Food web
A food web is a network of feeding relationships in an ecosystem. It shows how energy and matter move among producers, consumers, decomposers, predators, prey, parasites, scavengers, and detritus pathways rather than through a single simple food chain.
What a food web is
A food web is a map of who eats whom in an ecosystem. It links many food chains together because most organisms eat more than one thing and are eaten by more than one predator, parasite, or decomposer. Food webs are used in ecology to understand energy flow, nutrient cycling, species interactions, and ecosystem change.
Food chain versus food web
A food chain is a simple line, such as grass to grasshopper to frog to snake. A food web is closer to real life. The grasshopper may eat several plants, the frog may eat many insects, the snake may eat frogs and small mammals, and decomposers process dead material from every level. The web shows overlap, alternatives, and indirect connections.
Producers and energy entry
Most food webs begin with primary producers: plants, algae, phytoplankton, or microbes that make organic matter from sunlight through photosynthesis. In some dark environments, such as deep-sea vents, chemosynthetic microbes use chemical energy instead. Producers are the base because they convert outside energy into food that other organisms can use.
Consumers and trophic levels
Consumers get energy by eating other organisms or their products. Herbivores eat producers, carnivores eat animals, omnivores eat both plants and animals, and predators can occupy different trophic levels at different life stages. Trophic levels are useful shorthand, but many species do not fit neatly into a single level.
Decomposers and detritus
Dead leaves, carcasses, waste, shed skin, and dissolved organic matter do not leave the web. Bacteria, fungi, worms, insects, scavengers, and detritivores break them down and return nutrients to soil, water, and living organisms. In many ecosystems, the detritus pathway carries a large share of energy and matter.
Stability and change
Food webs help explain why ecological change can spread. Removing a predator may release prey populations; losing a producer can reduce food for many consumers; adding an invasive species can redirect energy and competition. Some webs have enough redundancy to absorb change, while others are sensitive to the loss of a key species or link.
Human impacts
Fishing, hunting, farming, pollution, habitat loss, warming, acidification, invasive species, and nutrient runoff can all alter food webs. The effects are not always direct. A chemical pollutant may concentrate in higher-level predators, a warmer ocean may shift plankton timing, or a missing herbivore may allow one plant group to dominate.
Why it matters
Food webs turn biodiversity from a list of species into a set of relationships. They help conservationists, fisheries managers, farmers, public-health researchers, and climate scientists ask practical questions: which connections keep a system working, which species are vulnerable, and what might happen when conditions change.