Many types of plankton are microscopic, but jellyfish that are meters long can be considered plankton because they always travel with the current. These organisms can be divided into two main categories: Phytoplankton and Zooplankton.Animal-like plankton are called zooplankton. These organisms need to consume other organisms, like phytoplankton, to survive. While phytoplankton are the base of the food web, zooplankton are the next level.These animals take energy from phytoplankton and then they themselves become food for larger marine life.he question is actually harder than students think, because plankton can be small, they can be big, they can be plants, and they can be animals. Plankton are not just one thing, they are a lifestyle, a way an organism lives in its environment. Plankton are drifters, meaning they cannot move against a current.