Ecological Pyramids

An ecological pyramid is used to show different "levels" in an ecosystem. Sometimes the levels are called "trophic levels."

The base of the ecosystem are the producers/autotrophs. All other levels represent consumers. There must be more producers than consumers for an ecosystem to be stable. Each level of the pyramid directly supports the level above it. The second level of the pyramid represents herbivores, who directly rely on the producers for food. The third, fourth, and maybe even fifth level consumers represent predators. The top level represents the top predators of the ecosystem which are the "top of the food chain."

The pyramid also represents the amount of available energy in an ecosystem. As you move up the pyramid, the amount of available energy decreases. This is because at each level, there are less and less organisms. At each level, energy does not "build up." At each level, most of the energy obtained is lost to the environment as heat. This is because organisms don't "save" all of the energy that they obtain- they spend most of it. When organisms spend energy, it is lost to the environment as heat.