An ecological pyramid is a graphical representation that shows the relationship between different organisms in an ecosystem at various trophic levels. It depicts the flow of energy or biomass or the number of organisms from producers to top-level consumers. The base of the pyramid is always the producers, and the top is top-level carnivores.

Types of Ecological Pyramid

There are three major types of ecological pyramids commonly studied in biology:

1.Pyramid of Number

2. Pyramid of Biomass

3. Pyramid of Energy

Pyramid of Number

A pyramid of numbers focuses on the count of individual organisms at each trophic level. Typically:

(i) The base (the widest level) is occupied by producers (like plants or algae), which are often extremely numerous.

(ii) The next level is formed by primary consumers (herbivores), followed by secondary and tertiary consumers.

Pyramid of Biomass

The pyramid of biomass compares the total dry weight (or living organic matter) of organisms at each trophic level. Here:

(i) Producers usually form the heaviest bulk of living matter in an ecosystem, so they create a broad base.

(ii) Consumers tend to have less total biomass at higher trophic levels.

Pyramid of Energy

A pyramid of energy shows the flow of energy at different trophic levels within a specified period, often measured in kilocalories (kcal) or joules (J). This is the only type of ecological pyramid that is always upright because energy flows in a single direction—from producers up to various levels of consumers—and at each transfer, some energy is lost as heat.

(i) First Trophic Level (Producers): They capture energy from the sun (via photosynthesis) or chemicals (via chemosynthesis).

(ii) Higher Trophic Levels (Consumers): Herbivores, carnivores, and omnivores derive energy by feeding on organisms at lower levels. At each step, around 10% (the “10% law” described by Raymond Lindeman) of the energy is passed on to the next level, while the rest is lost primarily as heat or through metabolic processes.