Eel

Eels are elongated ray-finned fish in the order Anguilliformes, which includes about 1,000 species across many families.

Eels are elongated ray-finned fish in the order Anguilliformes, which includes about 1,000 species across many families. They are found in marine, estuarine, and freshwater habitats, and many species have complex life cycles that include a larval ocean phase and major migrations. Eels are not a single species but a diverse group including freshwater eels, conger eels, moray eels, and deep-sea forms.

Classification and diversity

Eels are ray-finned fishes in the order Anguilliformes. The group is diverse, with roughly 1,000 species placed in multiple families, including Anguillidae (freshwater eels), Congridae (conger eels), and Muraenidae (moray eels).

Physical characteristics

Eels typically have long, slender bodies and a snake-like appearance. Many species have small or reduced pelvic fins and a continuous fin arrangement that helps them move through water.

Life cycle and migration

Many eel species have a leptocephalus larval stage in the open ocean, followed by metamorphosis into a juvenile form. Some, especially freshwater eels, are catadromous, meaning they live in freshwater but spawn in the sea, migrating long distances between marine spawning areas and inland habitats.

Habitats and ecology

Eels live in oceans, estuaries, lakes, and rivers depending on the species. They are usually carnivorous and often function as both predator and prey in aquatic ecosystems, feeding on smaller fish and invertebrates.