Editing Tunicate (section)

==Feeding==
[[File:Tunicate black orange.jpg|thumb|left|''[[Clavelina robusta]]'' (black and white) and ''[[Pycnoclavella flava]]'' (orange) showing siphons.]]

Nearly all adult tunicates are [[suspension feeder]]s (the larval form usually does not feed), capturing [[plankton]]ic particles by filtering sea water through their bodies. Ascidians are typical in their digestive processes, but other tunicates have similar systems. Water is drawn into the body through the buccal siphon by the action of [[Cilium|cilia]] lining the gill slits. To obtain enough food, an average ascidian needs to process one body-volume of water per second.<ref name=Ruppert/> This is drawn through a net lining the pharynx which is being continuously secreted by the endostyle. The net is made of sticky mucus threads with holes about 0.5&nbsp;μm in diameter which can trap planktonic particles including [[bacteria]]. The net is rolled up on the dorsal side of the pharynx, and it and the trapped particles are drawn into the [[esophagus]]. The gut is U-shaped and also ciliated to move the contents along. The stomach is an enlarged region at the lowest part of the U-bend. Here, digestive [[enzyme]]s are secreted and a [[Pylorus|pyloric]] gland (absent in appendicularians)<ref>[https://books.google.com/books?id=qSJsKEhV3FsC&dq=Appendicularia+pyloric+gland&pg=PA164 Response of Marine Ecosystems to Global Change: Ecological Impact of Appendicularians]</ref> adds further secretions. After digestion, the food is moved on through the [[intestine]], where absorption takes place, and the [[rectum]], where undigested remains are formed into [[Feces|faecal]] pellets or strings. The [[anus]] opens into the dorsal or [[cloaca]]l part of the peribranchial cavity near the atrial siphon. Here, the faeces are caught up by the constant stream of water which carries the waste to the exterior. The animal orientates itself to the current in such a way that the buccal siphon is always upstream and does not draw in contaminated water.<ref name=Ruppert/>

Some ascidians that live on soft sediments are [[detritivore]]s. A few deepwater species, such as ''[[Megalodicopia hians]]'', are [[Ambush predator|sit-and-wait predators]], trapping tiny crustacea, nematodes, and other small invertebrates with the muscular lobes which surround their buccal siphons. Certain tropical species in the family [[Didemnidae]] have [[Symbiosis|symbiotic]] green algae or [[cyanobacteria]] in their tunics, and one of these symbionts, ''[[Prochloron]]'', is unique to tunicates. Excess [[Photosynthesis|photosynthetic]] products are assumed to be available to the [[Host (biology)|host]].<ref name=Ruppert/>