The above pyramid represents:
(1) Pyramid of number of a parasitic food chain and pyramid of biomass of a pond ecosystem
(2) Pyramid of number of a pond ecosystem and pyramid of biomass of a forest ecosystem
(3) Pyramid of energy of a grassland and pyramid of biomass of an open ocean ecosystem
(4) Pyramid of biomass of a grassland and pyramid of number of a tropical forest ecosystem

Types of Ecological Pyramids

1. Pyramid of Numbers

• Definition: Shows the number of individual organisms at each trophic level.

• Upright: Most common, as producers (plants) are most numerous, followed by herbivores, then carnivores (e.g., pond, grassland, forest ecosystems).

• Inverted: Rare, but occurs in parasitic food chains, where a single host supports many parasites (e.g., a tree with many birds, which have many parasites)45.

2. Pyramid of Biomass

• Definition: Shows the total biomass (dry weight) at each trophic level.

• Upright: Most terrestrial ecosystems (grassland, forest); producers have the highest biomass.

• Inverted: Some aquatic ecosystems (open ocean, deep lakes); producers (phytoplankton) have less biomass than consumers (zooplankton)5.

3. Pyramid of Energy

• Definition: Shows the flow of energy through each trophic level.

• Always upright: Energy decreases at each trophic level due to losses as heat and metabolism25.

Matching Pyramids to Ecosystems

When answering questions about which pyramid represents which ecosystem, consider the following:

• Pond ecosystem:

  • Pyramid of numbers: Upright (many producers, fewer consumers).

  • Pyramid of biomass: Upright (producers have more biomass than consumers).

• Parasitic food chain:

  • Pyramid of numbers: Inverted (many parasites on a single host).

• Open ocean ecosystem:

  • Pyramid of biomass: Inverted (phytoplankton biomass less than zooplankton).

• Grassland/forest ecosystem:

  • Pyramid of numbers/biomass: Upright.

Example Question

Given a question about an ecological pyramid and four options describing which ecosystems or pyramid types it could represent, the correct answer is the one that matches the shape of the pyramid to the correct ecosystem or pyramid type.

For example, if the question asks which of the following the pyramid represents, and one option is:

(1) Pyramid of number of a parasitic food chain and pyramid of biomass of a pond ecosystem

This is correct because:

• Pyramid of numbers for a parasitic food chain is inverted.

• Pyramid of biomass for a pond ecosystem is upright.

This matches the scenario where one pyramid is inverted and the other is upright.

Conclusion

To answer questions about ecological pyramids, identify whether the pyramid is upright or inverted, and match it to the correct ecosystem or pyramid type. The pyramid of numbers for a parasitic food chain is inverted, while the pyramid of biomass for a pond ecosystem is upright.

Correct answer:
(1) Pyramid of number of a parasitic food chain and pyramid of biomass of a pond ecosystem