Alveolata is a diverse group of single-celled organisms that are primarily found in aquatic environments. This group includes three main subphyla: Ciliates, Dinoflagellates, and Apicomplexans. Alveolata are characterized by the presence of alveoli, which are small membrane-bound sacs located just beneath their cell membranes. These structures play a role in maintaining cell shape and may be involved in various cellular functions. Members of Alveolata exhibit a wide range of lifestyles, from free-living to parasitic. For example, Ciliates use hair-like structures called cilia for movement and feeding, while Dinoflagellates are known for their bioluminescence and can cause harmful algal blooms. Apicomplexans, such as Plasmodium, are notable for being parasites that cause diseases like malaria.