Difference between revisions of "Eel" - New World Encyclopedia
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| − | '''Eel''' is the common name for any of the various members of the [[fish]] order '''Anguilliformes''', which are characterized by an elongated, [[snake]]-like body, the absence of pelvic fins, and typically without [[scale (zoology)|scales]] or with the scales embedded in the skin. Eels are | + | '''Eel''' is the common name for any of the various members of the [[fish]] order '''Anguilliformes''', which are characterized by an elongated, [[snake]]-like body, the absence of pelvic fins, and typically without [[scale (zoology)|scales]] or with the scales embedded in the skin. Eels generally are found in marine environments or, as in the case of the freshwater eels (family Anguillidae), catadromous, spawning in marine environments and with the young eels traveling back into freshwater. |
| − | The common name eel is applied to | + | The common name eel also is applied to members of various species in the freshwater family Electrophoridae ([[electric eel]]s) of the order Gymnotiformes; the marine family Cyematidae (bobtail snipe eels) in the order Saccopharyngiformes; and in the largely freshwater order Synbranchifromes (including the swamp eels in family Synbranchidae and the spiny eels in family Mastacembelidae). However, the "true eels" are placed in order Anguilliformes which is also known as '''Apodes'''. |
| + | ==Description== | ||
| + | Eels, members of Anguilliformes, lack pelvic fins and the associated skeletal structures. The pectoral fins (in those species that have them) are at least midlateral in position or higher and lack the posttemporal bone, which connects the shoulder girdle to the skull. The caudal and anal fins are long, usually connecting with the tail (caudal) fin. The caudal fin lacks rays or may be absent. The body is very elongated. | ||
| − | + | The number of rays of the gill webbing ranges from 6 to 51, though sometimes they are absent altogether. The [[scale (zoology)|scales]] are usually absent, but if present are cycloid and embedded in the skin. | |
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| − | The | + | The flat and transparent [[larva]] of the eel is called a [[leptocephalus]]. A young eel is called an '''elver'''. Morphologically, the leptocephali larva of anguilliforms often differ considerably from the adults, to the extent that it is difficult to determine which leptocephali are the young of which adult (Nelson 1994). Most are less than 20 centimeters before they under [[metamorphosis]] to the adult, although some exceed 50 centimeters (Nelson 1994). |
| − | Depending on their species, eels can | + | Depending on their species, eels can range in length from 10 centimeters to 3 meters, and weigh up to 65 kilograms or more. The European conger, ''Conger conger'', is the largest of the eel family, reaching three meters in length, and perhaps weighing up to 110 kilograms. |
| − | + | Most eels prefer to dwell in shallow waters or hide at the bottom layer of the ocean, sometimes in holes. These holes are called eel pits. Only the [[Anguillidae]] family comes to fresh water to dwell (not to breed). Some eels dwell in deep water (in case of family [[Synaphobranchidae]], this comes to a depth of 4,000 m), or are active swimmers (the family [[Nemichthyidae]]—to the depth of 500 m). | |
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| − | Most eels prefer to dwell in shallow waters or hide at the bottom layer of the ocean, sometimes in holes. These holes are called eel pits. Only the [[Anguillidae]] family comes to fresh water to dwell | ||
The life cycle of the eel was a mystery for a very long time, because larval eels look very different from adult eels, and were thought to be a separate species. | The life cycle of the eel was a mystery for a very long time, because larval eels look very different from adult eels, and were thought to be a separate species. | ||
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[[Image:Moray eel kona.jpg|thumb|right|200px|A moray eel.]] [[image:rostrata.jpg|thumb|Juvenile [[American eel]]s]] | [[Image:Moray eel kona.jpg|thumb|right|200px|A moray eel.]] [[image:rostrata.jpg|thumb|Juvenile [[American eel]]s]] | ||
[[Image:FH000014.jpg|thumb|[[Garden eel]]s]] | [[Image:FH000014.jpg|thumb|[[Garden eel]]s]] | ||
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| − | + | Nelson (1994) recognizes 3 suborders, 15 families, 141 [[genus|genera]], and about 738 species in Anguilliformes. The following classification by [[FishBase]] recognizes 15 families but in 4 suborders. Among differences are the recognition by Nelson of suborders Anguilloidei (with 3 families), Muraenoidei (with 3 families), and Congroidei (with 9 families), while FishBase recognizes suborders Anguilloidei (with 6 families), Congroidei (with 6 families), Nemichthyoidei (with 2 families), and Synaphobranchoidei (with 1 family). In Nelson (1994), suborders Anguilloidei and Muraenoidei include the same families that FishBase includes in Anguilloidei. 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 FishBase system. | |
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==Suborders and families== | ==Suborders and families== | ||
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**Including Dysommidae, Nettodaridae, and Simenchelyidae | **Including Dysommidae, Nettodaridae, and Simenchelyidae | ||
