Eels (Anguilliformes; ) are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators. The term "eel" is also used for some other similarly shaped fish, such as electric eels and spiny eels, but these are not members of the Anguilliformes order.
Eels are elongated fish, ranging in length from 5 centimetres (2.0 in) in the one-jawed eel (Monognathus ahlstromi) to 4 metres (13 ft) in the slender giant moray.[2] Adults range in weight from 30 grams to well over 25 kilograms. They possess no pelvic fins, and many species also lack pectoral fins. The dorsal and anal fins are fused with the caudal or tail fin, forming a single ribbon running along much of the length of the animal.[1] Most eels live in
the shallow waters of the ocean and burrow into sand, mud, or amongst rocks. A majority of eel species are nocturnal, and thus are rarely seen. Sometimes, they are seen living together in holes, or "eel pits". Some species of eels also live in deeper water on the continental shelves and over the slopes deep as 4,000 metres (13,000 ft). Only members of the Anguillidae family regularly inhabit fresh water, but they too return to the sea to breed.[3]
Eels begin life as flat and transparent larvae, or leptocephali. Eel larvae drift in the surface waters of the sea feeding on marine snow, small particles that float in the water. Eel larvae then metamorphose into glass eels and then become elvers before finally seeking out their juvenile and adult habitats.[2]
This classification follows FishBase in dividing the eels into fifteen families. Additional families that are
included in other classifications (notably ITIS and Systema Naturae 2000) are noted below the family with which they are synomized in the Fish Base system.
The origin of the fresh water species has been problematic. Genomic studies indicate that they are a monophyletic group which originated among the deep-sea eels.[4]
Including Dysommidae, Nettodaridae, and Simenchelyidae
In some classifications the family Cyematidae of bobtail snipe eels is included in the Anguilliformes, but in the FishBase system that family is included in the order Saccopharyngiformes.
The electric eel of South America is not a true eel, but is more closely related to the Carp and catfishes.
Unagi - broiled (kabayaki) eel on rice,
served in a lacquered meal box
Eel trap in Denmark around 1900
Special boats to transport live eels Comacchio
Freshwater eels
(unagi) and marine eels (conger eel, anago) are commonly used in Japanese cuisine; foods such as Unadon and Unajuu are popular but expensive. Eels are also very popular in Chinese cuisine, and are prepared in many different ways. Hong Kong eel prices have often reached 1000 HKD per kilogram, and once exceeded 5000 HKD per kilogram. Eel is also popular in Korean cuisine and is seen as a source of stamina for men.[citation needed] The European eel and other freshwater eels are eaten in Europe, the United States, and other places. A traditional east London food is jellied eels, although their demand has significantly declined since World War II. The Basque delicacy angulas consists of deep-fried elver (young eels); elver eels usually reach prices of up to 1000 euro per kilogram.[5] New Zealand longfin eel is a traditional Maori
food in New Zealand. In Italian cuisine eels from the Valli di Comacchio, a swampy zone along the Adriatic coast, are specially prized along with freshwater eels of Bolsena Lake. In northern Germany, The Netherlands, the Czech republic, Poland, Denmark and Sweden, smoked eel is considered a delicacy.
Fishermen consumed elvers as a cheap dish, but environmental changes have reduced eel populations. They are now considered a delicacy and are priced at up to ?700 per kg in the United Kingdom.[citation needed]
Eels, particularly the Moray eel, are popular among marine aquarists.
Eel blood is toxic to humans[6] and other mammals[7][8][9], but both cooking and the digestive process destroy the toxic protein. The toxin derived from eel blood serum was used by Charles Richet in his Nobel winning research which discovered anaphylaxis (by injecting it into dogs and observing the effect).
