Eel

Although these creatures are very snakelike in appearance, they are actually fish. They are ray-finned fishes of the order Anguilliformes, with the term “eel” referring to snakelike fish such as electric, ribbon, wolf eels, lampreys, and morays, along with true eels for a total of 800 species. Eels can range in length from a few inches to over 13 feet. The body of an eel has a slimy coating, hence the phrase, “Slippery as an eel.” A few freshwater species have become endangered due to human overconsumption. The most dangerous species of eel is the conger.

Classification and Scientific Name

Anguilliforms include freshwater as well as saltwater fish such as marine morays. There are 19 families, 111 genera, and approximately 800 species. They are further classified from the Phylum Chordata into the Actinopterygii Class. They are also Teleosts, or members of the infraclass Teleostei, which contains 96% of all currently existing fish species.

Conger or true eels (Conger conger) are members of the family Congridae, which includes both congers and garden eels. Only members of the order Anguilliformes are true eels. The electric eel is not a true eel but a knifefish, related to carp and catfish, and a member of the order Gymnotiformes and the genus Electrophorus. It is also an air breather and, unlike true eel species, lives in freshwater.

The wolf eel‘s scientific name is Anarrhichthys ocellatus. The scientific name of the ribbon eel, also known as the leaf-nosed moray or bernis, is Rhinomuraena quaesita. Morays are of the family Muraenidae; however, the ribbon eel is sometimes classed in its own family, Rhinomuraenidae. Lampreys are jawless fish of the class Hyperoartia, order Petromyzontiformes, and superclass Cyclostomata.

Evolution

The ancient ancestors of modern eels first appeared around 140 million years ago. For a long time, the intricacies of how these creatures developed into the complex array of species we find around the globe today were a complete mystery to the scientists who studied them. However, with the vast advancements made in genetic coding, many of the eel’s secrets have been revealed.

While examining the DNA of American and European eels, researchers found that it was around 2.5 to 3.5 million years ago, during the formation of the Isthmus of Panama between North and South America, that these two major groups of eels became separate from one another and began to develop their own distinct traits.

Appearance

Different species vary in appearance by their length, color, mouth, and fins. For example, wolf eels are a species of wolffish that differs from true species of eels with their paired gill slits and pectoral fins, while the lamprey has a toothed, funnel-shaped mouth. However, all have long, snakelike or wormlike bodies that end in a modified tail fin that is really the fusion of the dorsal and anal fins.

They are also characterized by strong jaws and small, sharp teeth. These fish have no pelvic fins and many lack pectoral fins. The larvae are called glass eels, so named due to their transparency. The term does not refer to a fish species, but the larval stage refers to the fish’s life stage after hatching and up to adulthood.

Distribution, Population, and Habitat

The population of all 800 species worldwide is unknown. They can inhabit a small or large range because each species has its own unique distribution. Eel fish can inhabit many types of habitats, including oceans, rivers, lakes, and smaller bodies of water. They live deep underwater so as to burrow into the ocean floor or find shelter in coral reefs, rock fissures, and muddy or pebbly water. Fish of the family Anguillidae typically inhabit freshwater.

Predators and Prey

American and European species are threatened by habitat destruction and climate change. Overconsumption by humans is responsible for endangering American and Japanese species and critically endangering the European species.

What eats eels?

There are several types of predators, depending on the species and its size. Generally, larger fish, seabirds (including herons and storks), and mammals (including raccoons and humans) eat these fish.

What do eels eat?

Eels are primarily predatory fish with carnivorous diets and are sometimes cannibalistic. They eat smaller fish, invertebrates, crustaceans, shrimp, crabs, and sea urchins. Those in freshwater habitats also consume insect larvae, including mosquitoes, and worms. Freshwater species eat carrion in addition to live prey.

Reproduction and Lifespan

These fish reproduce in large mating groups, in which they swim around each other to spawn. After spawning, the eggs hatch into larvae called glass eels. After the adults spawn, they die. Freshwater species will go to marine waters to mate. However, not much else is known about their reproduction.

The lifespan of these fish generally ranges from 32 to 88 years, depending on the species. On the low end, the short-finned species lives 32 years. The American species lives 43 years, and the European species is the longest-living at 88 years.

Eel in Fishing and Cooking

The main commercial types are the American (Anguilla rostrata), European (Anguilla anguilla), Japanese (Anguilla japonica), and the short-finned eel (Anguilla australis). All of them are freshwater fish (family Anguillidae). A popular saltwater species in Japanese cuisine is the white-spotted conger (Conger myriaster).

Population

Determining this fish’s population is dependent on each species, as a worldwide assessment of all 800 species has not been done. The IUCN status of the American and Japanese species is both Endangered, while the European species is Critically Endangered. The short-finned species has not yet been assessed.

Eel Species

There are over 800 species, including snakelike fish and true eels. Conger, electric, fire, and muraena are the most dangerous species. The conger and muraena have powerful jaws with sharp teeth strong enough to drag people, while several shocks from an electric eel can cause respiratory or heart failure in people with underlying heart issues. The fire eel has toxic skin.