Marine phytoplankton which constitutes diatoms, dinoflagellates, blue-green algae, silicoflagellates, cocolithophors etc. contributes about 95% of primary production in the oceans. On this depends the secondary production (zooplankton) and tertiary production (fish, shellfish, mammals, etc.). Since phytoplankton serve as a basic food source for animals in the sea their presence in large numbers may indicate the abundance of commercially important fish and shellfish populations. Coastal waters around India contain diverse groups of phytoplankton. The biodiversity of these organisms is threatened due to large scale release of domestic and industrial wastes. Hence there is a need to study these organisms in more details. The organization of this manual is made with a broad outline to accommodate the specific need of our Indian coastal waters. The manual is divided in chapters which include - method of collection, preservation and identification procedures. Species chosen for description were selected to provide good representation of the commonly important species to give full spectrum of Chaetoceros to be found in phytoplankton. The details should help the students as well as researches to be thorough in the method of collection and identification of the different phytoplanktonic species.