In the world of nature, we find a complex system called a food chain. Each participant in this chain is out to dinner, so to speak, but who is ordering what and why? A food chain represents how nutrients and energy are passed from one organism to another. Organisms in an ecosystem are divided into levels based on what they eat and who eats them. These levels are called trophic levels.Producers are at the very bottom of the food chain. They are plants that have a unique ability to make their food using sunlight. For instance, shrubs and trees are producers in a forest ecosystem. They are the number one source of food – think of them as the chefs in our dining analogy!Next comes the herbivores, known as Primary Consumers. They only eat plants, so they love the meals our producer chefs prepare! Deer in a forest ecosystem are a perfect example of a primary consumer. Then, we have Secondary Consumers. These guys eat the primary consumers, or the herbivores. They are carnivores or omnivores (eating both plants and animals). An example here is a fox that loves to savor deer or rabbits.Finally, at the top of the food chain are the Tertiary Consumers, or the apex predators. These fearsome feasters have no natural predators. In the forest, a bear is a good example!In addition to these, there's a special detailed map of energy transfer known as a food web - because nature is complex and rarely orderly. Organisms don't just eat one type of food, but may eat multiple types and thus belong to multiple chains.