Fishelson, L. Mar. Biol. (1990) 105: 253. https://doi.org/10.1007/BF01344294