Ecological pyramids are graphical (triangle-shaped) representations that show the relationship between different organisms (at different trophic levels) in terms of:
• Number (how many organisms),
• Biomass (total mass of living matter), or
• Energy (amount of energy flow).

They always start with producers at the base and move up to top consumers at the apex.

Pyramid of Number:

• Shows the number of individuals at each trophic level.
• It can be upright or inverted depending on the ecosystem.

Example:
• In a grassland ecosystem:
Many grasses → Fewer grasshoppers → Even fewer frogs → A few snakes → One eagle
(Upright pyramid)
• In a tree ecosystem:
One big tree → Many insects → Even more parasites
(Inverted pyramid)

Pyramid of Biomass:

• Shows the total mass (dry weight) of living matter at each trophic level.
• Usually upright, but can be inverted in some cases (like in aquatic ecosystems).

Example:
• In a forest ecosystem:
Large biomass of trees → Lesser biomass of herbivores (deer) → Still lesser biomass of carnivores (tigers)
(Upright pyramid)
• In a pond ecosystem:
Small biomass of phytoplankton → Larger biomass of zooplankton → Even larger biomass of fish
(Inverted pyramid)