A. The answer to your question is "yes," with qualifications. Let me explain. The general pyramid scheme you refer to holds true as long as you are making broad classifications of the organisms in the pyramid. For instance, if you use the classifications of plants, herbivores, carnivores, the pyramid exists whether you base it on numbers, weights, or even calories of energy. Where the pyramid generalization starts to break down is when you start breaking up these classifications into their constituents, e.g., the different kinds of plants (algae, vascular plants), or even further into the different species. Or breaking down the herbivores into all the different insects and other macroinvertebrates that feed on plants in different ways. Then, when you start listing these, and drawing arrows connecting who feeds on what, you come up with a food-web, rather than a simple pyramid. Both can be accurate; one just tells you more about how the individual parts of the ecosystem fit together.