Biology: How Energy Flows from Grass to Fox

Every ecosystem runs on energy, and food chains are the simplest way to trace where it comes from and where it goes. At the base sits the producer, an organism like grass that captures sunlight and builds its own food through photosynthesis. From there, energy passes along a single linear pathway as each consumer eats the one before it. This matters because energy transfer explains why ecosystems are structured the way they are: only a fraction of the energy at one level reaches the next, so food chains rarely stretch beyond four or five links. In the chain grass → rabbit → fox, energy begins in the grass, moves to the rabbit when it feeds on the grass, and continues to the fox when it eats the rabbit. The arrow always points in the direction of energy flow, from the organism being eaten to the one that eats it.