Food Chain

• The transfer of solar energy from the source i.e. green plants through a series of organisms by eating and being eaten constitutes the food chain.
• There are 4 parts in a food chain: Producers (plants), primary consumers (herbivores), secondary/tertiary & further consumers (carnivores) & decomposers (eat dead or decaying matter).
• At each transfer, a large proportion of the energy is lost in the form of heat.
• Also, at each stage, a lot of energy is lost on account of daily activities like respiration and metabolism.
• Each chain usually has 4 to 5 such links. However a single species may be linked to a large number of species.

Example 1:

Example 2:

Food Web

Each living thing in an ecosystem is part of multiple food chains. A food chain is a sequence of who eats whom in a biological community (or an ecosystem) to obtain nutrition. Each food chain is one possible path that energy and nutrients may take as they move through the ecosystem. All of the overlapping and interconnected food chains in an ecosystem make up a food web.

A food web is a graphical representation of feeding relationships among species in an ecological community, that is, of who eats whom. Typically, species are connected by lines or arrows called “links”, and the species are sometimes referred to as “nodes” in food web diagrams.

Organisms in food webs are organized into categories called trophic levels. There levels are divided into:

1. Producers (first trophic level) – Who make their own food and do not depend on any other organism for nutrition (eg. Plants)
2. Primary Consumers: Herbivores who eat plants, algae and other producers (eg. Mouse)
3. Secondary consumers that eat herbivores (Eg. Snake who eats mouse)
4. Tertiary consumers that eat secondary consumers (Eg. Eagle who eats a snake)
5. Decomposers (last trophic level) who eat non-living plant and animals remains (Eg. Fungi, Bacteria)

Food web is differs from a food chain in that the latter shows only a portion of the food web involving a simple, linear series of species (Eg. Predator, herbivore, plant) connected by feeding links. A food web depicts a more comprehensive picture of the feeding relationships and can be considered as a bundle of many interconnected food chains occurring within the community.