Eel, a name applied to several malacopterous fishes of the families anguillidoe, congeridoe, and muroenidoe, especially to the typical genera anguilla (Cuv.), conger (Cuv.), and muroena (Thunb.). From their snake-like appearance, and the absence of ventral fins or posterior limbs, they have been called anguiform apodes; they all have the body more or less elongated and cylindrical, no ribs in the skeleton, a caecal stomach, and simple not-jointed fin rays. In the genus anguilla, to which the common eel belongs, the scarcely apparent scales are cycloid, narrow, oblong, arranged in groups at right angles to each other, forming a kind of lattice-work under the cuticle; the whole skin is soft and slimy, thickly studded with muciparous glands and ducts; the nostrils are double, each having two orifices, the anterior prolonged into a tube, and the posterior opening above the mouth; the teeth are card-like or villiform in both jaws, and a few on the anterior part of the vomer; the gill opening on each side is very small, and just in front of the pectoral fin, which exists in all the species; the dorsal fin begins at a considerable distance from the head, behind the pectorals, and forms a continuous fin with the caudal and anal; the lower jaw is longer than the upper.
About 50 species are described. The common eel of the northern and middle states (A. Bostoniensis, Lesueur, and vulgaris, Mitch.) is greenish or olive-brown above, and yellowish or yellowish white beneath, often with a reddish tinge along the anal fin; in a specimen 2 ft. long, measured by Dr. Storer, the short pectorals were about 8 in. from the end of the snout. The eel inhabits both salt and fresh water, from the British provinces to the southern states, wherever it can find its favorite muddy bottoms and extensive flats; it prefers shallows near the shore, where it may be caught in great numbers by hook and line, by bobbing, and by spearing; the places frequented by it are called eel grounds, in which during winter the fishes bed themselves in the soft mud to the depth of about a foot, and are then speared through holes cut in the ice; the best time for catching them is at night, by torchlight. During their passage up and down rivers they are taken in baskets and pots baited with fish or any decaying matter. The eel is very voracious and quite omnivorous; when in good condition it is well flavored, though from its snake-like appearance (and it is only in form that it resembles a snake) most persons are prejudiced against it.
The length varies from 6 in. to 2 1/2 ft.; in summer it is sometimes seen weighing several pounds. At the mouths of the rivers emptying into Boston harbor eels are caught in nets, 15 or 20 bushels at a time, and are kept alive until wanted in ditches supplied by the tide. The silver eel (A. argentea, Les.) is silvery gray, darker above, and satiny white below; the pectorals are nearer the head than in the common species, of which, however, it is considered by some only a variety; it is taken in pots in October, when it leaves the ponds. A large species, caught in the lakes of western New York, is the beaked eel (A. rostrata, Les.); the snout is elongated and pointed; the upper parts are olive-gray, sometimes slaty blue, and the lower parts white; the dorsal and anal fins reddish; length about 2 ft. The common eel of Europe (A. acutirostris, Yarrell) has a sharper snout than ours; it is highly esteemed as food, and the London market is supplied principally from Holland, from which the eels are brought alive in vessels carrying each from 15,000 to 20,000 lbs. Eels are much esteemed in other countries, especially, according to Ellis, in Polynesia, where they are often tamed and fed until they attain an enormous size.
They are prolific, hardy, and easily preserved in salt, fresh, or brackish water. They make two migrations annually, one in autumn to the sea, the other in spring or summer from the sea to the rivers. They are not found in arctic regions, nor in the rivers of the extreme north of Europe; even in temperate regions, at the approach of winter, they bury themselves in the mud, remaining torpid until spring; they remain without food, breathing hardly at all, at a low animal temperature, and almost motionless; yet the irritability of the muscular fibre is very great, as is shown by the restless motions of eels during thunderstorms, and by their well known movements after the skin has been removed. Though not possessing the respiratory pouches of the anabas, the eel is able to survive a long time out of water, simply because the gills remain moist from the small size of the branchial orifices; by this means it traverses considerable distances on land, moving like a snake through the grass; this explains the appearance of eels in fish ponds from which the utmost care has been taken to exclude them, on account of their destruction of the spawn and young of more valuable fishes; they have been often seen performing such overland journeys at night.
