What is a Food Pyramid?
A food pyramid, also known as an ecological pyramid, is a graphical model that illustrates the flow of energy through the different feeding levels of an ecosystem. It is shaped like a pyramid to represent the decrease in energy, biomass, or number of organisms at each successive level, starting with a wide base of producers and narrowing to a peak of top consumers.
Section 2: The Trophic Levels
A food pyramid is organized into trophic levels. The base consists of producers (like plants) that create their own food. The next level up contains primary consumers (herbivores) that eat producers. Above them are secondary consumers (carnivores or omnivores) that eat primary consumers, followed by tertiary consumers that eat secondary consumers. Decomposers, like bacteria and fungi, break down dead organic matter from all levels.
Section 3: A Practical Example
Consider a simple grassland ecosystem. Grasses are the producers at the bottom of the pyramid. Grasshoppers, which eat the grass, are the primary consumers. Frogs, which eat the grasshoppers, are the secondary consumers. Finally, hawks, which eat the frogs, are the tertiary consumers at the top. At each step, there is a significant loss of energy.
Section 4: Importance of the Food Pyramid
The food pyramid is important because it clearly demonstrates the principle of energy transfer in an ecosystem, often called the 10% rule. Only about 10% of the energy from one trophic level is incorporated into the next. This inefficiency explains why there are far fewer top predators than producers and why ecosystems require a constant input of energy from the sun.