Food chain
- Linear sequence of organisms through which nutrients & energy pass as one organism eats another. In a food chain, each organism occupies a different trophic level, defined by how many energy transfers separate it from the basic input of the chain.

Food Web
- Consists of many interconnected food chains & is a more realistic representation of consumption relationships in ecosystems.

TYPES OF FOOD CHAIN
Grazing food chain:
- It starts from living green plants, goes to grazing herbivores and on to carnivores.
- Ecosystems with such a type of food chain are directly dependent on an influx of solar radiation.
- Most ecosystems follow this type of food chain.
- Ex. Phytoplanktons →zooplanktons →Fish sequence or the grasses →rabbit →Fox.

Detritus food chain:
- It goes from dead organic matter into microorganisms and then to organisms feeding on detritus and their predators.
- Such ecosystems are less dependent on direct solar energy.
- These depend chiefly on the influx of organic matter produced in another system.
- Ex. Food chain operating in accumulated litter in a temperate forest.
- Ex. Earthworms, crabs, slugs or vultures.