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What is an Eel?

Mary McMahon
Mary McMahon
Mary McMahon
Mary McMahon

Eels are snakelike fish with elongated bodies and shallow fins. They can be found in both fresh and saltwater, depending upon the species, although all breed in salt water. Many species of freshwater eel are consumed by humans, and the fish is popular in European and Asian cuisines. Some species harvested by humans are under threat, and several nations have undertaken measures to ensure the health of their stocks.

The eel is a very peculiar fish, with an imperfectly understood life cycle. All spawn at sea, many of them in the Sargasso Sea. The larva drift with the currents as they mature into young, called glass eels, a totally transparent form. Glass eels are often found coastal areas and, in the autumn, they move into estuaries, where they turn into pigmented young known as elvers. Elvers migrate upriver, often over very long distances, and many species spend their entire lives in fresh water. In this stage, the fish are known as yellow eels and will reach a mature length which can range between 2 and 5 feet (0.5 and 1.5 meters) in length, depending upon the species.

Many eels spawn in the Sargasso Sea, which is named for its copious amounts of Sargassum seaweed.
Many eels spawn in the Sargasso Sea, which is named for its copious amounts of Sargassum seaweed.

When the fish reach sexual maturity, they undergo additional physical changes, turning gray with a pale belly. The pectoral fins and eyes of the eel enlarge, presumably to assist the fish in its migration back to the spawning area at sea, where it will die after mating. Since scientists have not actually witnessed the spawning process, biological information about the early life of eels is primarily conjecture.

Some eels, such as the moray, spend their entire lives at sea, lurking in crevasses and deeper ocean water. The moray is a well known family, because members tend to be vicious and are equipped with extremely sharp teeth that have been known to chip bone. Swimmers are encouraged to avoid morays, although they can be perfectly harmless and even friendly if they do not feel threatened. Many fish have the common name of eel, such as electric eels, although they are not in fact part of the Anguilliformes order.

Freshwater eels are commercially fished by several nations, and the global stocks of the fish are in decline. This may partially be due to the fact that the fish can take up to 20 years to mature, and some countries may have fished out their stocks of potentially viable mature eels. Because the life of the eel is not fully understood, the damage caused by commercial fishing may be more severe than was originally thought. Several nations are working together to conserve and rebuild their stocks, since the eel provides vital economic and cultural benefits to many countries.

Frequently Asked Questions

What exactly is an eel?

An eel is a long, slender fish that can be found in both fresh and saltwater environments. They belong to the order Anguilliformes, which includes over 800 species. Eels are known for their snake-like bodies and lack of pelvic fins. Many species are also capable of producing electric charges, used for navigation and defense.

How do eels reproduce?

Eels have a fascinating life cycle. For instance, the European eel migrates over 3,700 miles to the Sargasso Sea to spawn, according to the National Oceanic and Atmospheric Administration. They lay their eggs in the sea, and the larvae then drift towards the coast, where they grow into glass eels before heading upstream into freshwater to mature.

Are all eels electric?

No, not all eels are electric. The term "electric eel" is actually a misnomer as they are not true eels but rather belong to the knifefish family. True eels, such as those in the Anguilliformes order, do not generate electricity. Only a few species like the electric eel have this ability, which they use for hunting and self-defense.

What do eels eat?

Eels are generally carnivorous and have a varied diet depending on their species and habitat. They can eat invertebrates, fish, and even small mammals or birds. Some eels are known to be opportunistic feeders, consuming dead or decaying matter, while others are active predators, using their sharp teeth to capture prey.

How long can eels live?

The lifespan of an eel varies significantly among species. Some eels live as few as six years, while others, like the European eel, can live for several decades. Research suggests that European eels can live up to 85 years in captivity, although they typically live around 20 years in the wild.

Are eels endangered?

Some eel species are indeed endangered. The International Union for Conservation of Nature (IUCN) lists the European eel as critically endangered due to factors like overfishing, habitat loss, pollution, and barriers to migration like dams. Conservation efforts are crucial to protect these unique species and their complex life cycles.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllThingsNature researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...
Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a AllThingsNature researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

Learn more...

Discussion Comments

anon18081

hey everyone,

i have a snowflake eel who is a little over a foot long. i've been feeding him/her krill, squid, shrimp, etc.. but nothing seems to fill him/he up!! i've even tried feeding him/her more often. does anyone have tips on how to keep my snowflake eel full?

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    • Many eels spawn in the Sargasso Sea, which is named for its copious amounts of Sargassum seaweed.
      Many eels spawn in the Sargasso Sea, which is named for its copious amounts of Sargassum seaweed.