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Zooxanthellae
Dinoflagellates in symbiosis with coral, jellyfish and nudibranchs / From Wikipedia, the free encyclopedia
Zooxanthellae (/ˌzoʊəzænˈθɛliː/; sg. zooxanthella) is a colloquial term for single-celled dinoflagellates that are able to live in symbiosis with diverse marine invertebrates including demosponges, corals, jellyfish, and nudibranchs. Most known zooxanthellae are in the genus Symbiodinium,[1] but some are known from the genus Amphidinium, and other taxa, as yet unidentified, may have similar endosymbiont affinities.[2] The true Zooxanthella K.brandt is a mutualist of the radiolarian Collozoum inerme (Joh.Müll., 1856)[3] and systematically placed in Peridiniales.[4][lower-alpha 1] Another group of unicellular eukaryotes that partake in similar endosymbiotic relationships in both marine and freshwater habitats are green algae zoochlorellae.[6]
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Zooxanthellae are photosynthetic organisms, which contain chlorophyll a and chlorophyll c, as well as the dinoflagellate pigments peridinin and diadinoxanthin. These provide the yellowish and brownish colours typical of many of the host species.[2] During the day, they provide their host with the organic carbon products of photosynthesis, sometimes providing up to 90% of their host's energy needs for metabolism, growth and reproduction. In return, they receive nutrients, carbon dioxide, and an elevated position with access to sunshine.[7][8]