Final answer:
Ecological pyramids visualize the amount of energy, biomass, and number of organisms across trophic levels. While energy pyramids are always upright due to energy loss, number and biomass pyramids can be inverted depending on organism size and production rates, as exemplified by summer grasslands and phytoplankton in the English Channel.
Step-by-step explanation:
Ecological pyramids, also known as Eltonian pyramids, are graphical representations that depict the relative amounts of energy, biomass, and number of organisms at each trophic level in an ecosystem. Ecological pyramids highlight the energy flow as well as the structure of the ecosystem. There are three types of ecological pyramids: pyramids of energy, number, and biomass.
Energy pyramids are always upright, because energy decreases as it travels from the base (producers) to the top (apex predators), according to the second law of thermodynamics. In contrast, pyramids of number and biomass can be inverted or even diamond-shaped due to variable organism size and productivity. For instance, in an ecosystem where few large trees support many small herbivores, the biomass pyramid may appear inverted.
Examples of inverted pyramids include a number pyramid in grasslands during summer, where there may be fewer producers than herbivores, and the biomass pyramid in the English Channel, where the mass of phytoplankton (primary producers) is less than that of the zooplankton (primary consumers) due to the high turnover rate of phytoplankton, despite quick reproduction.