Polychaeta () is a

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

class of generally marine

annelid The annelids (Annelida , from Latin ', "little ring"), also known as the segmented worms, are a large phylum, with over 22,000 extant species including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecol ...

worm Worms are many different distantly related bilateral animals that typically have a long cylindrical tube-like body, no limbs, and no eyes (though not always). Worms vary in size from microscopic to over in length for marine polychaete worm ...

s, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of

chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...

. More than 10,000 species are described in this class. Common representatives include the lugworm (''Arenicola marina'') and the sandworm or

clam worm Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two shel ...

''Alitta''. Polychaetes as a class are robust and widespread, with species that live in the coldest ocean temperatures of the abyssal plain, to forms which tolerate the extremely high temperatures near hydrothermal vents. Polychaetes occur throughout the Earth's oceans at all depths, from forms that live as

plankton Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a cr ...

near the surface, to a 2- to 3-cm specimen (still unclassified) observed by the robot ocean probe ''Nereus'' at the bottom of the Challenger Deep, the deepest known spot in the Earth's oceans. Only 168 species (less than 2% of all polychaetes) are known from fresh waters.

Description

Polychaetes are segmented worms, generally less than in length, although ranging at the extremes from to , in '' Eunice aphroditois''. They can sometimes be brightly coloured, and may be

iridescent Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to gradually change color as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, feathers, butterfl ...

or even luminescent. Each segment bears a pair of paddle-like and highly vascularized parapodia, which are used for movement and, in many species, act as the worm's primary respiratory surfaces. Bundles of bristles, called chaetae, project from the parapodia. However, polychaetes vary widely from this generalised pattern, and can display a range of different body forms. The most generalised polychaetes are those that crawl along the bottom, but others have adapted to many different

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (fo ...

s, including burrowing, swimming, pelagic life, tube-dwelling or boring,

commensal Commensalism is a long-term biological interaction ( symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fr ...

ism, and parasitism, requiring various modifications to their body structures. The head, or prostomium, is relatively well developed, compared with other annelids. It projects forward over the mouth, which therefore lies on the animal's underside. The head normally includes two to four pair of eyes, although some species are blind. These are typically fairly simple structures, capable of distinguishing only light and dark, although some species have large eyes with lenses that may be capable of more sophisticated vision, including the Alciopids' complex eyes which rival cephalopod and vertebrate eyes. The head also includes a pair of antennae, tentacle-like palps, and a pair of pits lined with

cilia The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projecti ...

, known as "nuchal organs". These latter appear to be chemoreceptors, and help the worm to seek out food.

Internal anatomy and physiology

The outer surface of the body wall consists of a simple

columnar epithelium Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellular ...

covered by a thin cuticle. Underneath this, in order, are a thin layer of connective tissue, a layer of circular muscle, a layer of longitudinal muscle, and a

peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesot ...

surrounding the body cavity. Additional oblique muscles move the parapodia. In most species the body cavity is divided into separate compartments by sheets of peritoneum between each segment, but in some species it's more continuous. The mouth of polychaetes is located on the peristomium, the segment behind the prostomium, and varies in form depending on their diets, since the group includes predators, herbivores, filter feeders, scavengers, and parasites. In general, however, they possess a pair of jaws and a

pharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its ...

that can be rapidly everted, allowing the worms to grab food and pull it into their mouths. In some species, the pharynx is modified into a lengthy

proboscis A proboscis () is an elongated appendage from the head of an animal, either a vertebrate or an invertebrate. In invertebrates, the term usually refers to tubular mouthparts used for feeding and sucking. In vertebrates, a proboscis is an elonga ...

