Example of a food chain:
algae --> protists --> squid --> seal --> orca
Sometimes the term food web rather than food chain is 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 the illustration below is a food chain.
Example food web