Polarised light microscopy of the skin of an eel (Anguilla sp.). Unlike the well-developed scales on the surface of most other fish, eels have rudimentary cycloid scales which are embedded deeply within the skin. The scales develop only after the eel has spent about three years in fresh water. Overlying the scales are melanophores, control of the distribution of pigment within these structures acts as a camouflage mechanism. Magnification: x28 at 10cm wide. Magnification: x14 at 10cm wide.