There are two apparent trends represented in an energy pyramid. First, there are enormous numbers and masses of individual animals or plants at the bottom and the numbers decrease as you reach the top. Secondly, the sizes and energy needs of the individual organisms generally increase as you reach higher levels.
The bottom, or base, of an energy pyramid is a position always held by the producers and represents (by far) the largest percentage of biomass for the food web. The need for such a large biomass of producers is to support the energy needs for all the organisms at higher trophic levels.
In the illustration above, the osprey is positioned at the highest trophic level. Therefore, for the energy transformations represented by the pyramid, the osprey is the organism with the greatest energy needs and relies on all of the transactions from producers to consumers to have enough energy left over to fill its own energy needs.
It should be acknowledged that ecosystems are very complex and any food chain, food web or energy pyramid simply illustrates the general idea. It would be practically impossible to illustrate all the possible ways that animals interact and all the possible ways that energy moves throughout an ecosystem.