xanth-, xantho-, xan-

(Greek: the color yellow; blond)

zooxanthella (s), zooxanthellae (pl)
1. A microscopic yellow-green alga that lives symbiotically within the cells of some marine invertebrates, especially corals.
2. Plantlike flagellate protozoans in the order Dinoflagellida, photosynthesizing symbiotes inside the cells of sponges, corals, and others.
3. Unicellular yellow algae containing xanthophyll and living as symbionts in the tissues of higher organisms; such as, sponges, coelenterates, worms, etc.
A monofamilial order of mostly intrafamilial symbiont flagellates of the class Dionphyceae, noted for excreting large amounts of photosynthate as glycerol and aiding in the calcification of corals.