include the oligochaetes (earthworms and leeches), sipunculans, and echiurans. the pogonophora and vestimentifera were once considered separate phyla, but are now classified in the polychaete family siboglinidae. much of the classification below matches rouse & fauchald, 1998, although that paper does not apply ranks above family. older classifications recognize many more (sub)orders than the layout presented here. as comparatively few polychaete taxa have been subject to cladistic analysis, some groups which are usually considered invalid today may eventually be reinstated. these divisions were shown to be mostly paraphyletic in recent years. basal or incertae sedis family diurodrilidae family histriobdellidae family nerillidae family parergodrilidae family potamodrilidae family psammodrilidae family spintheridae family protodriloididae family saccocirridae order haplodrili order myzostomida family endomyzostomatidae family asteromyzostomatidae family myzostomidae subclass palpata family protodrilidae family polygordiidae subclass aciculata family levidoridae order amphinomida family amphinomidae family euphrosinidae order eunicida family dorvilleidae family eunicidae family hartmaniellidae family ichthyotomidae family lumbrineridae family oenonidae family onuphidae order phyllodocida suborder aphroditiformia family acoetidae family aphroditidae family eulepethidae family iphionidae family pholoidae family polynoidae family sigalionidae suborder glyceriformia family glyceridae family goniadidae family lacydoniidae family paralacydoniidae suborder nereidiformia family antonbruunidae family chrysopetalidae family hesionidae family nereididae family pilargidae family syllidae suborder phyllodocida incertae sedis family iospilidae family nautiliniellidae family nephtyidae family typhloscolecidae family tomopteridae suborder phyllodociformia family alciopidae family lopadorrhynchidae family phyllodocidae family pontodoridae subclass sedentaria family chaetopteridae infraclass canalipalpata order sabellida family caobangidae family fabriciidae family oweniidae family sabellariidae family sabellidae family serpulidae family siboglinidae (formerly the phyla pogonophora & vestimentifera) order spionida suborder spioniformia family apistobranchidae family longosomatidae family magelonidae family poecilochaetidae family spionidae family trochochaetidae family uncispionidae order terebellida suborder cirratuliformia family acrocirridae (sometimes placed in spionida) family cirratulidae (sometimes placed in spionida) family ctenodrilidae (sometimes own suborder ctenodrilida) family fauveliopsidae (sometimes own suborder fauveliopsida) family flabelligeridae (sometimes suborder flabelligerida) family flotidae (sometimes included in flabelligeridae) family poeobiidae (sometimes own suborder poeobiida or included in flabelligerida) family sternaspidae (sometimes own suborder sternaspida) suborder terebellomorpha family alvinellidae family ampharetidae family pectinariidae family terebellidae family trichobranchidae infraclass scolecida family arenicolidae family capitellidae family cossuridae family maldanidae family opheliidae family orbiniidae family paraonidae family scalibregmatidae order capitellida (nomen dubium) order cossurida (nomen dubium) order opheliida (nomen dubium) order orbiniida (nomen dubium) order questida (nomen dubium) order scolecidaformia (nomen dubium) subclass echiura order bonelliida family bonelliidae family ikedidae order echiurida family echiuridae family thalassematidae family urechidae