. The digestive tract is a simple tube, usually with a stomach part way along. The smallest species, and those adapted to burrowing, lack

gill A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they ar ...

s, breathing only through their body surfaces. Most other species have external gills, often associated with the parapodia. A simple but well-developed circulatory system is usually present. The two main blood vessels furnish smaller vessels to supply the parapodia and the gut. Blood flows forward in the dorsal vessel, above the gut, and returns down the body in the ventral vessel, beneath the gut. The blood vessels themselves are contractile, helping to push the blood along, so most species have no need of a heart. In a few cases, however, muscular pumps analogous to a heart are found in various parts of the system. Conversely, some species have little or no circulatory system at all, transporting oxygen in the

coelomic fluid The coelom (or celom) is the main body cavity in most animals and is positioned inside the body to surround and contain the digestive tract and other organs. In some animals, it is lined with mesothelium. In other animals, such as molluscs, ...

that fills their body cavities. The blood may be colourless, or have any of three different respiratory pigments. The most common of these is haemoglobin, but some groups have haemerythrin or the green-coloured chlorocruorin, instead. The nervous system consists of a single or double ventral nerve cord running the length of the body, with ganglia and a series of small nerves in each segment. The brain is relatively large, compared with that of other annelids, and lies in the upper part of the head. An endocrine gland is attached to the ventral posterior surface of the brain, and appears to be involved in reproductive activity. In addition to the sensory organs on the head, photosensitive eye spots, statocysts, and numerous additional sensory nerve endings, most likely in involved with the sense of touch, also occur on the body. Polychaetes have a varying number of protonephridia or metanephridia for excreting waste, which in some cases can be relatively complex in structure. The body also contains greenish "chloragogen" tissue, similar to that found in oligochaetes, which appears to function in metabolism, in a similar fashion to that of the vertebrate

liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...

. The cuticle is constructed from cross-linked fibres of collagen and may be 200 nm to 13 mm thick. Their jaws are formed from sclerotised collagen, and their setae from sclerotised

Ecology

Polychaetes are extremely variable in both form and lifestyle, and include a few taxa that swim among the

or above the abyssal plain. Most burrow or build tubes in the sediment, and some live as

s. A few are parasitic. The mobile forms (Errantia) tend to have well-developed sense organs and jaws, while the stationary forms (Sedentaria) lack them, but may have specialized gills or tentacles used for respiration and deposit or filter feeding, e.g., fanworms. Underwater polychaetes have eversible mouthparts used to capture prey. A few groups have evolved to live in terrestrial environments, like Namanereidinae with many terrestrial species, but are restricted to humid areas. Some have even evolved cutaneous invaginations for aerial gas exchange.

Notable polychaetes

*One notable polychaete, the Pompeii worm (''Alvinella pompejana''), is endemic to the hydrothermal vents of the Pacific Ocean. Pompeii worms are among the most heat-tolerant complex animals known. *A recently discovered genus, '' Osedax'', includes a species nicknamed the "bone-eating snot flower". *Another remarkable polychaete is ''

Hesiocaeca methanicola ''Sirsoe methanicola'' is a species of polychaete worm that inhabits methane clathrate deposits in the ocean floor. The worms colonize the methane ice and appear to survive by gleaning bacteria, which in turn metabolize the clathrate. In 1997, ...

'', which lives on methane clathrate deposits. *'' Lamellibrachia luymesi'' is a cold seep tube worm that reaches lengths of over 3 m and may be the most long-lived animal, being over 250 years old. *A still unclassified multilegged predatory polychaete worm was identified only by observation from the underwater vehicle ''Nereus'' at the bottom of the Challenger Deep, the greatest depth in the oceans, near in depth. It was about an inch long visually, but the probe failed to capture it, so it could not be studied in detail. *The Bobbit worm ('' Eunice aphroditois'') is a predatory species that can achieve a length at ), with an average diameter of . *''Dimorphilus gyrociliatus'', which has the smallest known genome of any annelid. The species shows an extreme

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most an ...

, with females measuring just ~1 mm long and has a simplified segmented body with only six segments, reduced coelom, and no appendages, parapodia or chaetae. The males are only 50 µm long, consist of just a few hundred cells, lack a digestive system, only live for about a week and has just 68 neurons.

