Use this website to discover some of the different types of phytoplankton and zooplankton. You will need this information for the energy pyramid in your stream study project. It is important to understand the difference between phytoplankton and zooplankton in order to properly place them in an energy pyramid. Phytoplankton are autotrophs; they gain their energy directly from the sun and they are plants. Because of how they obtain their energy, they are called producers. Zooplankton must injest other organisms to obtain energy. This makes them consumers. Although they are animal-like, they are protists.