Primary consumers are organisms that eat producers, which are typically plants or algae. They play a crucial role in the food chain by converting the energy stored in these producers into a form that can be used by higher-level consumers. Examples of primary consumers include herbivores like rabbits, deer, and caterpillars. These consumers are essential for maintaining the balance of ecosystems. By feeding on producers, they help control plant populations and provide energy for secondary consumers, such as carnivores and omnivores. This interconnectedness highlights the importance of primary consumers in sustaining biodiversity and ecosystem health.