| − | In some classifications the family [[Cyematidae]] of [[bobtail snipe eel]]s is included in the Anguilliformes, but in the FishBase system that family is included in the order [[Saccopharyngiformes]]. | + | In some classifications the family [[Cyematidae]] of [[bobtail snipe eel]]s is included in the Anguilliformes, but in the FishBase system and in Nelson (1994) that family is included in the order [[Saccopharyngiformes]]. The so-called "[[electric eel]]" of South America is not a true eel, but is more closely related to the [[carp]]. |
| − | + | ==Eels and humans== | |
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Freshwater eels (''[[unagi]]'') and marine eels ([[Conger eel]], ''[[anago fish|anago]]'') are commonly used in [[Japanese cuisine]]. [[Unadon]] is a very popular but rather expensive food. Eels are used in [[Cantonese cuisine|Cantonese]] and [[Shanghai cuisine]] too. The [[European eel]] and other freshwater eels are eaten in Europe, the United States, and other places around the world. A traditional [[East London, England|East London]] food is [[jellied eels]]. The [[Basque cuisine|Basque]] delicacy ''angulas'' consists of [[deep frying|deep-fried]] [[elvers|elver]].[http://www.buber.net/Basque/Food/food1.html]. [[New Zealand longfin eel]] is a traditional food for [[Maori]] in [[New Zealand]]. In [[Italian cuisine]] eels from the [[Comacchio]] area (a swampy zone along the [[Adriatic]] coast) are specially praised along with the freshwater ones of the [[Bolsena Lake]]. In northern [[Germany]], smoked eel is praised as a delicatesse. | Freshwater eels (''[[unagi]]'') and marine eels ([[Conger eel]], ''[[anago fish|anago]]'') are commonly used in [[Japanese cuisine]]. [[Unadon]] is a very popular but rather expensive food. Eels are used in [[Cantonese cuisine|Cantonese]] and [[Shanghai cuisine]] too. The [[European eel]] and other freshwater eels are eaten in Europe, the United States, and other places around the world. A traditional [[East London, England|East London]] food is [[jellied eels]]. The [[Basque cuisine|Basque]] delicacy ''angulas'' consists of [[deep frying|deep-fried]] [[elvers|elver]].[http://www.buber.net/Basque/Food/food1.html]. [[New Zealand longfin eel]] is a traditional food for [[Maori]] in [[New Zealand]]. In [[Italian cuisine]] eels from the [[Comacchio]] area (a swampy zone along the [[Adriatic]] coast) are specially praised along with the freshwater ones of the [[Bolsena Lake]]. In northern [[Germany]], smoked eel is praised as a delicatesse. | ||
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Eels are popular among marine aquarists in the [[United States]], particularly the [[Moray eel]] which is commonly kept in tropical saltwater aquariums. | Eels are popular among marine aquarists in the [[United States]], particularly the [[Moray eel]] which is commonly kept in tropical saltwater aquariums. | ||
| − | + | Fishing for eels is best done at night with either a gaff or a strong line with a small and square bloody piece of red meat. | |
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| + | Elvers were once eaten by fishermen as a cheap dish, but environmental changes have lead to increased rarity of the fish. They are now considered a delicacy and are priced at up to £700 per kg in the UK. | ||
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Eel blood is toxic. The toxic protein it contains is destroyed by cooking. The toxin derived from eel blood serum was used by [[Charles Robert Richet]] in his Nobel winning research which discovered [[anaphylaxis]] (by injecting it into dogs and observing the effect). | Eel blood is toxic. The toxic protein it contains is destroyed by cooking. The toxin derived from eel blood serum was used by [[Charles Robert Richet]] in his Nobel winning research which discovered [[anaphylaxis]] (by injecting it into dogs and observing the effect). | ||
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==References== | ==References== | ||
* {{FishBase order|order = Anguilliformes|month = January|year = 2006}} | * {{FishBase order|order = Anguilliformes|month = January|year = 2006}} | ||
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| + | Nelson | ||
[[Category:Life sciences]] | [[Category:Life sciences]] | ||
Revision as of 23:21, 29 September 2007
| True eels | ||||||||||
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 American eel, Anguilla rostrata
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See text for suborders and families. |
Eel is the common name for any of the various members of the fish order Anguilliformes, which are characterized by an elongated, snake-like body, the absence of pelvic fins, and typically without scales or with the scales embedded in the skin. Eels generally are found in marine environments or, as in the case of the freshwater eels (family Anguillidae), catadromous, spawning in marine environments and with the young eels traveling back into freshwater.
The common name eel also is applied to members of various species in the freshwater family Electrophoridae (electric eels) of the order Gymnotiformes; the marine family Cyematidae (bobtail snipe eels) in the order Saccopharyngiformes; and in the largely freshwater order Synbranchifromes (including the swamp eels in family Synbranchidae and the spiny eels in family Mastacembelidae). However, the "true eels" are placed in order Anguilliformes which is also known as Apodes.
