1902 Encyclopedia > Eel

Eel




EEL. a name applied more or less generally to all the species of Murcenidce, a family of soft-finned apodal fishes, but more specially applicable to the species belonging to the sub-family Angnillina. The body throughout the family of eels is greatly elongated and of snake-like form. The ventral fins are awanting in all the species, while in certain forms, as the Mursena, the pectoral fins are also absent. The skin is thick and soft, and is covered over with a glutinous secretion which gives the eel its proverbial slipperiness. It is also sufficiently tough to enable it to be stripped entire from the body, and in some countries the skin is thus used as a bag or purse. Scales, disposed in groups, are present in the eels belonging to the genus Anguilla, but they are so buried beneath the outer layer or scarf skin as not to be apparent, while in such forms as the conger they are altogether awanting. The bronchial openings are small, and lead into a sac, from which another sac is given off. The gills are thus exposed but slightly to the drying influence of the atmosphere, and it is owing to this, and to the slimy condition of the skin, that eels can exist for a considerable time out of water. According to Dr Giinther, the Murcenidce comprise 26 genera and 230 species, inhabiting the seas and fresh waters of temperate and tropical regions. Of these only the true eels, Anguilla, inhabit fresh water, although most of the latter are likewise marine.

Although abounding in almost every river, lake, and estuary in Europe, little was known until recently of the life-history of the fresh-water eels. With regard to their origin Aristotle believed that they sprang from the mud, Pliny that they took their rise from portions of the skin scraped off the parent body, while horse hairs and May-dew have both been regarded as fertile sources of eels. Until quite recently, they were regarded by naturalists as viviparous, a mistake which probably arose from the fre-quent presence of parasitic worms, supposed to be the young, in their bodies, and the absence of anything exactly resembling milt and roe as usually found. Like ali other Teleostean fishes they are oviparous, the milt and roe occur-ring in the same position, but differing considerably in appearance from those elements in other fishes. The spawn of the eel is generally deposited in sand and mud at the mouths of rivers, and in harbours where the water is brackish. To reach these spawning grounds, eels migrate in |. autumn down the river channels, and at those times they are taken in large numbers by various devices, such as the " eel-buck" of the Thames, a wooden framework supporting wicker baskets, the mouths of which are opposed to the stream, and which are so constructed that the fish when once inside is unable to extricate itself. When there are obstacles in the way of their getting to the sea, eels are known to deposit their spawn in the beds of fresh-water streams, but it is still doubtful whether this may not also occur in cases where the sea is quite accessible. Eels are peculiarly averse \to cold, and the fact that the temperature of the brackish waters of estuaries is always higher than that of unmixed salt or fresh water is an additional reason for their seaward migration on the approach of winter. In performing this journey the darkest nights are chosen, the moonlight being sufficient to stay their progress. During the cold of winter they lose their appetite and become torpid, large numbers of them congregating together for the sake of the additional warmth thus obtained, and burying themselves to a depth of 12 to 16 inches in places where the receding tide leaves them dry. In such places they are taken in large numbers by means of eel-spears. In Somersetshire, according to Yarrell, " the people know how to find the holes in the banks of the rivers in which eels are laid up, by the hoar frost not lying over them as it does elsewhere, and dig them out in heaps." In spring, the migration of the young eels up the rivers takes place, the parents, according to some observers, performing a similar journey. This migration takes place from February to May, according to the temperature, and some idea of the vast numbers of young eels which annually pass up our rivers may be formed from the fact that 1800 of them, each about 3 inches long, have been observed to pass a given point on the Thames in a single minute. This monster procession of elvers, as these young eels are called, is known on the Thames as eel-fare, and usually takes place about the beginning of May; and at these times, unfortunately, they are often caught in countless numbers in sieves, especially on the Severn, cartloads of them being sometimes seen for sale in the Exeter market. This upward migration, unlike that of autumn, is performed entirely by day, and it is carried through in spite of obstacles apparently insuperable to a fish. Eels have been known to climb up steep ascents, 20 feet above the water, showing great skill and ingenuity in availing themselves of whatever natural aids the locality might afford. Couch tells of a remark-able case in the neighbourhood of Bristol, where the elvers passed from one stream to another by means of a tree which stood between, and the branches of which dipped into the water of the lower. Ascending by these, the eels dropped from the branches on the opposite side into the upper stream. In some parts of Ireland the fishermen place haybands on the rocky parts of the river-courses, iu order to facilitate the upward progress of the eels. The most effectual obstacle, however, to their advance in either direction is found in a muddy or polluted state of the water ; and old eels, to get rid of such nauseous conditions, have been known to leave the water and travel for considerable distances in search of purer surroundings. When confined also in ponds they often show their migratory instinct by leaving these in the night time, and attempting to make their way to the nearest river or to the sea.