Eelskin leather is highly prized. It is very smooth and exceptionally strong. However, it does not come from eels. It comes from the Pacific Hagfish, a jawless fish which is also known as the slime eel.[10][11]
In 2010, Greenpeace International has added the European eel, Japanese eel and American eel to its seafood red
list."The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."[12]
The English name eel descends from Old English ?l, Common Germanic *?laz. Also from the common Germanic are German Aal, Middle Dutch ael, Old High German ?l, Old Norse ?ll. Katz (1998) identifies a number of Indo-European cognates, among
them the second part of the Latin name of
the eels, anguilla, which is attested in its simplex form illa in a glossary only, and likewise the Greek word for "eel", egkhelys, the second part being attested in Hesychius as elyes.[13] The first compound member, anguis "snake", is cognate to other Indo-European words for "snake", cf. Old Irish escung "eel", Old High German unc "snake", Lithuanian ang?s, Greek ophis, okhis, Vedic Sanskrit ?hi, Avestan a?i, Armenian auj, i?, Old Church Slavonic *o??, all from Proto-Indo-European *oguhis, eguhis. The word also appears in Old English igil "hedgehog" (named as the "snake eater"), and perhaps in the egi- of Old High German egidehsa "wall lizard". The name of Bellerophon (?e??e??f??t??, attested in a variant ???e??f??t?? in Eustathius of Thessalonica) according to this theory
is also related, translating to "the slayer of the serpent" (ahih?n), the e??e??- being an adjective for a lost e???- "snake", directly comparable to Hittite ellu-essar- "snake pit". This myth likely came to Greece via Anatolia, and in the Hittite version, the dragon is called Illuyanka, the illuy- part being cognate to the illa word, and the -anka part being cognate to the angu word for "snake". As designations for "snake" (and similar shaped animals) are often liable to taboo in many Indo-European and non-Indo-European languages, no unambiguous Proto-Indo-European form for the eel word can thus be reconstructed, it could have been *el(l)-u-, *el(l)-o- or similar.
A famous attraction on the French Polynesian island of Huahine (part of the Society Islands) is the bridge across a stream hosting 3?6-foot (0.91?1.8 m) long eels, deemed sacred by lo
cal culture.
Including Dysommidae, Nettodaridae, and Simenchelyidae
In some classifications the family Cyematidae of bobtail snipe eels is included in the Anguilliformes, but in the FishBase system that family is included in the order Saccopharyngiformes.
The electric eel of South America is not a true eel, but is more closely related to the Carp and catfishes.
Unagi - broiled (kabayaki) eel on rice,
served in a lacquered meal box
Eel trap in Denmark around 1900
Special boats to transport live eels Comacchio
Freshwater eels
(unagi) and marine eels (conger eel, anago) are commonly used in Japanese cuisine; foods such as Unadon and Unajuu are popular but expensive. Eels are also very popular in Chinese cuisine, and are prepared in many different ways. Hong Kong eel prices have often reached 1000 HKD per kilogram, and once exceeded 5000 HKD per kilogram. Eel is also popular in Korean cuisine and is seen as a source of stamina for men.[citation needed] The European eel and other freshwater eels are eaten in Europe, the United States, and other places. A traditional east London food is jellied eels, although their demand has significantly declined since World War II. The Basque delicacy angulas consists of deep-fried elver (young eels); elver eels usually reach prices of up to 1000 euro per kilogram.[5] New Zealand longfin eel is a traditional Maori
food in New Zealand. In Italian cuisine eels from the Valli di Comacchio, a swampy zone along the Adriatic coast, are specially prized along with freshwater eels of Bolsena Lake. In northern Germany, The Netherlands, the Czech republic, Poland, Denmark and Sweden, smoked eel is considered a delicacy.
Fishermen consumed elvers as a cheap dish, but environmental changes have reduced eel populations. They are now considered a delicacy and are priced at up to ?700 per kg in the United Kingdom.[citation needed]
Eels, particularly the Moray eel, are popular among marine aquarists.
Eel blood is toxic to humans[6] and other mammals[7][8][9], but both cooking and the digestive process destroy the toxic protein. The toxin derived from eel blood serum was used by Charles Richet in his Nobel winning research which discovered anaphylaxis (by injecting it into dogs and observing the effect).
