What is an Inverted pyramid of biomass?

Know in one minute about the inverted pyramid of biomass

  • The inverted pyramid of biomass shows the biomass of an organism in each trophic level of the food chain.
  • It is inverted because the amount of biomass is high in consumers and low in producers.
  • Here several generations of phytoplankton are thus consumed by a single generation of zooplankton.
  • In the inverted pyramid of biomass, the biomass of fish is large because fish have long life spans.
  • During transformation, only 10% of the biomass of the organism passes to the next trophic level.
  • In this case, the top of the pyramid is wide and the bottom of the pyramid is narrow.
  • An inverted pyramid of biomass formed in a degraded ecosystem because here primary producers are few and primary consumers are high.
  • In this pyramid, shorter food chains are seen with many organisms at higher levels.
  • Here the biomass amount of consumers always exceeds the producer biomass.
  • It is a graphical representation of biomass at multiple trophic levels per unit area with fewer producers at the base of the pyramid compared to the tertiary consumer at the highest trophic level of the food chain.
  • The inverted pyramid of biomass is a method for visualizing the composition of an ecosystem. At different trophic levels, they are used to assess the amount of energy converted to living tissue.
  • In the inverted pyramid of biomass, the predatory fish has the largest biomass, and phytoplankton has the lowest biomass.
  • Marine ecosystems, pond ecosystems, etc. are shown inverted pyramids of biomass.
  • An inverted pyramid of biomass is a pyramid indicating the total dry weight of each trophic level in a particular food chain in an ecosystem (5).

Introduction

An ecological pyramid is an important part of an ecosystem. There are three types of ecological pyramids. These are the pyramid of biomass, the pyramid of energy, and the pyramid of numbers. These are an upright pyramid and an inverted pyramid. Below we discussed what the Inverted pyramid of biomass is (1).

Before discussing the inverted pyramid, let’s see what the biomass pyramid is. A biomass pyramid is mainly formed by arranging the biomass of organisms in the ecosystem. This type of ecological pyramid has producers at the bottom and tertiary consumers at the top. So the base of the pyramid of biomass is wide and the top is progressively narrower (1) & (5).

For example in a grassland ecosystem, the biomass of producers (grass) is highest. Then the biomass gradually decreases from the primary consumer (deer) to the secondary consumer (jackal) and from the secondary consumer to the tertiary consumer (tiger).

But some ecosystems do not form a pyramid of biomass like this. The exception is aquatic ecosystems. In this case, the biomass of organisms present in this ecosystem decreases from secondary consumers to producers. As a result, the pyramid appears inverted hence called the inverted pyramid of biomass (3).

Definition

Biomass at a trophic level usually decreases progressively from producers to consumers. But in some cases, this biomass is reduced from consumer to producer. As a result, the pyramid that is formed is inverted in shape. Hence it is called an inverted pyramid of biomass.

Description

  • The dry weight of organisms in a trophic level of an ecosystem or a specific habitat is known as biomass.
  • The pyramid that is formed by arranging these dry weights of organisms at each level of the food chain is called the pyramid of biomass.
  • But in some food chains, these biomass are arranged in reverse. In this case, the pyramid is inverted in shape.
  • It has been found that 15 to 25% of biomass from one trophic level in a food chain is transferred to the next trophic level. Because of this primary consumers have less amount of biomass than producers and secondary consumers have less biomass than primary consumers.
  • But the biomass is reversed in the aquatic ecosystem. In a trophic level of an aquatic ecosystem primary consumers have the highest amount of biomass than producers and secondary consumers have the highest biomass of primary consumers. So in this way, an inverted pyramid of biomass is formed (2) & (4).

Examples

In aquatic ecosystems, the pyramid of biomass is inverted. The biomass of zooplankton (herbivores) is higher than that of phytoplankton (producers), small fish (primary consumers) have higher biomass than zooplankton. And large fishes (secondary consumers) have higher biomass than small fish (1).

Diagram and flow charts

Flow chart

Phytoplankton→ Zooplankton→ Small fish→ large fish

Pyramid of biomass

Q&A

1. What does a pyramid of biomass represent?

A pyramid of biomass represents the total living biomass or organic matter that it present at each trophic level of the food chain in an ecosystem.

2. How does a biomass pyramid work?

It shows the total amount of living biomass available at each trophic level/ the area at the bottom to the producer level. In this way, it works.

3. Why would a biomass pyramid be inverted?

The inverted pyramid of biomass is found in many aquatic ecosystems. So it is inverted because the biomass of fish exceeds that of phytoplankton.

4. Short note on the pyramid of biomass?

A pyramid of biomass is a pyramid formed by adding the biomass of organisms present in a food chain of an ecosystem. There are two types of biomass pyramids, upright and inverted. Forest ecosystem biomass pyramids are upright and aquatic ecosystem biomass pyramids are inverted. It indicates the total mass of each nutrient level in a particular food chain in an ecosystem.

5. Why are biomass pyramids inverted?

The biomass of phytoplankton is lower than that of small herbivorous fish. And the biomass of large carnivorous fish is still high. So the biomass pyramids are inverted.

Written By: Manisha Bharati

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