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EEL

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Originally appearing in Volume V09, Page 9 of the 1911 Encyclopedia Britannica.
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EEL  . The See also:

common See also:freshwater eel (See also:Lat. See also:anguilla; O . Eng. cel) belongs to a See also:group of soft-rayed fishes distinguished by the presence of an opening to the See also:air-See also:bladder and the See also:absence of the pelvic fins . With its nearest relatives it forms the See also:family Muraenidae, all of which are of elongated cylindrical See also:form . The peculiarities of the eel are the rudimentary scales buried in the skin, the well-See also:developed See also:pectoral fins, the rounded tail fin continuous with the dorsal and ventral fins . Only one other See also:species of the family occurs in See also:British See also:waters, namely, the conger, which is usually much larger and lives in the See also:sea . In the conger the eyes are larger than in the eel, and the upper See also:jaw overlaps the See also:lower, whereas in the eel the lower jaw projects beyond the upper . Both species are voracious and predatory, and feed on almost any See also:animal See also:food they can obtain, living or dead . The conger is especially fond of squid or other Cephalopods, while the eel greedily devours carrion . The common eel occurs in all the See also:rivers and fresh waters of See also:Europe, except those draining towards the See also:Arctic Ocean, the See also:Black Sea and the See also:Caspian Sea . It also occurs on the See also:Atlantic See also:side of See also:North See also:America . The conger has a wider range, extending from the western and See also:southern shores of See also:Britain and See also:Ireland to the See also:East See also:Indian See also:Archipelago and See also:Japan .

It is common in the Mediterranean . The ovaries of the eel resemble somewhat those of the See also:

salmon in structure, not forming closed sacs, as in the See also:majority of Teleostei, but consisting of laminae exposed to the See also:body cavity . The laminae in which the eggs are produced are very numerous, and are attached transversely by their inner edges to a membranous See also:band See also:running nearly the whole length of the body-cavity . The majority of the eels captured for See also:market are See also:females with the ovaries in an immature See also:condition . The male eel was first discovered in 1873 by Syrski at See also:Trieste, the testis being described by him as a lobed elongated See also:organ, in the same relative position as the ovary in the See also:female, surrounded by a smooth See also:surface without laminae . He did not find ripe spermatozoa . He discovered the male by examining small specimens, all the larger being female . L . Jacoby, a later observer, found no See also:males exceeding 19 in. in length, while the female may reach a length of 39 in. or more . Dr C . G . J .

Petersen, in a See also:

paper published in 1896, states that in See also:Denmark two kinds of eels are distinguished by the fishermen, namely, yellow eels and See also:silver eels . The silver eels are further distinguished by the shape of the snout and the See also:size of the eyes . The snout in front of the eyes is not See also:flat, as in the yellow eels, but high and compressed, and therefore appears more pointed, while the eyes are much larger and directed outwards . In both kinds there are males and females, but Petersen shows that the yellow eels See also:change into silver eels when they migrate to the sea . The sexual See also:organs in the silver eels are more developed than in the yellow eels, and the former have almost or entirely ceased to take food . The male silver eels are from 111 to 19 in. in length, the females from 161 to about 39 in . It is evident, therefore, that if eels only spawn once, they do not all reach the same size when they become sexually mature . The male conger was first described in 1879 by See also:Hermes, who obtained a ripe specimen in the See also:Berlin See also:Aquarium . This specimen was not quite 21 ft. in length, and of the numerous males which have been identified at the See also:Plymouth Laboratory, none exceeded this length . The large See also:numbers of conger above this size caught for the market are all immature females . Female conger of 5 or 6 ft. in length and weighing from 30 to 50 lb are common enough, and occasion-ally they exceed these limits . The largest recorded was 8 ft .

3 in. See also:

long, and weighed 128 lb . There is every See also:reason to believe that eels and conger spawn but once in their lives, and See also:die soon after they have discharged their generative products . When kept in aquaria, both male and female conger are vigorous and voracious . The males sooner or later cease to feed, and attain to the sexually mature condition, emitting ripe milt when handled and gently squeezed . They live in this condition five or six months, taking no food and showing See also:gradual wasting and disease of the bodily organs . The eyes and skin become ulcerated, the sight is entirely lost, and the bones become soft through loss of See also:lime . The females also after a See also:time cease to feed, and live in a See also:fasting condition for five or six months, during which time the ovaries develop and reach See also:great size and See also:weight, while the bones become soft and the See also:teeth disappear . The female, however, always See also:dies in confinement before the ova are perfectly ripe and before they are liberated from the ovarian See also:tissue . The absence of some necessary condition, perhaps merely of the pressure which exists at the bottom of the sea, evidently prevents the See also:complete development of the ovary . The invariable See also:death of the See also:fish in the same almost ripe condition leads to the conclusion that under normal conditions the fish dies after the mature ova have been discharged . G . B .

