A food chain or more correctly, a food web, is a succession of organisms in an ecosystem that serves as continuation of food energy. An organism "lower" in food chain is a source of food energy (is consumed) for another organism on a "higher" level.

Example of a "food chain":

algae --> protists --> squid --> seal --> orca

In contemporary research the term food web rather than food chain is usually used. This is a more accurate description when looking at the more complex nature of food chains, that is most animals feed on more than one source. The relationship between organisms is underlined.

The line Phytoplankton --> Herbivorous Zooplankton --> Carnivorous Zooplankton --> Arctic Char --> Chapelin at the right hand side of Fig. 1 is a food chain.

See also: trophic level