* Producers are the base of the food chain. They are organisms like plants and algae that convert sunlight into chemical energy through photosynthesis. This energy is stored in their tissues.

* Consumers eat producers. They gain energy by consuming the producers. However, they don't get to keep all of the energy.

* Energy transfer is inefficient. Only about 10% of the energy from one trophic level (like the producer level) is transferred to the next trophic level (like the consumer level). The rest of the energy is lost as heat, used for metabolism, or goes to waste.

Example:

Let's say a plant stores 100 units of energy. A herbivore eating that plant will only get about 10 units of energy. A carnivore eating the herbivore will only get about 1 unit of energy. This pattern continues up the food chain.

Therefore, the higher up the food chain you go, the less energy is available.