Food Webs and Chains

Food Chains and Food Webs

• When multiple food sources are available, food chains branch out and form a food web, providing a complete picture of who consumes whom in an ecosystem.
• A food web represents the transfer of energy and nutrients among organisms in an ecosystem, while a food chain shows only one pathway.

Energy Flow in the Ecosystem

• Energy is necessary for all biological activities, and its transfer from one trophic level to another is called energy flow.
• Solar energy is transformed into chemical energy through photosynthesis, with only 1% of total light being utilized.
• Energy flows from the sun to plants and then to heterotrophic organisms, including consumers.

Food Chains

• Energy must pass from one living organism to another, with energy being transferred from plants to animals when herbivores feed on plants.
• At each linkage in the chain, a major part of the energy is lost for daily activities, with most chains having only four to five links.
• A single species may be linked to a large number of species, and food chains can be either Grazing (starting from green plants) or Detritus (starting from dead organic matter).

Trophic Levels

• Every biological community can have multiple and diverse food chains, but every food chain starts with a primary source of energy.
• Species can occupy more than one trophic level, with humans being an example of multilevel consumers or omnivores.
• Energy decreases successively at each trophic level, with only a small fraction (about 10%) going on to the next level.

Implications of Energy Flow

• The quantity of energy decreases rapidly from primary producers to the top consumer, explaining why food chains have fewer links.
• Supporting a larger human population on a vegetarian diet could be possible, as it involves one step in energy transfer, minimizing energy loss.