''Eudistylia'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of marine

polychaete Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called c ...

worms. The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

is ''Eudistylia gigantea'', now accepted as ''Eudistylia vancouveri''. This worm lives in a parchment-like tube with a single opening from which a crown of

tentacle In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

s projects when the worm is submerged. It is a sessile

filter feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a s ...

. the Eudistylia Vancouveri is unique because it has an operculum which makes it possible to fully retract into the tube when predators are sensed.

Characteristics

The head is formed from the

prostomium The prostomium (From Ancient Greek, meaning "before the mouth"; : prostomia; sometimes also called the "acron") is the Cephalization, cephalized first body segment in an annelid worm's body at the anterior end. It is in front of (but does not in ...

and peristomium, which are fused. It bears two bundles of

radiole A radiole is a heavily ciliated feather-like tentacle found in highly organized clusters on the crowns of Canalipalpata. Canalipalpata is an order of sessile marine polychaete worms consisting of 31 families (including the Sabellidae, Serpulida ...

s or feeding tentacles which together form the funnel-shaped multicolored branchial crown divided into two groups on the dorsal and ventral side of the head. Each radiole is pinnately divided and covered in cilia. It has a central stiffening rod of

connective tissue Connective tissue is one of the four primary types of animal tissue, a group of cells that are similar in structure, along with epithelial tissue, muscle tissue, and nervous tissue. It develops mostly from the mesenchyme, derived from the mesod ...

, a number of eyespots and a feeding groove. There are a pair of small palps beside the radioles and a large funnel-shaped mouth. There are about eight thoracic segments and the first has a flange-like collar which secures the worm to the mouth of its tube. The thoracic segments bear two rows of

setae In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae ...

or bristles, the notochaetae on the dorsal side are grouped in tufts, while the neurochaetae on the ventral side form a row of small hooks. The abdomen is long and has many segments. The position of the setae on the abdominal segments is reversed, with the notochaetae being hooked and the neurochaetae being tufted. The pygidium at the posterior tip bears the large anus. There is a furrow on the dorsal side of the thoracic and abdominal segments called the faecal groove through which faecal material and gametes are transported to the open end of the tube.

Distribution

Members of this genus are found on the Pacific coasts of Canada, the United States and Mexico. A group of feather duster worms is called a hummock. When these hummocks are created kelp attaches itsef to them by the

holdfast Holdfast most often refers to: *Holdfast (biology), a root-like structure that anchors aquatic sessile organisms to their substrate *Holdfast (tool), a tool used to secure a workpiece to a workbench or anvil Holdfast or hold fast may also refer t ...

, finding a habitat where kelp would not normally establish itself.

Species

*'' Eudistylia brevicomata'' (Ehlers, 1905) *'' Eudistylia catharinae'' Banse, 1979 *'' Eudistylia ceratodaula'' (Schmarda, 1861) *''

Eudistylia polymorpha ''Eudistylia polymorpha'', the giant feather duster worm, is a species of marine polychaete worm belonging to the family Sabellidae. Its common name is from the crown of tentacles extended when the animal is under water. Description ''E. polymor ...

'' (Johnson, 1901) *'' Eudistylia tenella'' Bush, 1904 *''

Eudistylia vancouveri ''Eudistylia'' is a genus of marine polychaete worms. The type species is ''Eudistylia gigantea'', now accepted as ''Eudistylia vancouveri''. This worm lives in a parchment-like tube with a single opening from which a crown of tentacles projects ...

'' (Kinberg, 1866) World Register of Marine Species
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References

{{Taxonbar, from=Q3605424 Sabellida Annelid genera