Primary consumers are organisms that consume producers for energy and nutrients. The producers in many recognizable ecosystems are plants and the primary consumers are the herbivorous animals that consume the plants.
An ecosystem requires a constant input of energy since energy is lost through life processes and as the energy is passed through the trophic levels of the ecosystem. Photosynthesis is the method used by plants and algae to use sunlight to meet their energy demands and the surrounding ecosystems.
Energy and nutrients are passed between different trophic levels of the ecosystem through consumption. The organisms occupying each level can be classified as primary producers, primary consumers, secondary consumers or tertiary consumers.
Primary producers include plants, algae and microscopic organisms that capture energy and uptake nutrients from their surroundings. Primary producers are often referred to as autotrophs since they make their own food.
Primary consumers consume primary producers to meet their energy and nutrient needs. Examples of primary consumers range from aphids to zebras.
Secondary consumers eat primary consumers to gain the energy and nutrients they require. For example, ladybugs consume aphids and lions prey on zebras.
Tertiary consumers are the top predators for their ecosystem, preying on other predators for their nutrient needs. Eagles preying on predatory fish are an example of tertiary consumers.
