● We are familiar with the `color{violet}("shape of a pyramid.")`

● The base of a `color{violet}("pyramid")` is broad and it narrows down at the `color{violet}("apex.")`

● One gets a similar shape, whether it is the `color{violet}("food or energy relationship")` between organisms at different trophic level that is expressed.

● Thus, relationship is expressed in terms of number, `color{violet}("biomass or energy.")`

● The base of each `color{violet}("pyramid")` represents the producers or the `color{violet}("first trophic level")` while the `color{violet}("apex")` represents `color{violet}("tertiary")` or top level consumer.

● The three `color{brown}("ecological pyramids")` that are usually studied are:

(a) `color{brown}("Pyramid of number")`

(b) `color{brown}("Pyramid of biomass")`

(c) `color{brown}("Pyramid of energy")`

● Any calculations of energy content, `color{violet}("biomass,")` or numbers has to include `color{violet}("all organisms")` at that trophic level.

● `color{violet}("No generalisations")` we make will be true if we take only a few individuals at any `color{violet}("trophic level")` into
account.

● Also a given organism may occupy more than one `color{violet}("trophic level")` simultaneously.

● One must remember that the `color{violet}("trophic level")` represents a `color{violet}("functional level")`, not a species as such.

● A given species may occupy more than one `color{violet}("trophic level")` in the same `color{violet}("ecosystem")` at the same time; for example, a sparrow is a primary consumer when it eats seeds, fruits, peas, and a secondary consumer when it eats insects and worms.

● In most `color{violet}("ecosystems")`, all the `color{violet}("pyramids,")` of `color{brown}("number")`, of `color{brown}("energy")` and `color{brown}("biomass")` are `color{brown}("upright")`, i.e., producers are more in number and `color{violet}("biomass")` than the `color{violet}("herbivores,")` and `color{violet}("herbivores")` are more in number and biomass than the `color{violet}("carnivores.")`

● Also energy at a `color{violet}("lower trophic level")` is always more than at a `color{violet}("higher level.")`

● There are exceptions to this `color{violet}("generalisation")`: In case we were to count the number of insects feeding on a big tree, the `color{violet}("pyramid ")`wouldn’t be `color{violet}("upright.")`

● The pyramid of `color{brown}("biomass in sea")` is also generally `color{brown}("inverted")` because the `color{violet}("biomass")` of fishes far exceeds that of `color{violet}("phytoplankton.")`



● `color{violet}("Pyramid")` of energy is `color{brown}("always upright ")`, can never be inverted, because when `color{violet}("energy flows")` from a `color{violet}("particular trophic level")` to the `color{violet}("next trophic level,")` some energy is always lost as heat at each step.



● Each bar in the `color{violet}("energy pyramid")` indicates the amount of energy present at each `color{violet}("trophic level")` in a given time or annually per unit area.

● However, there are certain `color{violet}("limitations")` of `color{violet}("ecological pyramids")` such as it does not take into account the same species belonging to two or more `color{violet}("trophic levels.")`

● It assumes a simple `color{violet}("food chain,")` something that almost never exists in nature; it does not accommodate a `color{violet}("food web. ")`

● Moreover,`color{violet}(" saprophytes")` are not given any place in `color{violet}("ecological pyramids")` even though they play a vital role in the `color{violet}("ecosystem.")`