The study of how all plants and animals interact with each other in their non-living environment. The ecosystem includes plant and animal communities along with factors such as climate, altitude, temperature, moisture, light, and the chemical cycles. All the external factors to which an organism is exposed. Includes all abiotic and biotic factors that may influence the organism. A food chain describes the transfer of energy from one organism to another.
Food chains begin with the sun, the source of all energy on earth.
Since only plants can produce food from the sun's energy the first link in a food chain is always a plant. The second link in the chain is a plant eater and the third link a meat eater. The amount of stored energy is calculated by weighing all living things at each feeding level and the result is called a pyramid of biomass. A food web is a diagram which shows all the feeding relationships within a community. The diagram, which shows how the various food chains are interlinked, should include the scavengers, decomposers, and producers as well as the herbivores, omnivores, and carnivores.