Energy enters at the base of the food chain in the first trophic level (TL) via photosynthesis and is passed on to higher levels as consumers feed on other organisms. This is shown as a pyramid (smaller on top) because only a small percentage of the energy is passed on to each higher level, with the majority being “lost” to the environment (usually as heat from the energy that the organism burns in day-to-day life before it is eaten). Most food chains have only four or five levels due to this progressive loss of energy. Though the actual amount varies from ecosystem to ecosystem, for illustration purposes, we show 10% passing on to the next higher level.