Secondary consumers are organisms that eat primary consumers for energy. Primary consumers are always herbivores, or organisms that only eat autotrophic plants. Secondary consumers can either be carnivores or omnivores. Carnivores only eat other animals, and omnivores eat both plant and animal matter. Regardless of what a secondary consumer is, it still must have primary consumers in its diet to survive. Secondary consumers are an important part of the food chain as they control the population of primary consumers by eating them for energy. Secondary consumers also provide energy to the tertiary consumers.