Food chains and Food webs

Food Chains

• A food chain describes how energy and nutrients move through an ecosystem. It basically shows who eats what in the ecosystem. Thus, the transfer of energy from the source in plants through a series of organisms by eating and being eaten constitutes food chains.
• At each transfer, a large proportion of energy is lost in the form of heat.
• At each linkage in the chain, a major part of the energy from the food is lost for daily activities.
• Each chain usually has only four to five such links. However, a single species may be linked to a large number of species.

Food Chains are generally classified into two: A grazing food chain and a detritus food chain

1. Grazing food chain: It includes eating of a plant by an animal and eating of an animal by another. The food chain always starts with the green plants.

Example:

2. Detritus Food Chain: It starts from dead organic matter (detritus) and goes through decomposers (bacteria, fungi) to the detritus feeders (earthworms) and then to carnivores feeding on them.

Example:

The food chains show simple and isolated feeding relationships. Such simple relationships do not or rarely occur in ecosystems. In reality, all the food chains are interconnected. All of the interconnected and overlapping food chains in an ecosystem form a food web.

Food Web:

• These food chains are not isolated sequences, but are interconnected with each other. This interlocking pattern is known as the food web.
• Impact of human interference: If the linkages in the chains that make up the web of life are disrupted due to human activities that lead to the loss or extinction of species, the web breaks down.