Reproduction

Most polychaetes have separate sexes, rather than being hermaphroditic. The most primitive species have a pair of gonads in every segment, but most species exhibit some degree of specialisation. The gonads shed immature

gamete A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...

s directly into the body cavity, where they complete their development. Once mature, the gametes are shed into the surrounding water through ducts or openings that vary between species, or in some cases by the complete rupture of the body wall (and subsequent death of the adult). A few species copulate, but most fertilize their eggs externally. The fertilized eggs typically hatch into trochophore larvae, which float among the

, and eventually metamorphose into the adult form by adding segments. A few species have no larval form, with the egg hatching into a form resembling the adult, and in many that do have larvae, the trochophore never feeds, surviving off the yolk that remains from the egg. However, some polychaetes exhibit remarkable reproductive strategies. Some species reproduce by

epitoky Epitoky is a process that occurs in many species of polychaete marine worms wherein a sexually immature worm (the atoke) is modified or transformed into a sexually mature worm (the epitoke). Epitokes are pelagic morphs capable of sexual repro ...

. For much of the year, these worms look like any other burrow-dwelling polychaete, but as the breeding season approaches, the worm undergoes a remarkable transformation as new, specialized segments begin to grow from its rear end until the worm can be clearly divided into two halves. The front half, the atoke, is asexual. The new rear half, responsible for breeding, is known as the epitoke. Each of the epitoke segments is packed with eggs and sperm and features a single eyespot on its surface. The beginning of the last lunar quarter is the cue for these animals to breed, and the epitokes break free from the atokes and float to the surface. The eye spots sense when the epitoke reaches the surface and the segments from millions of worms burst, releasing their eggs and sperm into the water. A similar strategy is employed by the deep sea worm '' Syllis ramosa'', which lives inside a

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate throug ...

. The rear end of the worm develops into a "stolon" containing the eggs or sperm; this stolon then becomes detached from the parent worm and rises to the sea surface, where fertilisation takes place.

Fossil record

Stem-group polychaete fossils are known from the Sirius Passet Lagerstätte, a rich, sedimentary deposit in Greenland tentatively dated to the late

Atdabanian Cambrian Stage 3 is the still unnamed third stage of the Cambrian. It succeeds Cambrian Stage 2 and precedes Cambrian Stage 4, although neither its base nor top have been formally defined. The plan is for its lower boundary to correspond approxi ...

(early

Cambrian The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ag ...

). The oldest found is Phragmochaeta canicularis. Many of the more famous

Burgess Shale The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest fos ...

organisms, such as '' Canadia'', may also have polychaete affinities. '' Wiwaxia'', long interpreted as an annelid, is now considered to represent a mollusc. An even older fossil, '' Cloudina'', dates to the terminal

Ediacaran The Ediacaran Period ( ) is a geological period that spans 96 million years from the end of the Cryogenian Period 635 million years ago (Mya), to the beginning of the Cambrian Period 538.8 Mya. It marks the end of the Proterozoic Eon, and t ...

period; this has been interpreted as an early polychaete, although consensus is absent. Being soft-bodied organisms, the fossil record of polychaetes is dominated by their fossilized jaws, known as scolecodonts, and the

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ...

ized tubes that some of them secrete. Most important

biomineralising polychaetes Biomineralising polychaetes are polychaetes that Biomineralization, biomineralize. The most important biomineralizing polychaetes are Serpulidae, serpulids, Sabellidae, sabellids and Cirratulidae, cirratulids. They secrete tubes of calcium carb ...

are serpulids, sabellids, and cirratulids. Polychaete cuticle does have some preservation potential; it tends to survive for at least 30 days after a polychaete's death. Although biomineralisation is usually necessary to preserve soft tissue after this time, the presence of polychaete muscle in the nonmineralised Burgess shale shows this need not always be the case. Their preservation potential is similar to that of

jellyfish Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella- ...

