Food web
Say it: FOOD WEB
A food web is the network of interconnected food chains in an ecosystem, showing the many feeding links through which energy and nutrients pass.
Also: food webs
Definition
What is a food web?
A food web is a model of who eats whom in an ecosystem. It is built from many overlapping food chains, each a single linear path along which energy and nutrients pass from one organism to the next, such as grass to rabbit to fox. Because most organisms eat more than one kind of food and are eaten by more than one predator, real feeding relationships form a web rather than a line, which makes a food web a more realistic picture of an ecosystem than any single chain.
Food webs are organized into trophic levels. Producers such as plants and phytoplankton form the base, herbivores eat them, and carnivores and omnivores feed higher up, with apex predators at the top. Ecologists often distinguish a grazing food web, which starts with living photosynthetic organisms, from a detrital food web, which starts with dead organic matter eaten by decomposers and detritivores. The two are usually linked.
Mapping a food web shows how a change in one population ripples through others. Losing sea otters, for example, lets sea urchins multiply and strip kelp forests bare. Food webs also explain biomagnification, the build-up of persistent toxins such as DDT and mercury in top predators.
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Terms that go with it
- Trophic levelA trophic level is a feeding position in a food chain, such as producer, herbivore or carnivore, defined by how an organism obtains its energy.
- EcosystemAn ecosystem is a community of living organisms together with the nonliving environment they interact with, linked by energy flow and nutrient cycling.
- DecomposerA decomposer is an organism, mainly a bacterium or fungus, that breaks down dead organisms and wastes and returns their nutrients to the environment.
- Keystone speciesA keystone species is one whose effect on its ecosystem is far larger than its numbers suggest, so that removing it reshapes the whole community.
- PhotosynthesisPhotosynthesis is the process in which plants, algae and cyanobacteria capture light energy and store it in sugar built from carbon dioxide and water.
- PlanktonPlankton are organisms that drift in oceans, lakes and rivers because they cannot swim against currents, from microscopic algae to large jellyfish.
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Written for biofideX in plain words, after checking these references:
- OpenStax Biology 2e, 46.1 Ecology of Ecosystems
- National Geographic Education: Food Web
- OpenStax Biology 2e, 46.2 Energy Flow through Ecosystems
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