electric eel: see electric fish.

eel, electric: see electric fish.

eel, common name for any fish of the 10 families constituting the order Anguilliformes, and characterized by a long snakelike body covered with minute scales embedded in the skin. Eels lack the hind pair of fins, adapting them for wriggling in the mud and through the crevices of reefs and rocky shores. Most species are marine; the largest and most diverse group are the morays, family Muraenidae, sharp-toothed and vicious. Moray eels have a highly developed second set of jaws (pharyngeal jaws) that hold and pull prey into the throat after the main jaws snare it. The common freshwater eel, Anguilla rostrata, of the family Anguillidae, is found in the Atlantic coastal regions of Europe, in the Mediterranean area, and in North America E of the Rockies. Several other freshwater species are native to Asia. The mature European eel migrates 3,000 to 4,000 mi (4,828-6,437 km) to its spawning ground in the deep sea SW of Bermuda, a journey lasting several months. There it reproduces and then dies. The young hatch as transparent ribbonlike larvae that drift north and east on ocean currents for three years before entering a river; they then develop into elvers, tiny versions of the adult eel. The American eel follows the same pattern, except that the young require only one year to return to freshwater. Once there, the developing elvers feed voraciously on dead and living animals, even traveling over short stretches of land in search of frogs and lizards. They hunt at night and rest by day. The male, which attains a length of 2 ft (61 cm), remains at the river's mouth, while the female (4 ft/122 cm) swims upstream, staying there from 5 to 20 years. When the eels are sexually mature their enormous appetite wanes, and they do not eat during migration to the spawning ground. The oily flesh is regarded by some as a delicacy; the skin was formerly used as leather. Eels are classified in the phylum Chordata, subphylum Vertebrata, class Osteichthyes, order Anguilliformes.

Congo eel: see salamander.

Any of about 30 species of primitive jawless fishes in two families of the class Agnatha. The Myxinidae are found in every ocean; the Eptatretidae are found everywhere but the North Atlantic. Hagfishes are eel-like, scaleless, and soft-skinned and have paired thick barbels on the end of the snout. Species grow to 16–32 in. (40–80 cm) long. They have a cartilaginous skeleton. The mouth is a slitlike, sucking opening with horny teeth. Found in cold seawater, to depths of over 4,000 ft (1,200 m), they habitually lie buried in burrows on soft bottoms. They eat invertebrates and dead or crippled fishes, and may bore their way into the bodies of fish caught on lines or in nets and eat the fish from the inside. They secrete extraordinary amounts of slime when handled. Seealso lamprey.

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Any of about 80 species (family Muraenidae) of shallow-water eels inhabiting all tropical and subtropical seas. They live among reefs and rocks and hide in crevices. Their skin is thick, smooth, scaleless, and usually vividly marked or coloured. Most species lack pectoral fins. Morays have a wide mouth and strong, sharp teeth for seizing and holding prey (chiefly other fishes). They attack humans only when disturbed. Most species are less than 5 ft (1.5 m) long, but Thyrsoidea macrurus, of the Pacific Ocean, may grow to more than 11 ft (3.5 m). Morays are sometimes eaten, but their flesh may be toxic and can cause illness or death if consumed.

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Eel-shaped South American fish (Electrophorus electricus) capable of producing an electric shock strong enough to stun a human. The electric eel (not a true eel) is a sluggish inhabitant of slow freshwater, surfacing periodically to gulp air. Long, cylindrical, scaleless, and gray-brown, it sometimes reaches a length of 9 ft (2.75 m) and a weight of 49 lbs (22 kg). The tail region, bordered below by a long anal fin that the fish undulates to move about, contains the electric organs. The shock (up to 650 volts discharged at will) is used mainly to immobilize fish and other prey.

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Any of more than 500 fish species (order Anguilliformes) that are slender, elongated, and usually scaleless, with long dorsal and anal fins that are continuous around the tail tip. Eels are found in all seas, from coastal regions to the mid-depths. Freshwater eels are active, predaceous fish with small embedded scales; they grow to maturity in freshwater and return to the sea, where they spawn and die. The transparent young drift to the coast and make their way upstream. Freshwater eels, considered valuable food fish, include species ranging from 4 in. (10 cm) to about 11.5 ft (3.5 m) long. Seealso moray.

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Any of about 100 species of marine eels (family Congridae) with no scales, a large head, large gill slits, a wide mouth, and strong teeth. Conger eels are usually grayish to blackish, with a paler belly and black-edged fins. Found in all oceans, sometimes in deep water, they may grow about 6 ft (1.8 m) long. Conger eels are carnivores. Many species, such as the European conger (Conger conger), are valued as food. The American conger, or sea eel (C. oceanicus), is a fierce game fish.

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