Grazing Food Chain (GFC) starts with green plants called producer at first trophic level. But in aquatic ecosystem, the GFC is the major channel for energy flow. In aquatic ecosystem, GFC begins with phytoplanktons which is producers. Detritus food chain (DFC) begins with dead organisms which is detritus. It starts with dead organic matter with decomposers called saprophytes at first trophic level, e.g. bacteria and fungi. In terestrial ecosystem, the major condition of energy flow is DFC.