Autotrophs are quite simply defined as automatic-trophic organisms; they produce their own chemical energy. Most autotrophs undergo a process called photosynthesis, which by collection of  reactants: sunlight energy, water, and carbon dioxide they producglucose-- a simple sugar, OR chemosynthesis-- where carbon dioxide, oxygen, water, and hydrogen sulfide expelled by hydrothermal vents, meant to replace sunlight energy, produce another simple sugar. These autotrophic organisms vary throughout the six taxonomic kingdoms.
 Let's explore some examples of marine autotrophs!