Phoenix-squares

Grassi states that he obtained ripe male eels, and ripe specimens of See also:

Muraena, another genus of the family, hi the whirlpools of the Strait of See also:Messina . A ripe female Muraena has also been described at See also:Zanzibar . Gravid female eels, i.e. specimens with ovaries greatly enlarged, have been occasionally obtained in fresh See also:water, but there is no doubt that, normally, sexual maturity is attained only in the sea . Until See also:recent years nothing was known from See also:direct observation concerning the See also:reproduction of the common eel or any species of the family . It was a well-known fact that large eels migrated towards the sea in autumn, and that in the See also:spring small trans-See also:parent eels of 2 in. in length and upwards were common on the See also:shore under stones, and ascended rivers and streams in vast swarms . It was reasonable, therefore, to infer that the mature eels spawned in the sea, and that there the See also:young were developed . A group of See also:peculiar small fishes were, however, known which were called Leptocephali, from the small proportional size of the See also:head . The first of these described was captured in 17b3 near See also:Holyhead, and became the type of L . Morrisii, other specimens of which have been taken either near the shore or at the surface of the sea . Other forms placed in the same genus had been taken by surface fishing in the Mediterranean and in tropical ocean currents . The See also:chief peculiarities of Leptocephali, in addition to the smallness of the head, are their ribbon-like shape and their glassy transparency during See also:life . The body is flattened from side to side, and broad from the dorsal to the ventral edge .

Like the eels, they are destitute of pelvic fins. and no generative organs have been observed in them (see fig.) . In 1864 the See also:

American naturalist, T . N . Gill, published the conclusion that L . Morrisii was the young or larva of the conger, and Leptocephali generally the young stages of species of Muraenidae . In 1886 this conclusion was confirmed from direct observation by Yves Delage, who kept alive in a tank at See also:Roscoff a specimen of L . Morrisii, and saw it gradually transformed into a young conger . From 1887 to 1892 See also:Professor Grassi and Dr Calandruccio carried on careful and successful researches into the development of the Leptocephali at See also:Catania, in See also:Sicily . The specimens were captured in considerable numbers in the See also:harbour, and the transformation of L . Morrisii into young conger, and of various other forms of Leptocephalus into other genera of Muraenidae, such as Muraena, Congromuraena and Ophichthys, was observed . In 1894 the same authors published the announcement that another species of Leptocephalus, namely, L. brevirostris, was the larva of the common eel . This larval form was captured in numbers with other Leptocephali in the strong currents of the Strait of Messina .

In the See also:

metamorphosis of all Leptocephali a great reduction in size occurs . The L. brevirostris reaches a length of 8 cm., or a little more than 22 in., while the perfectly-formed young eel is 2 in. long or a little more . The See also:Italian naturalists have also satisfied themselves that certain pelagic fish eggs originally described by Raffaele at See also:Naples are the eggs of Muraenidae, and that among them are the eggs of Conger and Anguilla . They believe that these eggs, although See also:free in the water, remain usually near the bottom at great depths, and that fertilization takes See also:place under similar conditions . No fish eggs of the See also:kind to which reference is here made have yet been obtained on the British coasts, although conger and eels are so abundant there . Raffaele described and figured the larva newly hatched from one of the eggs under See also:consideration, and it is evident that this larva is the earliest See also:stage of a Leptocephalus . Although young eels, some of them more or less flat and transparent, are common enough on the coasts of Great Britain and north-western Europe in spring, neither eggs nor specimens of Leptocephalus brevirostris have yet been taken in the North Sea, See also:English Channel or other shallow waters in the See also:neighbour-See also:hood of the British Islands, or in the Baltic . Marked eels have been proved to migrate from the inmost See also:part of the Baltic to the Kattegat . Recently, however, See also:search has been made for the larvae in the more distant and deeper portions of the Atlantic Ocean . In May 1904 a true larval specimen was taken at the surface See also:south-See also:west of the See also:Faeroe Islands, arid another was taken 40 M. north by west of See also:Achill Head, Ireland . In 1905 numbers were taken in deep water in the Atlantic . The See also:evidence at See also:present available indicates that the spawning of mature eels takes place beyond the 10o See also:fathom See also:line, and that the young eels which reach the See also:coast are already a See also:year old .

As eels, both young and old, are able to live for a long time out of water and have the See also:

habit of travelling at See also:night over See also:land in wet grass and in See also:damp See also:weather, there is no difficulty in explaining their presence in See also:wells, ponds or other isolated bodies of fresh water at any distance from the sea . See " The Eel Question," See also:Report U.S . See also:Commissioner of See also:Fisheries for 2879 (See also:Washington, 1882); J . T . See also:Cunningham, " Reproduction and Development of the Conger," Journ . See also:Mar . Biol . Assn. vol. ii.; C . G . J . Petersen, Report See also:Dan . Biol .

Station, v . (1894) ; G . B . Grassi, Quart . Journ . Mic . Sci. vol. xxxix . (1897) . (J . T .

End of Article: EEL
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Additional information and Comments

I used to live on a farm in Cornwall where an eel lived in the well in the meadow. I didn't have much knowledge of 'country matters' but the local farming community told me it was traditional for eels to be encouraged to live in wells as they acted as a natural water filter, preventing us humans from being poisoned. Is this true?
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