A. 5. The pyramid of biomass is a pictorial representation of the total biomass of each part of the ecosystem, stacked in the form of a pyramid. It starts with the producers forming the lowest rung, with the successive consumers forming the upper rungs of the pyramid. The biomass of each part determines the size of the rung. For this reason, a terrestrial ecosystem forms an upright pyramid, with the producers contributing the most to the total biomass of the ecosystem, while the apex predators are contributing the least. An inverted pyramid is observed in the ocean ecosystem, since the producers, the phytoplanktons contribute less to the biomass than the zooplankton, the primary consumers.