Eel

True eels are of the order Anguilliformes, which consists of 4 suborders, 19 families, 110 genera and 400 species. Most eels are predators.

The flat and transparent larva of the eel is called a leptocephalus. A young eel is called an elver.

Most eels prefer to dwell in shallow waters or hide at the bottom layer of the ocean, sometimes in holes. Only the Anguillidae family comes to fresh water to dwell there (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).

Biology

Description

Eels lack pelvic fins and the associated skeletal structures, the pectoral fins (when present) are midlateral in position and lack the bone connecting the shoulder girdle to the skull (the posttemporal). 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 obviously is very elongated (or Eel like).

The number of rays of the gill webbing ranges from 6 to 51, though sometimes they are absent altogether. The scales are cycloid or absent.

Depending on their species, eels can reach from 10 cm to 3 m, and weigh up to 65 kg.

Life cycle

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.

Use by humans

Freshwater eels (unagi) and marine eels (Conger eel, anago) are commonly used in Japanese cuisine. 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 London food is jellied eels. The Basque delicacy, angulas, consists of deep-fried elvers.^*

Classification

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 FishBase system.

Suborder Anguilloidei

Suborder Nemichthyoidei

Nemichthyidae (snipe eels)
Serrivomeridae (sawtooth eels)

Suborder Congroidei

Colocongridae
Congridae (congers)
- Including Macrocephenchelyidae
Muraenesocidae (conger pikes)
Nettastomatidae (witch eels)
Derichthyidae (longneck eels)
- Including Nessorhamphidae
Ophichthidae (snake eels)

Suborder Synaphobranchoidei

Synaphobranchidae (cutthroat eels)
- Including Simenchelyidae, Nettodaridae, and Dysommidae

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.

Trivia

In recent years, some cryptozoologists have theorised that the Loch Ness Monster might be a giant eel (as was the case in Steve Alten's novel The Loch, where the monster was a giant Sargasso anguilla eel).

There is an urban legend that wallets made out of electric eels will demagnetize your credit cards. This was proven to be untrue in an episode of the Mythbusters TV show. Actually, as pointed out in the Straight Dope, eel-skin wallets are made from hagfish which are unrelated to electric eels.^* Furthermore, it seems that magnetic clasps, not eel leather, are to blame for demagnetization.

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).

Food

Eel is treated as nourishment in Asia. Especially in Japan, Unadon is a very popular (but a bit expensive) food.

References

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