Description
Eels, members of Anguilliformes, lack pelvic fins and the associated skeletal structures. The pectoral fins (in those species that have them) are at least midlateral in position or higher and lack the posttemporal bone, which connects the shoulder girdle to the skull. The caudal and anal fins are long, usually connecting with the tail (caudal) fin. The caudal fin lacks rays or may be absent. The body is very elongated.
The number of rays of the gill webbing ranges from 6 to 51, though sometimes they are absent altogether. The scales are usually absent, but if present are cycloid and embedded in the skin.
The flat and transparent larva of the eel is called a leptocephalus. A young eel is called an elver. Morphologically, the leptocephali larva of anguilliforms often differ considerably from the adults, to the extent that it is difficult to determine which leptocephali are the young of which adult (Nelson 1994). Most are less than 20 centimeters before they under metamorphosis to the adult, although some exceed 50 centimeters (Nelson 1994).
Depending on their species, eels can range in length from 10 centimeters to 3 meters, and weigh up to 65 kilograms or more. The European conger, Conger conger, is the largest of the eel family, reaching three meters in length, and perhaps weighing up to 110 kilograms.
Most eels prefer to dwell in shallow waters or hide at the bottom layer of the ocean, sometimes in holes. These holes are called eel pits. Only the Anguillidae family comes to fresh water to dwell (not to breed). Some eels dwell in deep water (in case of family Synaphobranchidae, this comes to a depth of 4,000 m), or are active swimmers (the family Nemichthyidae—to the depth of 500 m).
The life cycle of the eel was a mystery for a very long time, because larval eels look very different from adult eels, and were thought to be a separate species.
Classification
Nelson (1994) recognizes 3 suborders, 15 families, 141 genera, and about 738 species in Anguilliformes. The following classification by FishBase recognizes 15 families but in 4 suborders. Among differences are the recognition by Nelson of suborders Anguilloidei (with 3 families), Muraenoidei (with 3 families), and Congroidei (with 9 families), while FishBase recognizes suborders Anguilloidei (with 6 families), Congroidei (with 6 families), Nemichthyoidei (with 2 families), and Synaphobranchoidei (with 1 family). In Nelson (1994), suborders Anguilloidei and Muraenoidei include the same families that FishBase includes in Anguilloidei. 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 FishBase system.
Suborders and families
Suborder Anguilloidei
- Anguillidae (freshwater eels)
- Chlopsidae (false morays)
- Heterenchelyidae
- Moringuidae (spaghetti eels)
- Muraenidae (moray eels)
- Myrocongridae
Suborder Congroidei
- Colocongridae
- Congridae (congers)
- Including Macrocephenchelyidae
- Derichthyidae (longneck eels)
- Including Nessorhamphidae
- Muraenesocidae (conger pikes)
- Nettastomatidae (witch eels)
- Ophichthidae (snake eels)
Suborder Nemichthyoidei
- Nemichthyidae (snipe eels)
- Serrivomeridae (sawtooth eels)
Suborder Synaphobranchoidei
- Synaphobranchidae (cutthroat eels)
- 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 and in Nelson (1994) that family is included in the order Saccopharyngiformes. The so-called "electric eel" of South America is not a true eel, but is more closely related to the carp.
Eels and humans
Freshwater eels (unagi) and marine eels (Conger eel, anago) are commonly used in Japanese cuisine. Unadon is a very popular but rather expensive food. Eels are used in Cantonese and Shanghai cuisine too. The European eel and other freshwater eels are eaten in Europe, the United States, and other places around the world. A traditional East London food is jellied eels. The Basque delicacy angulas consists of deep-fried elver.[1]. New Zealand longfin eel is a traditional food for Maori in New Zealand. In Italian cuisine eels from the Comacchio area (a swampy zone along the Adriatic coast) are specially praised along with the freshwater ones of the Bolsena Lake. In northern Germany, smoked eel is praised as a delicatesse.
Eels are popular among marine aquarists in the United States, particularly the Moray eel which is commonly kept in tropical saltwater aquariums.
Fishing for eels is best done at night with either a gaff or a strong line with a small and square bloody piece of red meat.
Elvers were once eaten by fishermen as a cheap dish, but environmental changes have lead to increased rarity of the fish. They are now considered a delicacy and are priced at up to £700 per kg in the UK.
Eel blood is toxic. The toxic protein it contains is destroyed by cooking. The toxin derived from eel blood serum was used by Charles Robert Richet in his Nobel winning research which discovered anaphylaxis (by injecting it into dogs and observing the effect).
ReferencesISBN links support NWE through referral fees
- "Anguilliformes". FishBase. Ed. Ranier Froese and Daniel Pauly. January 2006 version. N.p.: FishBase, 2006.
Nelson
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