The Six Classes of Components of Ecosystems

Primary Consumers

• Primary consumers are one class of an ecosystem. These include herbivorous organisms that feed on plants. Primary consumers may be larger mammals, such as herd animals, or they may be small rodents or even plant-eating insects. Many primary consumers both consume an ecosystem's flora and act as food sources for predatory carnivores, which make up the class of secondary consumers.

Secondary Consumers

• Secondary consumers feed on other animals. Secondary consumers are typically predators, which hunt and kill herbivorous primary consumers, and may be large or small. Lions and tigers are examples of large predators, whereas spiders and small carnivorous fish are examples of smaller secondary consumers. Some secondary consumers are scavengers, such as vultures, which eat the remains of animals that have already been killed by predators, disease or other natural causes.

Tertiary Consumers

• Tertiary consumers are omnivores, and will feed on both plants and animals. The most prominent example of tertiary consumers are humans, although other omnivores exist in some ecosystems. Bears, for example, eat both meat and vegetation, depending on availability.

Decomposers

• Consumers of decomposed organic tissue help to break down organic remains and return the nutrients therein to the soil. These include bacteria and fungi, which grow and reproduce on the remains of living matter. These members of the ecosystem are also called detritovores, and may grow on dead plant tissue or animal tissue.

Nutrients

• Nutrients are sometimes overlooked as a factor in ecosystems, because neither they nor their effects are readily apparent to the casual observer. Nutrients are a class of abiotic component, and include nitrates and phosphates present within an ecosystem's soil or water. Fats, proteins, vitamins and other trace elements also contribute to the overall nutrient content of soil and water.

Primary Producers

• The heat and light from the sun help both plants and animals to survive. In plants, sunlight is converted to energy via photosynthesis. This process allows plant life to grow and reproduce, providing food for the ecosystem's primary consumers. Because of its effect on plant life, sunlight is an important abiotic factor in determining which forms of life will live and thrive in any given ecosystem, and the plants which grow in its light are the more readily-observable biotic result.