Zooxanthellae are golden-brown intracellular endosymbionts of various marine animals and protozoa, especially anthozoans. They are typically dinoflagellate algae, although other algae such as diatoms can also be zooxanthellae. They are often acquired by direct ingestion, and subsequently multiply in the host's tissues, providing it with various nutrients. Most are autotrophs and provide the host with energy from photosynthesis. Their population in the host tissue is limited by controlling the amount of food and light they receive and by expulsion of excess cells. There are also zooxanthellae transmitted by the coral eggs. An endosymbiont is any organism that lives within the body or cells of another organism, i. ... Phyla Animals are a major group of organisms, classified as the kingdom Animalia or Meta­zoa. ... Wikisource has an original article from the 1911 Encyclopædia Britannica about: Protozoa Protozoa (in Greek proto = first and zoa = animal) are single-celled eukaryotes (organisms whose cells have nuclei) that show some characteristics usually associated with animals, most notably mobility and heterotrophy. ... Anthozoa is a class within the phylum Cnidaria that contains the sea anemones and corals. ... Classes Dinophyceae Noctiluciphyceae Syndiniophyceae The dinoflagellates are a large group of flagellate protists. ... A seaweed (Laurencia) up close: the branches are multicellular and only about 1 mm thick. ... Diatoms (Gr. ...

Hermatypic (reef-building) corals have zooxanthellae and are largely dependent on them, limiting their growth to the photic zone. The symbiotic relationship is probably responsible for the phenomenal success of corals as reef-building organisms in tropical waters. However, when corals are subjected to high environmental stress, they can lose their zooxanthellae by either expulsion or digestion and die, changing from their normal colour to their white 'skeletons' in a process known as coral bleaching. A reef surrounding an islet. ... Subclasses Alcyonaria Zoantharia See text for orders. ... The photic zone is the depth of the water, whether in a lake or an ocean, that is exposed to sufficient sunlight for photosynthesis to occur. ... Warm pink and yellow tones show where sea surface temperatures in the Great Barrier Reef were warm in the top image. ...

Other organisms which may have zooxanthellae include jellyfish, clams, sea slugs, and radiolaria. There are several different species of zooxanthellae, typically grouped together as the genus Symbiodinium, which appears to be monophyletic. Orders Jellyfish are marine invertebrates belonging to the Scyphozoan class, and in turn the phylum Cnidaria. ... Maxima clam (Tridacna maxima) Clams are shelled marine or freshwater mollusks belonging to the class Bivalvia. ... Sea slug can mean: (in zoology, strict sense): animals of the order Opisthobranchia, or specifically: Nudibranch (often in literature, for example as translation of the Japanese namako): Holothurian This is a disambiguation page: a list of articles associated with the same title. ... Possible classes Polycystinea Acantharea Taxopodea Radiolaria are amoeboid protozoa that produce intricate mineral skeletons, typically with a central capsule dividing the cell into inner and outer portions, called endoplasm and ectoplasm. ... In phylogenetics, a group is monophyletic (Greek: of one stem) if all organisms in that group are known to have developed from a common ancestral form, and all descendants of that form are included in the group. ...