A food chain is a linear sequence of links in a food web starting from a tropic species that eats no other species in the web and ends at a tropic species that is eaten by no other species in the web. A food chain differs from a food web, because the complex polyphagous network of feeding relations are aggregated into trophic species and the chain only follows linear monophagous pathways. A common metric used to quantify food web trophic structure is food chain length.
