Dinophytes acquired chloroplasts obviously early in evolution and later lost them multiple times. Most families and genera contain both photosynthetic and heterotrophic species. Chloroplasts enveloped by three membranes with thylakoids in stacks of three, containing peridinin as the main pigment, are regarded as the original dinophyte plastids. Pyrenoids are generally present. Stigmata, if present, are usually parts of the chloroplast or are modified original plastids. The form II type RUBISCO found in the dinophytes is unique for eukaryotes, otherwise known only in some anaerobic bacteria. It is disputed whether the original dinophyte chloroplasts are derived from a prokaryotic or an eukaryotic endosymbiosis. Various dinoflagellates contain aberrant chloroplasts.Glenodinium foliaceumandPeridinium balticumhave a single complete endosymbiont, originally a pcnnate diatom.Podolampas bipeshouses several dictyophycean symbiont cells. The “symbionts” ofLepidodiniurn virideandGymnodinium chlorophorumare highly reduced prasinophyte cells. The chloroplasts ofGymnodinium mikimotoihave aberrant pigments (fucoxanthin derivatives, no peridinin) and fine structure. The dinoflagellate hosts do not seem to contain any parts of the former endosymbiont except the chloroplasts. PhotosyntheticDinophysisspecies have cryptophycean-like chloroplasts, whereas symbiotic cyanobacteria are found in other members of the Dinophysiales, e.g.,Ornithocercus.Various dinophytes, e.g.Gymnodinium aeruginosum, use kleptochloroplasts from ingested cryptophytes transiently for photosynthesis. Original or secondarily acquired chloroplasts can only be used for phylogenetic considerations in exceptionally cases: it seems unlikely that the Prorocentrales have evolved from the Dinophysiales because all Prorocentrales possess original dinoflagellate chloroplasts, whereas no member of the Dinophysiales has such chloroplasts.