Aquatic animals contain various carotenoids that exhibit structural diversity. These carotenoids originate from algae or partly from some bacteria. Herbivorous animals directly ingest carotenoids from dietary algae and metabolize them. Carnivorous animals ingest carotenoids from dietary herbivorous animals and metabolize them. Therefore, carotenoids found in these animals reflect the food chain as well as the metabolic pathways. Carotenoids in aquatic animals are described from the viewpoints of natural product chemistry, metabolism, food chain, and chemosystematics.
Keywords: Aquatic animals; Carotenoids; Chemosystematics; Food chain; Metabolism.