Kingdom Protista

Kingdom Protista is a kingdom of Domain Eukarya. Kingdom Protista consists of 6 phyla: Ciliophora, Zoomastigina, Euglenophyta, Chlorophyta, Phaeophyta, and Rhodophyta. The organisms of this kingdom can be unicellular, colonial, or multicellular. Organisms of Kingdom Protista can be either heterotrophic or autotrophic. Examples of heterotrophic protists are found in phylum Ciliophora. An example of autotrophic protists is Nereocystis luetkeana or Bull Kelp, which produces energy via photosynthesis. Digestion is intracellular. Reproduction can be both Asexual and Sexual. Protozoans can have meiotic cell divisions and mitotic. An example of a multicellular organism of Kingdom Protista is Macrocystis pyrifera or better known as Giant Kelp. An example of a unicellular organism of Kingdom Protista is Arachnoidiscus ehrenbergi, which is a diatom. The gas exchange of these organisms is done by simple diffusion across the cell walls. 

This is a diagram and a microscopic view (labeled) of Dinoflagellates.