The European eel (Anguilla anguilla) has a very unusual and fascinating life cycle. Adults have long, narrow bodies, with a continuous dorsal, anal and tail-fin. The skin is slimy, the lower jaw is longer than the upper jaw, and the scales are tiny or absent. The colour of adults depends on their age; they are often brown, black or olive-green with yellowish bellies. Some adults may be silvery (known as 'silver eels'); the lifecycle stages differ greatly in appearance.