Within a decade or so, and some speculate for a much longer period, yellow eels undergo still another remarkable change, which includes developing special cells for riding their bodies of excessive sea salts and forming enlarged eyes. This prepares them for the long swim to the Sargasso Sea. Their yellow-green covering changes into a metallic sheen, with their backs turning purplish black. No longer freshwater creatures of the night, they have now become marine fish. From late summer to November, most silver eels leave inland waterways.
Males join females when the latter reach estuaries.
Together, during the dark phases of the moon, they follow the siren call that draws them home. By mid-winter, throngs of eels meet in the depths of the distant Sargasso Sea. After making this difficult voyage, they lay millions of eggs. Soon afterward, the silver eels die where they were hatched. Their offspring then begin this cycle anew.