Energy flow in an ecosystem
Energy flow is the flow of energy through various living organisms within an ecosystem. Every organism can be organized as a producer and consumer. The plants are producers and their energy is consumed by primary consumers (goat, cow, deer etc) and the primary consumer is consumed by secondary or tertiary consumers such as Lion, tiger etc.
Finally, when the tertiary consumer dies they are decomposed by microbes. The energy travels from plant to microbes and microbes to plants. This cycle of transfer of energy is called Energy Flow.
These producers and consumers can be organized into the food chains and food web. These food chains are organized into trophic pyramids
Energy flow is unidirectional
The arrows in the food chain show the energy flow is unidirectional, the head of the arrow indicates the direction of energy flow. In each step, the energy is lost in the form of heat.