Taxonomy and systematics

Taxonomically, polychaetes are thought to be

, meaning the group excludes some descendants of its most recent common ancestor. Groups that may be descended from the polychaetes include the oligochaetes (

earthworm An earthworm is a terrestrial invertebrate that belongs to the phylum Annelida. They exhibit a tube-within-a-tube body plan; they are externally segmented with corresponding internal segmentation; and they usually have setae on all segments. ...

s and

leech Leeches are segmented parasitic or predatory worms that comprise the subclass Hirudinea within the phylum Annelida. They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular segmented b ...

es), 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 In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...

have been subject to

cladistic Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived ch ...

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 Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

or ''

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...

'' **Family Diurodrilidae **Family Histriobdellidae **Family Nerillidae **Family

Parergodrilidae Parergodrilidae is an enigmatic family of polychaetes with only two genera, one living on the coast, the other terrestrial. They share much in common with the clitellates, but molecular data place them with Questa and Orbiniidae Orbiniidae i ...

**Family Potamodrilidae **Family

Psammodrilidae Psammodrilidae is a family of polychaetes belonging to the order Spionida Spionida is an order of marine polychaete worms in the infraclass Canalipalpata. Spionids are cosmopolitan and live in soft substrates in the littoral or neritic zones. ...

**Family Spintheridae **Family

Protodriloididae ''Protodriloides'' is a genus of polychaetes belonging to the monotypic family Protodriloididae. The species of this genus are found in Europe and Northern America. Species: *''Protodriloides chaetifer'' *''Protodriloides symbioticus'' Refer ...

**Family Saccocirridae **Order

Haplodrili Haplodrili, or Archiannelida, is an order of primitive polychaete worms. Zoologist Ray Lankester gave it the name haplodrili, while zoologist Berthold Hatschek later named it Archiannelida. Once considered to be a class under Annelida, and even ...

**Order Myzostomida ***Family

Endomyzostomatidae Endomyzostomatidae is a family of polychaetes belonging to the order Myzostomida The Myzostomida or Myzostomatida are an order of small marine worms, which are parasitic on echinoderms, mostly crinoids. These highly unusual and diverse anneli ...

***Family Asteromyzostomatidae ***Family

Myzostomidae Myzostomatidae is a family of polychaetes belonging to the order Phyllodocida. Genera: * '' Asteromyzostomum'' Vagin, 1954 * '' Cystimyzostomum'' Jagersten, 1940 * '' Endomyzostoma'' * '' Hypomyzostoma'' Perrier, 1897 * '' Mesomyzostoma'' Remsch ...

*Subclass Palpata **Family

Protodrilidae Protodrilidae is a family of polychaetes belonging to the order Protodrilida Protodrilida is an order of polychaetes belonging to the class Polychaeta Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly call ...

**Family

Polygordiidae Polygordiidae is a family of polychaetes belonging to the class Polychaeta Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy prot ...

*Subclass Aciculata **Family Levidoridae **Order

Amphinomida Amphinomida is an order of marine polychaetes. The order contains two families: * '' Amphinomidae'' Lamarck, 1818 * '' Euphrosinidae'' Williams, 1852 References Polychaetes {{annelid-stub ...

***Family Amphinomidae ***Family Euphrosinidae **Order Eunicida ***Family Dorvilleidae ***Family Eunicidae ***Family

Hartmaniellidae Hartmaniellidae is a family of polychaetes belonging to the order Eunicida Eunicida is an order of polychaete worms. Characteristics Members of this order have an elongated, segmented body and a distinct head, normally with a separate peristo ...

***Family

Ichthyotomidae Ichthyotomidae is a family of polychaetes belonging to the order Phyllodocida Phyllodocida is an order of polychaete worms in the subclass Aciculata. These worms are mostly marine, though some are found in brackish water. Most are active benth ...

***Family Lumbrineridae ***Family

Oenonidae Oenonidae is a family of polychaetes belonging to the order Eunicida Eunicida is an order of polychaete worms. Characteristics Members of this order have an elongated, segmented body and a distinct head, normally with a separate peristomium a ...

