An ecological pyramid is a graphical representation of the number, biomass, and energy of the successive trophic levels of an ecosystem. In an ecological pyramid, the lowermost trophic level is formed by the producers and the topmost level is that of carnivores.
There are three types of pyramids:
⮚ Pyramid of numbers
⮚ Pyramid of energy
⮚ Pyramid of biomass Pyramid of numbers: It shows the association between the number of producers, herbivores, and carnivores. Depending on the number of producers, it can be upright or inverted. In a grassland ecosystem, grasses are the producers. The pyramid of numbers is often upright. In this type of food chain, the number of producers (plants) is followed by the number of herbivores (mice), which in turn is followed by the number of secondary consumers (snakes) and tertiary carnivores (eagles). Hence, At the producer level the number of individuals will be greatest, while at the top carnivores, the number of individuals present will be least.
Whereas on the other hand, in a parasitic food chain, the pyramid of numbers is inverted. In this type of food chain, several fruit-eating birds are provided with food by a single tree (producer), which in turn support several insect species.
Pyramid of biomass: A pyramid of biomass may be a graphical representation of the whole amount of living matter present at each trophic level of an ecosystem. It can be upright or inverted. The pyramid of biomass in grasslands and forest ecosystems is upright as the amount of biomass present at the producer level is higher than at the top carnivore level. In a pond ecosystem, the pyramid of biomass is inverted as the biomass of fishes far exceeds the biomass of zooplankton (upon which they feed).