Food pyramids show relationships between the above trophic levels. A pyramid of numbers would show the actual total number of organisms at each trophic level for a given area. The greatest number of organisms would be at the primary producer level, decreasing greatly as you move up the pyramid. A pyramid of energy would show the energy available at each trophic level for a given area. As you move up the pyramid the amount of energy available is drastically reduced.
Much energy is lost as heat and through respiration.
Primary producers would, by far, have the greatest biomass. As you move up the pyramid each trophic level has much less biomass than the level below it. Ecosystems can be very complicated, and while food pyramids are not perfect, they do give a nice pictorial representation of trophic relationships. Reproduction in whole or in part without permission is prohibited.