Sea Squirt Coral 382

Ascidiacea, commonly known as the ascidians, tunicates (in part), and sea squirts (in part), is a polyphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders.^[2] Ascidians are characterized by a tough outer “tunic” made of a polysaccharide, the cellulose. Ascidians are found all over the world, usually in shallow water with salinities over 2.5%. While members of the Thaliacea and Larvacea (Appendicularia) swim freely like plankton, sea squirts are sessile animals after their larval phase: they then remain firmly attached to their substratum, such as rocks and shells. There are 2,300 species of ascidians and three main types: solitary ascidians, social ascidians that form clumped communities by attaching at their bases, and compound ascidians that consist of many small individuals (each individual is called a zooid) forming colonies up to several meters in diameter. Sea squirt coral 382 feed by taking in water through a tube, the oral siphon. The water enters the mouth and pharynx, flows through mucus-covered gill slits (also called pharyngeal stigmata) into a water chamber called the atrium, then exits through the atrial siphon.  Sea squirt  coral 382 are rounded or cylindrical animals ranging from about 0.5 to 10 cm (0.2 to 4 in) in size. One end of the body is always firmly fixed to rock, coral, or some similar solid surface. The lower surface is pitted or ridged, and in some species has root-like extensions that help the animal grip onto the surface. The body wall is covered by a smooth thick tunic, which is often quite rigid. The tunic consists of cellulose along with proteins and calcium salts. Unlike the shells of molluscs, the tunic is composed of living tissue, and often has its own blood supply. In some colonial species, the tunics of adjacent individuals are fused into a single structure.  Almost all ascidians are hermaphrodites and conspicuous mature ascidians are sessile.