Food Chain

Food chain

A linear sequence of organisms through which nutrients and energy pass as one organism eats another. It shows the feeding relationships and the flow of energy within an ecosystem, always moving in a single direction from the sun to top predators.

Trophic levels

The feeding positions, or "steps," that organisms occupy in a food chain or food web. The word "trophic" comes from a Greek word meaning "nourishment" or "food." Every living organism belongs to a specific trophic level based on how it gets its energy.

Producers (Autotrophs)

Base of the chain. Plants, algae, and phytoplankton use photosynthesis to turn sunlight into chemical energy (glucose).

First-order Consumers (Primary Consumers)

Herbivores that eat producers (e.g., grasshoppers, rabbits, zooplankton).

Secondary Consumers

Carnivores or omnivores that eat primary consumers (e.g., frogs, snakes, small fish).

Tertiary Consumers

Apex predators that eat secondary consumers (e.g., hawks, lions, killer whales).

Decomposers

Organisms like fungi and bacteria that break down dead organic matter, returning vital nutrients back to the soil for producers to use again.

The 10% Rule of Energy

A fundamental law in ecology that dictates how energy flows through an ecosystem's trophic levels. It states that when energy is passed from one trophic level to the next, only about 10% of that energy is stored as biomass and made available for the next consumer. The remaining 90% is lost.

Food Web

A complex, interlocking network of all the food chains within a specific ecosystem. This shows the realistic reality of nature: most organisms eat, and are eaten by, multiple different species.