Biomass – Population weight

Biomass is the total mass (weight) of an organism multiplied by the number (population size) of that organism in a trophic level.

This is easy to remember if you break the word up:

Biomass means the mass of life

NOTE:

Pyramids of biomass are usually triangular just like a pyramid of energy. However, when looking at marine ecosystems there may be exceptions.

Pyramids of biomass are usually triangular but when studying marine life there are exceptions

Examples

Humans have a global biomass of approximately 350 million tonnes (based on an average mass including children of 50kg and a population size of 7 billion).

Cattle has a global biomass of 520 million tonnes estimated on an average of 400kg multiplied by 1.3 billion population

Cattle have a global biomass of approximately 520 million tonnes (based on an average population mass of 400kg and population size of 1.3 billion).

Chickens have a biomass of 48 million tonnes based on an average mass of 2 kg and 24 billion as an estimate

Chickens have global biomass of 48 million tonnes (based on an average mass of 2kg and a population size of 24 billion).

Blue whales have an estimated 0.5 million tonnes biomass from an average mass of 140,000kg but a population size of roughly 4700

Blue whales have a global biomass of approximately 0.5 million tonnes (based on an average mass of 140,000kg and a population size of roughly 4700 individuals).

Biomass of a krill is an estimated 379 million tones based on an average mass of 0.468g and population of 7.8 x 10(power of 14)

Antarctic krill have a global biomass of approximately 379 million tonnes (based on an average mass of 0.486g and a population size of 7.8 x 10¹⁴).

NOTE:

The above examples are of global biomass, but biomass can also be calculated for a species within a specific area, environment or habitat.