Fallen leaves are the remnants of plants. Earthworms eat fallen leaves and are decomposers. Chickens should be consumers. Animals that eat decomposers generally belong to consumers in the food chain.

Consumers belong to heterotrophs, referring to those animals that feed on other organisms or organic matter, and they directly or indirectly feed on plants.

Parasites are special consumers and can be regarded as herbivores or carnivores according to their feeding habits. However, some parasitic plants, such as mistletoe and mistletoe, belong to producers because they can make their own food. Omnivorous consumers are between herbivores and carnivores, eating both plants and animals, such as carp and bears. Human food is also omnivorous. These different levels of consumers get food from different organisms, forming a "nutrition level".

The decomposer is also heterotrophs, mainly various bacteria and fungi, including some protozoa and saprophytes such as beetles and termites that feed on dead wood, as well as earthworms and some mollusks. They decompose complex animal and plant residues into simple compounds, and finally into inorganic substances, which return to the environment and are reused by producers. Decomposition is of great significance in material circulation and energy flow, because about 90% of the primary production on land must be returned to the earth through decomposition, and then transferred to green plants for photosynthesis. So decomposers can also be called reducers.