Define ecological pyramids and describe with examples pyramids of number and biomass.

Explanation

It is a graphical representation of the trophic structure and function of an ecosystem. The base of each pyramid represents the producers of the first trophic level, while the apex represents the tertiary or top level/top order consumers. The three types of ecological pyramids that are usually studied are (a) pyramid of number (b) pyramid of biamass and (c) pyramid of energy. These pyramids were first represented by Elton, hence the name ELTONIAN pyramids / Ecological pyramids.
Any calculations of energy content, biomass or numbers has to include all organisms at that trophic level. No generalizations we make will be true if we take only a few individuals of any trophic level into account. In most ecosystems, all the pyramids - of numbers, energy and biomass are uprights. i.es, producers are more in number and biomass than the herbivores, and herbivores are more in number and biomass than the carnivores. Also energy (available) at a lower trophic level is always more than that at a higher level. .
There are exceptions to this generalization. In the case of a parasitic food chain, the pyramid of numbers is inverted. A large tree (single producer) may support many herbivores like squirrels and fruit eating birds. On these herbivores many ectoparasites such as-ticks, mites and.lice (secondary consumers) may live. These secondary consumers may support many more top level consumers and also the hyperparasites. Thus in each trophic level from the bottom to the top, the numbers of organisms increase and forin an .inverted pyramid. of numbers.
The pyramid of biomass in sea is also generally inverted because the biomass of fishes far exceeds that of phytoplankton.