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Concept
Anguillidae
Résumé
The Anguillidae are a family of ray-finned fish that contains the freshwater eels. Eighteen of the 19 extant species and six subspecies in this family are in the genus Anguilla, and all are elongated fish of snake-like bodies, with long dorsal, caudal and anal fins forming a continuous fringe. They are catadromous, spending their adult lives in freshwater, but migrating to the ocean to spawn.
Eels are an important food fish and some species are now farm-raised, but not bred in captivity. Many populations in the wild are now threatened, and Seafood Watch recommend consumers avoid eating anguillid eels.
Adult freshwater eels are elongated with tubelike, snake-shaped bodies. They have large, pointed heads and their dorsal fins are usually continuous with their caudal and anal fins, to form a fringe lining the posterior end of their bodies. They have relatively well developed eyes and pectoral fins compared to saltwater eels that they use to navigate and maneuver through river bottoms and shallow water. Unlike most eels, freshwater eels have not lost their scales, and instead have soft, thin, scales that are embedded in the epidermis. Additionally, freshwater eels possess small, granular teeth arranged in bands on the jaws and vomer. Anguillidae do exhibit size-dependent sexual dimorphism. Male anguillids invest more energy into mating with as many females as he can, than they do into growth. Therefore, female anguillids are usually larger, ranging from 1.5 – 3 feet, while male anguillids rarely get larger than 1.5 feet long. Adult anguillidae can vary in color, but normally are brown, olive or olive-yellow, and can be mottled. Coloration matches the floor of rivers and lakes which prevents the eels from being seen by predators while in clear or shallow water. Freshwater eels go through physical changes in their bodies when going to and from the ocean for different stages of life.
There are two important fossils used to date the origin of freshwater eels.
Source officielle
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