A healthy natural system is expected to possess five “consumer” categories. For example, in the ocean the first stage of the food pyramid is the phytoplankton, a microscopic algae, which is eaten by zooplankton, tiny microscopic animals either in their larval, juvenile or adult stages, which are then consumed by shellfish, corals, mollusks, and small filtering fish. Above them are carnivores, basically predators and cetaceans.