***Family Onuphidae **Order Phyllodocida ***Suborder Aphroditiformia ****Family

Acoetidae Acoetidae is a family of polychaete worms in the subclass Aciculata. Genera * '' Acoetes'' Audouin & Milne Edwards, 1832 * '' Euarche'' Ehlers, 1887 * '' Eumolpe'' * '' Eupanthalis'' McIntosh, 1876 * '' Eupolyodontes'' Buchanan, 1894 * '' Eup ...

****Family

Aphroditidae Aphroditidae is a family of annelids belonging to the order Phyllodocida. Genera Genera: * ''Aphrodita ''Aphrodita'' is a genus of ocean, marine polychaete worms found in the Mediterranean sea and the eastern and western Atlantic Ocean. S ...

****Family

Eulepethidae Eulepethidae is a family of polychaetes belonging to the order Phyllodocida Phyllodocida is an order of polychaete worms in the subclass Aciculata. These worms are mostly marine, though some are found in brackish water. Most are active benthi ...

****Family

Iphionidae Iphionidae is a family of polychaetes belonging to the order Phyllodocida Phyllodocida is an order of polychaete worms in the subclass Aciculata. These worms are mostly marine, though some are found in brackish water. Most are active benthic ...

****Family

Pholoidae Pholoidae is a family of polychaetes belonging to the order Phyllodocida. Genera: * '' Imajimapholoe'' Pettibone, 1992 * '' Laubierpholoe'' Pettibone, 1992 * '' Metaxypsamma'' Wolf, 1986 * ''Pholoe Foloi ( el, Φολόη, Latin: ''Pholoe'') is a ...

****Family Polynoidae ****Family Sigalionidae ***Suborder Glyceriformia ****Family

Glyceridae Glyceridae is a family of polychaete worms. They are commonly referred to as beak-thrower worms or bloodworms. They are bright red, segmented, aquatic worms. The proboscis worm '' Glycera'' is sometimes called bloodworm. The Glyceridae are epi- a ...

****Family Goniadidae ****Family

Lacydoniidae Lacydoniidae is a family of polychaetes belonging to the order Phyllodocida. Genera: * '' Lacydonia'' Marion, 1874 References Polychaetes {{Annelid-stub ...

****Family Paralacydoniidae ***Suborder Nereidiformia ****Family Antonbruunidae ****Family

Chrysopetalidae Chrysopetalidae is a family of polychaete worms. The body is short or elongated, with few or numerous segments. All segments bear on their dorsal side a fan or a transverse row of paleae. The cephalic lobe has tentacles and eyes and the buccal se ...

****Family

Hesionidae Hesionidae are a family of phyllodocid "bristle worms" (class Polychaeta). They are (like almost all polychaetes) marine organisms. Most are found on the continental shelf; '' Hesiocaeca methanicola'' is found on methane ice, where it feeds o ...

****Family Nereididae ****Family Pilargidae ****Family Syllidae ***Suborder

Phyllodocida incertae sedis Phyllodocida is an order of polychaete worms in the subclass Aciculata. These worms are mostly marine, though some are found in brackish water. Most are active benthic creatures, moving over the surface or burrowing in sediments, or living in cra ...

****Family Iospilidae ****Family Nautiliniellidae ****Family

Nephtyidae Nephtyidae is a family of polychaete worms. They are commonly referred to as catworms. Characteristics Nephtyidae are pale, clearly segmented polychaetes with a small pentagonal prostomium with two pairs of small antennae. Their segments are litt ...

****Family

Typhloscolecidae Typhloscolecidae is a family of polychaetes belonging to the order Phyllodocida. Genera: * ''Acicularia ''Acicularia'' is a genus of green algae in the family Dasycladaceae The Dasycladaceae is one of the two extant families of green algae ...

****Family Tomopteridae ***Suborder

Phyllodociformia Phyllodocida is an order of polychaete worms in the subclass Aciculata. These worms are mostly marine, though some are found in brackish water. Most are active benthic creatures, moving over the surface or burrowing in sediments, or living in cr ...

****Family

Alciopidae Alciopidae is a family of polychaetes belonging to the order Phyllodocida Phyllodocida is an order of polychaete worms in the subclass Aciculata. These worms are mostly marine, though some are found in brackish water. Most are active benthic c ...

