Editing Echiura (section)

==Behaviour==
A spoon worm can move about on the surface by extending its proboscis and grasping some object before pulling its body forward. Some worms, such as ''[[Echiurus]]'', can leave the [[Substrate (biology)|substrate]] entirely, swimming by use of the proboscis and contractions of the body wall.<ref>{{Cite EB1911|wstitle= Echiuroidea |volume= 08 |last= Shipley |first= Arthur Everett |author-link= Arthur Everett Shipley | pages = 882&ndash;883 }}</ref>

Digging behaviour has been studied in ''[[Echiurus echiurus]]''. When burrowing, the proboscis is raised and folded backwards and plays no part in the digging process. The front of the trunk is shaped into a wedge and pushed forward, with the two anterior chaetae (hooked chitinous bristles) being driven into the sediment. Next the rear end of the trunk is drawn forward and the posterior chaetae anchor it in place. These manoeuvres are repeated and the worm slowly digs its way forwards and downwards. It takes about forty minutes for the worm to disappear from view. The burrow descends diagonally and then flattens out, and it may be a metre or so long before ascending vertically to the surface.<ref>{{cite web |url=https://inverts.wallawalla.edu/Echiura/Echiurus_echiurus.html |title=''Echiurus echiurus'' subspecies ''alaskanus'' Fisher, 1946 |author=Cowles, Dave |year=2005 |work=Invertebrates of the Salish Sea |access-date=18 February 2019}}</ref>

[[Image:Echiurien Thiladhoo.JPG|thumb|right|Characteristic forked proboscis of an echiurian worm in the Maldives]]
[[File:Bonélie (Bonellia viridis) PC301461.JPG|thumb|''[[Bonellia viridis]]'', female]]
Spoon worms are typically [[detritivore]]s, extending the flexible and mobile proboscis and gathering organic particles that are within reach. Some species can expand the proboscis by ten times its contracted length. The proboscis is moved by the action of cilia on the lower (ventral) surface "creeping" it forward. When food particles are encountered, the sides of the proboscis curl inward to form a ciliated channel.<ref name=Ruppert/>

A worm such as ''Echiurus'', living in the sediment, extends its proboscis from the rim of its burrow with the ventral side on the substrate. The surface of the proboscis is well equipped with [[mucus|mucous]] glands to which food particles adhere. The mucus is bundled into boluses by [[Cilium|cilia]] and these are passed along the feeding groove by cilia to the mouth. The proboscis is periodically withdrawn into the burrow and later extended in another direction.<ref name=Walls/>

''[[Urechidae]]'', another group of tube-dwellers, has become [[filter feeder]]s.<ref>[https://kmkjournals.com/upload/PDF/ArthropodaSelecta/27/27_4_319_324_Burukovsky_Marin_for_Inet.pdf The food composition of the symbiotic crab Pinnixa rathbunae Sakai, 1934 (Brachyura: Pinnotheridae) from burrows of the spoon worm Urechis unicinctus (von Drasche, 1881 (Echiurida: Urechidae) in Vostok Bay of the Sea of Japan]</ref> It has a short proboscis and a ring of mucous glands at the front of its body. It expands its muscular body wall to deposit a ring of mucus on the burrow wall then retreats backwards, exuding mucus as it goes and spinning a mucus net. It then draws water through the burrow by [[Peristalsis|peristaltic contractions]] and food particles stick to the net. When this is sufficiently clogged up, the spoon worm moves forward along its burrow devouring the net and the trapped particles. This process is then repeated and in a nutrient-rich area may take only a few minutes to complete. Large particles are squeezed out of the net and eaten by other [[invertebrate]]s living [[Commensalism|commensally]] in the burrow. These typically include a small [[crab]], a [[Polynoidae|scale worm]] and often a [[fish]] lurking just inside the back entrance.<ref name=Walls/>

''[[Ochetostoma erythrogrammon]]'' obtains its food by another method. it has two vertical burrows connected by a horizontal one. Stretching out its proboscis across the substrate it shovels material into its mouth before separating the edible particles. It can lengthen the proboscis dramatically while exploring new areas and periodically reverses its orientation in the burrow so as to use the back entrance to feed.<ref>{{cite journal |author=Chuang, S. H. |year=1962 |title=Feeding Mechanism of the Echiuroid, ''Ochetostoma erythrogrammon'' Leuckart & Rueppell, 1828 |journal=Biological Bulletin |volume=123 |issue=1 |pages=80&ndash;85 |doi=10.2307/1539504 |jstor=1539504 |url=https://www.biodiversitylibrary.org/part/37785 }}</ref> Other spoon worms live concealed in rock crevices, empty gastropod shells, sand dollar [[Test (biology)|tests]] and similar places, extending their proboscises into the open water to feed.<ref name=II/> Some are [[scavenger]]s or detritivores, while others are interface grazers and some are [[Filter feeder|suspension feeders]].<ref>{{cite WoRMS |author=van der Land, Jacob |year=2004 |title=Echiuroidea |id=110342 |access-date=30 November 2011}}</ref>

While the proboscis of a burrowing spoon worm is on the surface it is at risk of [[predation]] by bottom-feeding fish. In some species, the proboscis will [[Autotomy|autotomise]] (break off) if attacked and the worm will regenerate a proboscis over the course of a few weeks.<ref name=Walls/> In a study in California, one of the most commonly found dietary items of the [[leopard shark]] was found to be the tube-dwelling [[Urechis caupo|innkeeper worm]] (''Urechis caupo'') which it extracted from the sediment by suction.<ref>{{cite journal |author=Tallent, L.G. |year=1976 |title=Food habits of the leopard shark, Triakis semifasciata, in Elkhorn Slough, Monterey Bay, California |journal=California Fish and Game |volume=62 |issue=4 |pages=286–298 |url=https://www.cabdirect.org/cabdirect/abstract/19771453560 }}</ref>