plants, agricultural and forest residues and all forms of human, animal and plant waste. Any type of plant or animal material that can be converted into energy is called biomass. When these materials are used for energy production. They are known as biofuels. The pyramid of biomass represents the relationships that exist between the quantity of living matter (biomass) at different trophic levels. In terrestrial ecosystems, the biomass progressively decreases from producers to top carnivores.

Are the pyramids always upright?

In an aquatic ecosystem, the biomass of phytoplankton is quite negligible as compared to that of the crustaceans and small herbivorous fish that feed on these producers. The biomass of large carnivorous fish living on small fishes is still greater. This makes the pyramid of biomass inverted. It is found that 10 - 20 % of the biomass is transferred from one tropic level to the next in a food chain. A more accurate idea of food relationship may be obtained if the above pyramid of numbers is converted into a pyramid of biomass. This indicates the mass of plant matter which is used by the aphids to produce the mass of the of aphids population, the total mass of the ladybird population that could be supported by the aphids and so on through out the chain. In short we can say that biomass is food for the next trophic level in a food chain

The biomass in a trophic level may be more or less than the other trophic levels. Biomass is a measure of the amount of food available. When animals eat, only a small proportion of their food is converted into new tissue, which inturn forms the food for the next trophic level. Most of the biomass that animals eat is either not digested, or used to provide the energy needed for staying alive.

The biomass pyramid shows that animals are relatively inefficient in converting food into body tissues, the remaining part of the food being undigested is passed out as waste, or broken down in respiration to supply