Eelskin leather is highly prized. It is very smooth and exceptionally strong. However, it does not come from eels. It comes from the Pacific Hagfish, a jawless fish which is also known as the slime eel.[10][11]
In 2010, Greenpeace International has added the European eel, Japanese eel and American eel to its seafood red
list."The Greenpeace International seafood red list is a list of fish that are commonly sold in supermarkets around the world, and which have a very high risk of being sourced from unsustainable fisheries."[12]
The English name eel descends from Old English ?l, Common Germanic *?laz. Also from the common Germanic are German Aal, Middle Dutch ael, Old High German ?l, Old Norse ?ll. Katz (1998) identifies a number of Indo-European cognates, among
them the second part of the Latin name of
the eels, anguilla, which is attested in its simplex form illa in a glossary only, and likewise the Greek word for "eel", egkhelys, the second part being attested in Hesychius as elyes.[13] The first compound member, anguis "snake", is cognate to other Indo-European words for "snake", cf. Old Irish escung "eel", Old High German unc "snake", Lithuanian ang?s, Greek ophis, okhis, Vedic Sanskrit ?hi, Avestan a?i, Armenian auj, i?, Old Church Slavonic *o??, all from Proto-Indo-European *oguhis, eguhis. The word also appears in Old English igil "hedgehog" (named as the "snake eater"), and perhaps in the egi- of Old High German egidehsa "wall lizard". The name of Bellerophon (?e??e??f??t??, attested in a variant ???e??f??t?? in Eustathius of Thessalonica) according to this theory
is also related, translating to "the slayer of the serpent" (ahih?n), the e??e??- being an adjective for a lost e???- "snake", directly comparable to Hittite ellu-essar- "snake pit". This myth likely came to Greece via Anatolia, and in the Hittite version, the dragon is called Illuyanka, the illuy- part being cognate to the illa word, and the -anka part being cognate to the angu word for "snake". As designations for "snake" (and similar shaped animals) are often liable to taboo in many Indo-European and non-Indo-European languages, no unambiguous Proto-Indo-European form for the eel word can thus be reconstructed, it could have been *el(l)-u-, *el(l)-o- or similar.
A famous attraction on the French Polynesian island of Huahine (part of the Society Islands) is the bridge across a stream hosting 3?6-foot (0.91?1.8 m) long eels, deemed sacred by lo
cal culture.
^ "Poison in the Blood of the Eel", New York Times, 9 April 1899, viewed at [2], accessed 22 January 2010
^ "The plight of the eel", BBC online, as seen at [3], accessed 22 January 2010, mentions that "Only 0.1ml/kg is enough to kill small mammals, such as a rabbit..."
^ "Blood serum of the eel." M. Sato. Nippon Biseibutsugakukai Zasshi (1917), 5 (No. 35), From: Abstracts Bact. 1, 474 (1917)
^ "Hemolytic and toxic properties of certain serums." Wm. J. Keffer, Albert E. Welsh. Mendel Bulletin (1936), 8 76-80.
^ Katz, J. (1998).
"How to be a Dragon in Indo-European: Hittite illuyankas and its Linguistic and Cultural Congeners in Latin, Greek, and Germanic". In Jasanoff; Melchert; Oliver. M?r Curad. Studies in Honor of Calvert Watkins. Innsbruck. pp. 317?334. ISBN 3851246675.
Anguillidae is a family of fishes that contains the freshwater eels. There are 19 species and 6 subspecies in this family, all in genus Anguilla. They are catadromous, meaning they spend their lives in freshwater rivers, lakes, or estuaries and return to the ocean to spawn. The young eel larvae, called leptocephali, live only in the ocean and consume small particles called marine snow. They grow larger in size, and in their next growth stage they are called glass eels. At this stage they enter estuaries and when they become pigmented they are known as elvers. Elvers travel upstream in freshwater rivers where they grow to adulthood. Some details of eel reproduction are as yet unknown, and the discovery of the spawning area of the American and European eels in the Sargasso Sea is one of the more famous anecdotes in the history of Ichthyology (see Eel life history). The spawning areas of some other anguillid eels, such as the Japanese eel, and
the giant mottled eel were also discovered recently in the western North Pacific Ocean. [more]
The Chlopsidae, or false morays, are a family of eels found in coral reefs worldwide. As their name suggests, they somewhat resemble moray eels in appearance. However, they are smaller than true morays, ranging from 11 centimetres (4.3 in) to 42 centimetres (17 in) in length. [more]