****Family

Lopadorhynchidae Lopadorrhynchidae is a family of polychaete worms. References External links * Lopadorrhynchidaeat the World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an autho ...

****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 Spionida is an order of marine polychaete worms in the infraclass Canalipalpata. Spionids are cosmopolitan and live in soft substrates in the littoral or neritic zones. Characteristics Spionids have a single pair of flexible feeding tentac ...

****Suborder Spioniformia *****Family Apistobranchidae *****Family Longosomatidae *****Family Magelonidae *****Family Poecilochaetidae *****Family

Spionidae Spionidae is a family of marine worms within the Polychaeta. Spionids are selective deposit feeders that use their two grooved palps Pedipalps (commonly shortened to palps or palpi) are the second pair of appendages of chelicerates – a group ...

*****Family Trochochaetidae *****Family Uncispionidae ***Order Terebellida ****Suborder Cirratuliformia *****Family Acrocirridae (sometimes placed in Spionida) *****Family Cirratulidae (sometimes placed in Spionida) *****Family

Ctenodrilidae Ctenodrilidae is a family of polychaetes belonging to the order Terebellida. Genera: * '' Zeppelina'' Vaillant, 1890 References Terebellida {{Annelid-stub ...

(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 Sternaspidae, commonly known as mud owls, are a family of marine polychaete worms with short swollen bodies. They have a global distribution and live buried in soft sediment at depths varying from the intertidal zone to . Description Members of ...

(sometimes own suborder Sternaspida) ****Suborder

Terebellomorpha Terebelliformia is a group of polychaete Polychaeta () is a paraphyletic class (biology), class of generally marine invertebrate, marine annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair ...

*****Family

Alvinellidae The Alvinellidae are a family of small, deep-sea polychaete worms endemic to hydrothermal vents in the Pacific Ocean. Belonging to the order Terebellida, the family contains two genera, ''Alvinella'' and ''Paralvinella''; the former genus conta ...

*****Family Ampharetidae *****Family Pectinariidae *****Family Terebellidae *****Family

Trichobranchidae Trichobranchidae is a family of annelids in the order Terebellida. It consists of one subfamily, Trichobranchinae, to which all of its genera belong. Genera * '' Octobranchus'' Marion & Bobretzky, 1875Marion, A. & Bobretzky, N. (1875). Étude de ...

**Infraclass Scolecida ***Family

Arenicolidae Arenicolidae is a family of marine polychaete worms. They are commonly known as lugworms and the little coils of sand they produce are commonly seen on the beach. Arenicolids are found worldwide, mostly living in burrows in sandy substrates. Most ...

***Family Capitellidae ***Family

Cossuridae Cossurida is an order of polychaetes belonging to the class Polychaeta. The order is monotypic, consisting of only one family: Cossuridae Day, 1963 References

{{Taxonbar, from1=Q5153411, from2=Q59654245 Polychaetes Annelid families ...

***Family Maldanidae ***Family Opheliidae ***Family Orbiniidae ***Family Paraonidae ***Family Scalibregmatidae ***Order Capitellida ( nomen dubium) ***Order

Cossurida Cossurida is an order of polychaetes belonging to the class Polychaeta Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusi ...

(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

References

Bibliography

* Campbell, Reece, and Mitchell. Biology. 1999. *

Notes

External links

World Polychaeta Database

Special issue of ''Marine Ecology''
dedicated to polychaetes

a guide to the marine zooplankton of south eastern Australia

Natural History Museum A natural history museum or museum of natural history is a scientific institution with natural history collections that include current and historical records of animals, plants, fungi, ecosystems, geology, paleontology, climatology, and more ...

{{Authority control * Extant Cambrian first appearances Paraphyletic groups

Description

Internal anatomy and physiology

Ecology

Notable polychaetes

Reproduction

Fossil record

Taxonomy and systematics

See also

References

Bibliography

Notes

External links