One of the most general distinctions among organisms is between plants,
which use sunlight to make their own food, and animals, which consume energy-rich
foods. Some kinds of organisms, many of them microscopic, cannot be neatly
classified as either plants or animals.
| 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. |