European glass eels use internal magnetic compass to navigate waters

The video discusses a study on European eels, revealing their use of an internal magnetic compass to navigate tidal waves during migration. These eels hatch in the Sargasso Sea and travel to Europe's continental slope, undergoing various life stages. A scientific study observed glass eels' response to magnetic fields, suggesting this mechanism aids in navigation when visual cues are absent. This magnetic sense may also guide mature eels back to the Sargasso Sea for spawning.

What happens to eels when they reach the adult stage, and how does their color change?

Explain the role of visual reference points for eels during their upstream migration.