All organisms, including the human species, are part of and depend on
two main interconnected global food webs. One includes microscopic ocean
plants, the animals that feed on them, and finally the animals that feed
on those animals. The other web includes land plants, the animals that
feed on them, and so forth. The cycles continue indefinitely because organisms
decompose after death to return food material to the environment.
NSES Content Standard C
Life Science: Populations and ecosystems Grades 5-8, page 157 Populations of organisms can be categorized by the function they serve in an ecosystem. Plants and some micro-organisms are producers--they make their own food. All animals, including humans, are consumers, which obtain food by eating other organisms. Decomposers, primarily bacteria and fungi, are consumers that use waste materials and dead organisms for food. Food webs identify the relationships among producers, consumers, and decomposers in an ecosystem. |