Flexi Says: Energy enters ecosystems in the form of sunlight or chemical compounds. Some organisms use this energy to make food. Other organisms get energy by eating the food. Producers are organisms that produce food for themselves and other organisms. Most producers use energy from sunlight, along with matter from air and water, to make food molecules (sugars). This is the source of food in most ecosystems. In a few ecosystems, such as deep sea vents, producers make food using energy from chemical compounds, such as hydrogen sulfide.