Ecological pyramids show the mass or amount of energy stored by organisms at each trophic level.
Pyramids of Number
These show the numbers of organisms at each trophic level.
The number of organisms at lower trophic levels is greater than the number of organisms at higher trophic levels.
- No account is taken of size
- The number of individuals is so great that it is impossible to represent them accurately on the same scale as other species
Pyramids of Biomass
Biomass is the total mass of the plants and/or animals in a particular place. This method is more reliable and quantitative.
Biomass is measured in grams per meter squared.
- The presences of varying amount of water makes it unreliable
- Animals have to be killed
Pyramids of Energy
The most accurate representation of energy flow.
Measures the energy stored in organisms.
More reliable than biomass because two organisms of the same dry mass may store different amounts of energy.
Measure in kilojoules per meter squared per year.
- Collecting data can be difficult and complex