Zooxanthellae are golden-brown intracellular endosymbionts of various marine animals and protozoa, especially anthozoans such as the scleractinian corals and the tropical sea anemone Aiptasia sp. They are typically dinoflagellate algae, although heterokont algae such as diatoms can also be zooxanthellae. They may be acquired by direct ingestion, and subsequently reproduce by splitting apart; a process known as budding. In other cases, zooxanthellae may be transmitted by the coral eggs and planu… (More on Zooxanthella)