Food chain

A sequence of organisms through which energy and nutrients pass as one organism consumes another. Each link represents a feeding relationship.

Trophic level: A position in a food chain or food web, defined by how an organism obtains energy. Each step in a chain marks a successive trophic level.
Predation: An interaction in which one organism kills and eats another. Predation creates many of the feeding links represented in a chain.
Food web: A network of interconnected feeding relationships among organisms in an ecosystem. Most organisms eat multiple species, so real feeding relations branch beyond one chain.
Trophic cascade in Yellowstone: A set of ecosystem changes associated with the return of gray wolves to Yellowstone National Park. The case illustrates how a top consumer can alter relationships down a feeding sequence.
Primary producer: An organism that builds organic matter from inorganic substances, usually using sunlight or chemical energy. Producers typically form the first living link by capturing energy.
Herbivory: An interaction in which an animal eats plants or algae. Herbivory links primary producers to animal consumers.
Ecological pyramid: A diagram showing the relative number, biomass, or energy of organisms at successive trophic levels. Pyramids compare whole trophic levels rather than tracing one feeding sequence.
DDT: A synthetic insecticide whose persistence and ecological effects led to restrictions in many countries. Its accumulation along food chains harmed predatory birds through biomagnification.
Consumer (biology): An organism that obtains energy by eating other organisms or organic matter. Consumers make up the links that pass energy onward through feeding.
Detritus: Dead organic material and waste that form a food source for decomposers and detritivores. Detrital feeding pathways begin with material shed or left by organisms.

Linked from 12 pages