The three types of ecological pyramids include the pyramid of numbers, the pyramid of energy and the pyramid of biomass. These pyramids may be upright, inverted or partly upright, depending on the number of organisms on a given level. Regardless of the shape, the producers are always on the bottom.
The pyramid of numbers depicts the number of organisms at each level of an ecosystem, and what the ecosystem is determines the overall shape of the pyramid. A number pyramid for the ecosystem involved in a tree in the forest has a different shape than one for the grassy plains of the Serengeti.
The pyramid of energy depicts the flow of energy, measured in calories, from one level to the next. This pyramid is always upright because of the loss of energy as each level consumes the lower one.
The biomass pyramid depicts the amount of organic matter found on each level of the ecosystem. Again, the shape of the pyramid is different for different ecosystems. While the amount of plankton and aquatic plants is greater than the number of sharks in the ocean, the weight of the sharks is much larger than the plankton, which makes for an inverted pyramid. In the forest, where trees and other plant life are large and heavy compared to the weight of the carnivores that live there, the pyramid is upright.