Final answer:
An ecological pyramid illustrates energy, biomass, or number of organisms across trophic levels in an ecosystem. Energy flow starts at producers with the greatest energy and biomass, decreasing through each trophic level of consumers. With producers at the base, only about 10% of the energy is transferred to each subsequent level, resulting in lesser energy and biomass at higher levels.
Step-by-step explanation:
Basic Ecological Pyramid Description
An ecological pyramid, also known as an Eltonian pyramid, is a graphical representation that illustrates the energy flow, biomass, or number of organisms in each trophic level within an ecosystem. At the base of this pyramid are the producers, which are autotrophic organisms such as plants that capture energy from the sun through photosynthesis. Above the producers are various levels of consumers, which include primary, secondary, tertiary, and quaternary consumers. Primary consumers are herbivores that eat the producers. Secondary consumers are carnivores that prey on the primary consumers, and so on.
Energy flow in the ecological pyramid works in a way where each trophic level receives energy from the level below it but can only pass on about 10% of that energy to the next level due to energy being lost as heat and through metabolic processes. This 10% rule means that if producers have 1,000,000 kilocalories of energy, then primary consumers would have access to only 100,000 kilocalories of that energy. The subsequent levels would then have access to progressively less energy—10,000 kilocalories for secondary consumers and 1,000 for tertiary consumers. The decline in energy available at each trophic level leads to fewer organisms and less biomass as one moves up the pyramid.
Biomass is the total mass of organisms at a given trophic level, and it tends to decrease from lower to higher levels. The largest biomass is found at the level of the producers, and it declines as you move up to the quaternary consumers, which have the least biomass. This decrease in biomass is due to the lesser energy available at higher levels, restricting the number of large organisms that can be supported.