Colocongridae
The Colocongridae, the Worm eels or Short-tail eels are a family of eels, containing a single genus, Coloconger. [more]
Congridae
Congridae is the family of conger and garden eels. Congers are valuable and often large food fishes, while garden eels live in colonies, all protruding from the sea floor after the manner of plants in a garden (thus the name). The family includes over 180 species in 32 genera. [more]
Derichthyidae
Longneck eels or neck eels are a family, Derichthyidae, of eels. They are pelagic fishes, found in the middle and depths of most oceans. The name comes from Greek deres meaning "neck" and ichthys meaning "fish". [more]
Heterenchelyidae
The Heterenchelyidae or Mud eels are a small family of eels native to the Atlantic, Mediterranean, and eastern Pacific. [more]
The Moringuidae is a small family of eels. They are commonly known as spaghetti eels or worm eels, although the latter name is also shared with other families of eel. [more]
Muraenesocidae
The Muraenesocidae, or pike congers, are a small family of marine eels found worldwide in tropical and subtropical seas. Some species are known to enter brackish water. [more]
Muraenidae
Moray eels are cosmopolitan eels of the family Muraenidae. The approximately 200 species in 15 genera are almost exclusively marine, but several species are regularly seen in brackish water and a few, for example the freshwater moray (Gymnothorax polyuranodon) can sometimes be found in freshwater. With a maximum length of 11.5 centimetres (4.5 in), the smallest moray is likely the Snyder's moray (Anarchias leucurus), while the longest species, the slender giant moray (Strophidon sathete) reaches up to 4 metres (13 ft). The largest in terms of total mass is the giant moray (Gymnothorax javanicus), which reaches almost 3 metres (9.8 ft) and can weigh over 36 kilograms (79 lb). [more]
Myrocongridae
The Myrocongridae or Thin eels are a small family of eels consisting of a single genus, Myroconger. Very little is known about the group. [more]
Nemichthyidae
Snipe eels are a family, Nemichthyidae, of eels that consists of nine species in three genera. They are pelagic fishes, found in every ocean, mostly at depths of 300-600 m but sometimes as deep as 4000 m. Depending on the species, adults may reach 1-2 m (30-60 inches) in length, yet they weigh only 80-400 g (a few ounces to a pound). They are distinguished by their very slender jaws that separate toward the tips as the upper jaw curves upward. The jaws appear similar to the beak of the bird called the snipe. Snipe eels are oviparous, and the juveniles, called Leptocephali (meaning small head), do not resemble the adults but have oval, leaf-shaped and transparent bodies. Different species of snipe eel have different shapes, sizes and colors. The similarly named bobtail snipe eel is actually in a different family and represented by two species, the black Cyema atrum and the bright red Neocyema erythrosoma. [more]
Nettastomatidae
The duckbill eels or witch eels are a family, Nettastomatidae, of eels. The name is from Greek netta meaning "duck" and stoma meaning "mouth". [more]
Ophichthidae
Ophichthidae is a family of eels, comprising species commonly called worm eels and snake eels. The term "Ophichthidae" comes from Greek ophis ("serpent") and ichthys ("fish"). [more]
Sawtooth eels are a family, Serrivomeridae, of eels found in temperate and tropical seas worldwide. [more]
Synaphobranchidae
Cutthroat eels are a family, Synaphobranchidae, of eels, the only member of the suborder Synaphobranchoidei. They are found worldwide in temperate and tropical seas. [more]
^ "The plight of the eel", BBC online, as seen at [3], accessed 22 January 2010, mentions that "Only 0.1ml/kg is enough to kill small mammals, such as a rabbit..."
^ "Blood serum of the eel." M. Sato. Nippon Biseibutsugakukai Zasshi (1917), 5 (No. 35), From: Abstracts Bact. 1, 474 (1917)
^ "Hemolytic and toxic properties of certain serums." Wm. J. Keffer, Albert E. Welsh. Mendel Bulletin (1936), 8 76-80.
^ Katz, J. (1998). "How to be a Dragon in Indo-European: Hittite illuyankas and its Linguistic and Cultural Congeners in Latin, Greek, and Germanic". In Jasanoff; Melchert; Oliver. M?r Curad. Studies in Honor of Calvert Watkins. Innsbruck. pp. 317?334. ISBN 3851246675.
