Food-Web diagrams, showing the connections between organisms, are like road maps. Each feeding strategy is called a trophic level. As the source of energy for the system, producers are placed at the base of the diagram. Primary consumers eat producers. A grasshopper is a primary consumer because it eats grass leaves. Primary consumers may also be called herbivores. The garter snake that eats the grasshopper is a secondary consumer, or carnivore. The term "carnivore" can be confusing, however, because it also applies to the hawk that catches the snake. It's more accurate to say that the hawk is a third-level, or tertiary, consumer.