Definition

A food web is a map of many food chains joined together, showing that most animals eat more than one thing and are eaten by more than one thing, such as a mouse eating seeds and insects while being hunted by hawks, foxes, and snakes, so losing that one mouse population would take a meal away from all three predators at once. More formally, a food web diagrams all the feeding relationships in an ecosystem, made of many interconnected food chains with arrows pointing from each organism to whatever eats it, and because most consumers feed on and are eaten by several species, food webs are more realistic than single chains, and webs with many connections tend to be more stable, since a consumer with several food options can switch if one source fails. At the network level, a food web represents trophic interactions as nodes for species or functional groups and directed links for energy or biomass flow, described by connectance, link density, and the distribution of trophic levels, with quantitative webs weighting links by flux; theory and experiment show that a distribution of many weak links and a few strong ones promotes stability, and that omnivory and the coupling of grazing and detrital pathways buffer ecosystems against fluctuation, while removing highly connected species or top predators can cause secondary extinctions and trophic cascades.