Here's why:

* Producers: Plants are the base of the food chain. They capture energy from the sun through photosynthesis and convert it into chemical energy stored in their bodies.

* Consumers: Animals eat plants or other animals, obtaining the chemical energy stored in their prey.

* Decomposers: Organisms like bacteria and fungi break down dead organisms and waste, releasing nutrients back into the ecosystem.

Important note: Only a portion of the energy from one trophic level (e.g., plants) is transferred to the next trophic level (e.g., herbivores). This is because some energy is lost as heat during metabolic processes. This is why food chains typically have only 4-5 levels, as the amount of energy available decreases significantly with each step.