Eels are found in fresh water which has no communication with the sea; having a capacious air bladder, they are able to ascend rapidly to the surface, and sometimes swim very high in deep water; though slow of growth, they attain a large size under favorable circumstances, having been caught in England weighing 27 lbs. The town of Ely is said to have been so named from the rents having been formerly paid in eels, the lords of the manor being annually entitled to more than 100,000; Elmore, on the Severn, was so called from the immense number of these fish there taken; so also Aalborg (Eel Town) in Denmark, etc. - The conger eels differ from the genus anguilla in having the dorsal fin begin nearer the head, at or even in front of the pectoral, and in having the upper jaw the longer; the anterior nostrils open by short tubes close to the end of the snout, and the posterior in front of the large eyes; the teeth of the palate and vomer are slender, with chisel-shaped crowns, and closely arranged; the skin is naked and scaleless, and the tail elongated and pointed; in other respects they resemble the common eel.
The American conger (conger occidentalis, De Kay) is olive-brown above and whitish below; the dorsal and anal fins are transparent, with a dark border; the lateral line is distinct, with a series of white dots; it is from 3 to 5 ft. long, and either this or another species is found from the gulf of St. Lawrence southward as far as the coast of New Jersey. The European conger (C. vulgaris, Cuv.) is common on the coast of Cornwall, on the eastern rocky shores, and in banks off the coast of France; it is caught on lines, the best bait being the sand launce (ammodytes) or the pilchard, and the fishing is performed at night; great numbers are taken, and meet with a ready sale at a low price to the poorer classes, But it is not held in much estimation. Congers are very voracious, and specimens have been caught weighing 130 lbs., more than 10 ft. long and 18 in. in circumference; they are very strong, bite sharply, and have great tenacity of life. As many as 156 vertebrae have been found in the conger, about 40 more than are found in the eel; they spawn in December and January. Sir John Richardson alludes to nine species. - The eel of the Mediterranean, so famous in the days of ancient Rome, belongs to the genus muroena, characterized by the absence of pectorals, smooth and scaleless skin, small lateral branchial orifice on each side, and the united dorsal and anal fins, low and fleshy, hardly distinguishable beyond the margin of the body; the teeth are arranged in a single row around the edge of the nasal bone, with a few on the longitudinal median line.
More than 20 species are described, attaining the size of 4 or 5 ft.; one (M. moringa, Cuv.) was found by Catesby at the Bahama islands. The classic species of the Mediterranean (M. Helena, Linn.), the Roman muroena, grows to the length of 4 or 5 ft.; the color is a purplish brown, marked with sub-angular yellow markings, and spotted with beautiful shades of yellow, purple, golden yellow, and white; the anterior nostrils open near the end of the snout, the posterior just above the eyes; the cheeks are rather tumid from muscular development. It has been caught on the English coast, but it abounds in the Mediterranean; great numbers were consumed by the ancient Romans, who kept them in ponds, and placed them alive on the table in crystal vessels, that the guests might admire their beautiful colors before they were cooked. Caesar is said to have distributed 6,000 of these fishes among his friends on the celebration of one of his triumphs. They are very voracious, fierce, and tenacious of life, and are said sometimes to have been fed on the flesh of slaves who had offended their Roman masters. Their bite is much dreaded by the fishermen. The flesh is white, delicate, and much esteemed.
There are many species, exclusively marine. - The sand eel (ammodytes Americanus, De Kay) has an elongated, slightly compressed body, large gill openings, a dorsal fin extending nearly the whole length of the back, and an anal fin of considerable size, both separated from the caudal; the lower jaw the longer; the color is yellowish or bluish brown above, mixed with silvery and light green; the sides and abdomen are silvery; the length is from 6 to 12 in. This species is found from the coast of Labrador to that of New York; in the provinces it is largely used as bait for cod; it is very common in Long Island sound from May to November, constituting in its season the principal food of the bluefish and bass; it is also eaten by eels and other fish; the cephalopod cuttle fish preys upon it extensively; like the tropical flying fish, it is pursued by fishes in the water, and by gulls and terns in the air. The names of sand launce and ammodytes are given it from its habit of darting out of and into the sand head foremost and instantly, by means of its projecting lower jaw. Its food is principally insects. On the coast of England it is esteemed as food, and is raked out of the sand at low tide in great numbers; it is also caught in seines.
Two species are described.
Common Eel (Anguilla vulgaris).
Conger Eel (Conger occidentalis).