In pond ecosystem producers are the smallest organisms while, carnivores are large in size. Consequently, there is a gradual increase in biomass of organisms at successive trophic levels from producers onward to top carmivores resulting in inverted pyramid. Thus, the biomass of phytoplanktons will be smaller than that of zooplanktons. The biomass of zooplanktons will be lesser than of primary carnivores ($e.g,$ small fishes). In such a inverted pyramid of biomass, small standing crop of phytoplankton support a large standing crop of zooplankton