Zooxanthellae

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Zooxanthellae (; zooxanthella) is a colloquial term for photosynthetic single-celled organisms capable of symbiosis with diverse marine invertebrates such as corals, jellyfish, demosponges, and nudibranchs. Most known zooxanthellae are in the dinoflagellate genus Symbiodinium, but some are known from the genus Amphidinium, and other taxa, as yet unidentified, may have similar endosymbiont affinities. The genus name "Zooxanthella"(meaning literally "little yellow animal") was originally given by Karl Brandt in 1881 to Zooxanthella nutricula (a mutualist of the radiolarian Collozoum inerme) which has been placed in the Peridiniales. Another group of unicellular eukaryotes that partake in similar endosymbiotic relationships in both marine and freshwater habitats are green algae zoochlorellae.