Like most animals that pass the winter in a torpid condition, eels are exceedingly voracious during the summer months, occasionally eating vegetables, but generally preferring such animal food as young fishes, worms, and the larvae of insects; they have also been known to devour much larger creatures, as water-hens, rats, and snakes. Although their food is thus very various, it is essential that it be fresh, eels at once rejecting whatever their keen sense of smell detects as tainted. Eels were held in great esteem by the Greeks and Romans, and enormous prices were sometimes paid for them ; by the Egyptians, on the other hand, they were held in abhorrence. Their snake-like appearance has had much to do with the prejudice entertained by many people against eels, and to this may be attributed the fact that in Scotland this valuable fish is almost wholly rejected as an article of food. Their value in this respect has, however, been recognized in England from very early times, the taste for eels having probably been acquired during the Roman occupation. The Vener-able Bede states that England in his time was famous for its salmon and eel fisheries, and Ely is said to have got its name from the abundance of the eels in that fenny neighbourhood. Eels are very largely consumed in London, the greater proportion of these, numbering about 10 millions, being brought alive annually from Holland in welled boats. The greatest eel-breeding establishment in the world is that at Comacchio on the Adriatic, where an immense swamp, bounded and fed by two of the mouths of the river Po, 140 miles in circumference, has been utilized for this purpose. The industry is very ancient, having yielded in the 16th century an annual revenue to the Roman Pontiffs, in whose territory it was, of £12,000. The eels are cooked at Comacchio, and forwarded to the principal towns of Italy.

The best known and most widely distributed fresh-water species is the Sharp-nosed Eel (Anguilla vulgaris). It occurs, according to Dr Giinther, in Europe to 64" 30' N. lat., in the Mediterranean region, and in North America, but neither in the Danube, nor in the Black and Caspian Seas. Like all other eels it is of comparatively slow growth, but often attains a large size, measuring sometimes 5 feet in length, and weighing in such cases from 20 to 30 lb. Few eels, however, weigh more than 6 lb. They are believed to be long-lived, one authentic instance being known of an eel which was at least 31 years old. The colour of the species is generally dark olive-green on the upper surface, becoming lighter on the sides, and white beneath; but the colour depends somewhat on the nature of the stream it inhabits, those obtained in pure water being known as silver eels from the lightness of their colour, while those found in muddy rivers are darker.

The Conger {Conger vulgaris) is the only British species of sea-eel. It differs from the true eels in having the upper jaw projecting beyond the lower, and in the entire absence of scales. It is abundant in all parts of the British coasts, especially on rocky ground, and attains a length of 10 feet, weighing in large examples over 100 ft. The conger is exceedingly voracious, feeding on other fishes, and not sparing even its own kind. Its jaws are strong and well-armed, and the capture of a large specimen is not unattended with danger to the fisherman. Its tail is exceedingly sensitive and prehensile, the conger being able with this organ to grasp the gunwale of the boat, and by a sudden contraction of the muscles to throw itself overboard, a smart blow on the tail, however, is sufficient to prevent the possibility of this occurrence. The conger is peculiarly sensitive to cold, and during severe frosts it is often taken floating helplessly on the surface of the sea. Mr F. Buckland states that in 1855 thousands of congers were found floating upon the water ; they could progress readily in any direction on the surface, but could not descend, and consequently fell an easy prey to the boat-men. In this way, no less than 80 tons were captured. " The action of the frost," he says, " caused the air in their swimming bladders to expand so much that the ordinary muscles could not expel it at will." The chief conger fisheries are on the south and west coasts of England, but these are not nsarly so productive now as they formerly were. The flesh is not held in much esteem.

The Electric Eel (Gymnotus eledricus) belongs to a different family of apodal fishes (Gymnotichx). In it both caudal and dorsal fins are entirely awanting, and the anal fin is very long, forming a fringe from the throat to the extremity of the tail. It attains a length of 5 or 6 feet, and frequents the marshes of Brazil and the Guianas, where it is regarded with terror, owing to the formidable electrical apparatus with which it is provided, and which extends along each side of the lower portion of the tail. When this; natural battery is discharged in a favourable position, if is sufficiently powerful to kill the largest animal; and, according to Humboldt, it has been found necessary to change the line of certain roads, owing to the number of horses that were annually killed in passing through the pools frequented by the gymnoti. These eels are eaten by the Indians, who, before attempting to capture them, seek to exhaust their electrical power by driving horses into the ponds. By repeated discharges upon these, they gradually expend this marvellous force; after which, being defence-less, they become timid, and approach the edge for shelter, when they fall an easy prey to the harpoon of the Indian. It is only after long rest and abundance of food, that this fish is able to resume the use of its subtle weapon. (j. GI.)







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