#anguilliformes

European Eel (Anguilla anguilla), family Anguillidae, order Angulliformes, River Severn, England, UK

CRITICALLY ENDANGERED.

Gymnothorax undulatus

Undulated Moray

Image source

Status: Least concern

The Riveting Ribbon Eel

The ribbon eel, also known as the blue ribbon eel, the leaf-nosed moray eel or the bernis eel (Rhinomuraena quaesita) is a species of moray eel distributed throughout the warm waters of the Indian and Pacific Ocean. They are often found in warm lagoons and sandy or rocky areas near coral reefs. They are seldom seen at depths greater than 57 m (187 ft).

Leaf-nosed moray eels spend most of their time in burrows or rocky crevices, waiting for small fish and crustaceans to come close enough to ambush. They are active mainly during the day, but even then they don't often venture out into the open unless they have to. R. quaesita has a few natural predators, including other moray eels and groupers. Unlike their more famous cousins the giant moray, they don't have a very strong bite, so they avoid being eaten mainly by hiding. Thanks to their unique, tube-shaped nostrils they also have excellent senses of smell.

Blue ribbon eels are characterised by their extremely long, thin bodies. Adults have up to 255 vertebrae, making them one of the longest known eels in the world. Males range from 65 to 94 cm (26 to 37 in) in length, while females can reach up to 130 cm (51 in). Males and females are also differentiated by their color; males are striped blue and yellow, while females are completely yellow from head to tail.

R. quaesita are protandrous, which means they all intially develop as male, and transition to female as they get older and larger- typically starting their transition around 1 m (39 in) in length. Little is known about when they reproduce, but when males and females do decide to mate they release sperm and eggs into the water where they fertilize. The females will only do this once, and they die within a month of reproduction. The larvae drift in the currents until they settle on the ocean bed and develop into black juveniles. It can take several years for them to become fully mature, and adults in the wild may live up to 20 years.

Conservation status: Ribbon eels are considered Least Concern by the IUCN. Those that live near coral reefs may be threatened by coral bleaching and damage. Capture for the pet trade is also a threat, as those held in captivity tend to die quickly and breeding is difficult.

Photos

Erik Schlögl

Lawrence T

Red Sea garden eels (Gorgasia sillneri) in Egypt

(Sources - 1, 2, 3, 4)

Order: Anguilliformes

Common Name: “eels”

Families: 21 - Chlopsidae (“false morays”), Protanguillidae (“Palauan Primitive Cave Eel”), Synaphobranchidae (“cutthroat eels”), Moringuidae (“spaghetti eels”), Anguillidae (“freshwater eels”), Nemichthyidae (“snipe eels”), Serrivomeridae (“sawtooth eels”), Cyematidae (“Arrow Eel”), Monognathidae (“onejaw eels”), Neocyematidae (“orange bobtail eels”), Eurypharyngidae (“Pelican Eel”), Saccopharyngidae (“gulper eels”), Heterenchelyidae (“mud eels”), Myrocongridae (“thin eels”), Muraenidae (“moray eels”), Colocongridae (“worm eels”), Derichthyidae (“longneck eels”), Ophichthidae (“snake eels”), Muraenesocidae (“pike congers”), Nettastomatidae (“duckbill eels”), and Congridae (“conger eels” and “garden eels”)

Anatomy: greatly elongated body; no pelvic fins, many species also lack pectoral fins; the dorsal and anal fins are fused with the caudal fin, forming a single ribbon running along the length of the animal; leptocephalic (flat and transparent) larvae which metamorphose into “glass eels”, and then “elvers”, before finally seeking out their juvenile and adult habitats

Diet: fish, crustaceans, cephalopods, frogs, etc.; larvae are detritivores

Habitat/Range: in oceans worldwide, burrowed into sand, mud, or amongst rocks; most are marine, but some spend part or all of their lives in freshwater

Evolved in: Late Cretaceous

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