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How is sex determined in European freshwater eels?
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eel
The American eel (Anguilla rostrata) is found in habitats along the coast of eastern North America.
In the European freshwater eel (Anguilla anguilla), sex is determined primarily by environmental factors rather than being fixed at fertilization.1
Before reaching their definitive sex, these eels pass through successive developmental phases, including neutrality, precocious feminization, and juvenile hermaphroditism. During these stages, the influence of the environment dictates whether an individual will ultimately develop into a male or a female.1