Let us begin with two caveats. Energy pyramid is not exactly similar to the food chain. While there are similarities between an energy pyramid and a food chain, the latter includes many factors. An energy pyramid is strictly confined to the energy produced, consumed and released. It doesn’t really delve into the reasons why a certain food chain or the pyramid itself is designed that way.
Energy Pyramid: Definition
An energy pyramid is a diagram or a graphical representation of how energy is produced and how it flows from one group to another or one organism to another. An energy pyramid can be used to depict a food chain, it may be used to depict the various processes in a chemical equation and it may also be used to illustrate or depict a natural process of energy conversion and transmission in a graphical way.
Let us confine our discussion to food chain or energy producers and consumers. It is well known that only one form of life can produce their own food and is thus the energy producers. These producers can generate energy from nonliving elements in the ecology. These producers are also the ones that introduce the energy in the community of consumers. The producers are the plants and some single celled microorganisms that can make their own food.
The producers form the absolute bottom level of the energy pyramid. The second level from the bottom is of primary consumers who obtain energy from the producers. In other words, the primary consumers are herbivores as they feed on plants, fruits and vegetables. The third level from the bottom is of secondary consumers. These feed on the primary consumers. These are carnivores as they feed on living organisms. The fourth level from the bottom which is usually the topmost level at the tip of the pyramid feed on secondary consumers.
The number of levels can vary depending on the food chain. If humans are factored in along with all animals in the world, then the food chain would have more than ten levels. If only plants, fishes and birds are taken into consideration then four levels would be sufficient for the energy pyramid.
One may wonder why it is called an energy pyramid and why the graphical representation is in the form a triangle or pyramid. The reason is that every level upward, there is a decline in available and useful energy. The producers are the richest sources of energy, then the primary consumers and finally the secondary consumers. Tertiary consumers have very little energy left in them to become food or source of energy for another level.