Plankton are numerous organisms that live in large bodies of water and are unable to swim against current. They comprise of algae and bacteria that form the base of aquatic food webs. Plankton are an important source of food for larger animals in the ocean. There are two types of plankton; phytoplankton which are plants and zooplankton which are animals that feed on phytoplankton. Phytoplankton first link in the food chain and are known as primary producers because they produce the first forms of food. Zooplankton and other small marine creatures that graze on the phytoplankton are known as primary consumers and they become food for fish, crustaceans, and other larger species. Phytoplankton account for about half of the photosynthesis on earth and this makes them one of the world’s most important oxygen producers.