What happens to energy as it moves from one trophic level to the next?

• A. Energy is created at higher levels
• B. Energy remains the same at all levels
• C. Energy decreases at each trophic level, with less available to higher levels
• D. Energy accumulates in top predators

Answer: (C)

Energy moves through an ecosystem in one direction from the sun to producers and then to consumers. When organisms use energy for life processes like moving, growing, and keeping body temperature, much of that energy is lost as heat and can’t be stored for the next level. Only a portion is stored in the tissues of an organism and becomes the energy that the next trophic level can use. Because of this ongoing loss, the amount of usable energy available gets smaller at each step up the food chain. That’s why there are usually many plants, fewer herbivores, and even fewer carnivores higher up—the energy available to support organisms decreases as you go up. A common idea to remember is that roughly about ten percent of the energy at one level moves on to the next, with the rest lost as heat or used in metabolism. So energy decreases at each trophic level, with less energy available to higher levels.