The document discusses the three basic types of ecological pyramids used by ecologists - pyramids of number, pyramids of biomass, and pyramids of energy. Pyramids of number show the population size at each trophic level. Pyramids of biomass represent the total mass or biomass at each level, which decreases by 90% each level. Pyramids of energy depict the energy content in kilocalories per unit area per year, which decreases by 10% at each trophic level as energy is lost to the environment.