Difference Between Pyramid of Biomass and Pyramid of Energy

The key difference between pyramid of biomass and pyramid of energy is that a pyramid of biomass shows how much biomass is present in the organisms of each trophic level while a pyramid of energy shows how much energy is retained in the form of new biomass at each trophic level.

Ecological pyramids are pyramid-shaped diagrams of energy flow, biomass accumulation, and the number of individuals at different trophic levels in an ecosystem. There are three types of ecological pyramids as pyramid of numbers, pyramid of biomass and pyramid of energy. Pyramid of numbers represents the number of individual organisms at each trophic level. Pyramid of biomass represents the biomass present at each trophic level while pyramid of energy shows the energy available at each trophic level. All three types of pyramids are useful for characterizing ecosystem structure.

CONTENTS

1. Overview and Key Difference
2. What is a Pyramid of Biomass
3. What is a Pyramid of Energy
4. Similarities Between Pyramid of Biomass and Pyramid of Energy
5. Side by Side Comparison – Pyramid of Biomass vs Pyramid of Energy in Tabular Form
6. Summary

What is a Pyramid of Biomass?

Pyramid of biomass is an ecological pyramid that represents the biomass of different trophic levels within an ecosystem. Biomass is the total amount of dry mass of organisms in a given area. It compares the biomass at each level. Similar to a pyramid of energy, primary producers occupy the highest biomass. In general, only 10 -20 % biomass is transferred from one trophic level to the trophic level above.

Generally, biomass pyramids are upright since there is a decrease in biomass with the increase in the trophic level. However, there are inverted biomass pyramids as well. Inverted biomass pyramids can be seen in marine ecosystems.

What is a Pyramid of Energy?

Pyramid of energy is one of the three types of ecological pyramids. Energy pyramid shows how much energy is available at each trophic level of a food chain. Therefore, energy pyramid compares the energy in producers, primary consumers, secondary consumers, tertiary consumers in a food chain. Generally, a big portion of the energy is lost when going from one trophic level to next. About 90% of energy is lost as heat. Therefore, each level above gets smaller. The highest energy is available in primary producers, so energy pyramids have a large base or producers.

Primary producers absorb energy from sunlight to produce their own food. Herbivores eat plants and get energy. They get only 10%, and the rest of the 90% is lost as heat. Carnivores eat herbivores and get energy. However, they also get only 10 % of the energy of herbivores. Remaining 90 % is lost as heat into the environment. Likewise, energy is lost at each level. Therefore, the energy transfer between trophic levels is generally insufficient.

What are the Similarities Between Pyramid of Biomass and Pyramid of Energy?

• Pyramid of biomass and pyramid of energy are two of the three types of ecological pyramids.
• Both represent trophic levels in an ecosystem.
• They are important in understanding the relationships between organisms and trophic levels in an ecosystem.
• Most pyramids show only four trophic levels since most ecosystems only have four trophic levels.
• Most pyramids of biomass and all pyramids of energy are upright.

What is the Difference Between Pyramid of Biomass and Pyramid of Energy?

Pyramid of biomass represents how mush biomass is present in each trophic level while pyramid of energy represents the energy flow through trophic levels in an ecosystem. So, this is the key difference between pyramid of biomass and pyramid of energy. The pyramid of biomass can be upright or inverted, but pyramid of energy is always upright. Moreover, biomass in a biomass pyramid is measured in units of kilograms per square meter (kgm^-2) while energy in an energy pyramid is measured in units of kilocalories (kcal).

Below infographic tabulates the differences between pyramid of biomass and pyramid of energy.

Summary – Pyramid of Biomass vs Pyramid of Energy

Pyramid of biomass shows the amount of biomass at each trophic level in an ecosystem while pyramid of energy shows the flow of energy from one trophic level to the next in an ecosystem. This is the key difference between pyramid of biomass and pyramid of energy. Generally, only 10 – 20 % biomass is transferred from one level to the next level while only 10% of energy is transferred from one level to the next level. Energy pyramids are always upright. Generally, biomass pyramids are upright. But there are inverted biomass pyramids as well. Thus, this summarizes the difference between pyramid of biomass and pyramid of energy.

Reference:

1. “Energy Flow and Primary Productivity (Article).” Khan Academy, Available here.
2. “3 Major Types of Ecological Pyramids: Pyramid of Number, Biomass and Energy.” Your Article Library, 18 Dec. 2013, Available here.

Image Courtesy:

1. “Numbers Pyramid” By Swiggity.Swag.YOLO.Bro – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Ecological Pyramid” By Swiggity.Swag.YOLO.Bro – Extracted from this Commons file (CC BY-SA 4.0) via Commons Wikimedia