# List of bilaterian orders

Bilateria is an extremely diverse group of animals containing a vast majority of its species, largely due to the enormous amount of arthropods. This article is a list of orders contained within Bilateria separated by phylum. Groups that are not contained within an order are listed separately.

## List
### Phylum Annelida

Annelid taxonomy is currently under constant revisions due to the discovery that the class Polychaeta is paraphyletic. As such, a comprehensive list of orders is likely to change depending on what is accepted as valid.
* Amphinomida
Class Sipuncula
* Aspidosiphonida
* Golfingiida
* Phascolosomatida
Clade Pleistoannelida
* Clade Errantia
** Eunicida
** Phyllodocida
** Protodrilida
* Myzostomida
* Clade Sedentaria
** Capitellida
*** Family Capitellidae
*** Subclass Echiura
**** Bonelliida
**** Echiurida
** Opheliida
** Orbiniida
** Sabellida
** Spionida
** Terebellida
** Class Clitellata
*** Branchiobdellida
*** Haplotaxida
*** Lumbriculida
*** Moniligastrida
*** Subclass Hirudinea
**** Rhynchobdellida
**** Arhynchobdellida
Unplaced groups
* Genus Apistobranchus
* Suborder Chaetopteriformia
* Suborder Cirratuliformia
* Genus Lobatocerebrum
* Clade Maldanomorpha
* Clade Paleoannelida
* Family Polygordiidae
* Family Siboglinidae

### Phylum Arthropoda

See List of arthropod orders

### Phylum Brachiopoda

Class Craniata
* Craniida
* Craniopsida †
* Trimerellida †
Subphylum Linguliformea
* Class Lingulata
** Acrotretida †
** Lingulida
** Siphonotretida †
* Class Paterinata
** Paterinida †
Subphylum Rhynchonelliformea
* Class Chileata
** Chileida †
** Dictyonellida †
* Class Kutorginata
** Kutorginida †
* Class Obolellata
** Naukatida †
** Obolellida †
* Class Rhynchonellata
** Athyridida †
** Atrypida †
** Orthida †
** Protorthida †
** Pentamerida †
** Rhynchonellida
** Spiriferida †
** Terebratulida
** Thecideida
* Class Strophomenata
** Billingsellida †
** Orthotetida †
** Productida †
** Strophomenida †

### Phylum Bryozoa

Class Gymnolaemata
* Cheilostomata
* Ctenostomatida
Class Phylactolaemata
* Plumatellida
Class Stenolaemata
* Cyclostomatida
* Cryptostomata †
* Cystoporida †
* Esthonioporata †
* Fenestrata †
* Timanodictyina †
* Trepostomatida †

### Phylum Chaetognatha

* Aphragmophora
* Phragmophora
* Protoconodonta †
Unplaced groups
* Genus Capinatator
* Genus Eognathacantha
* Genus Protodagitta
* Genus Timorebestia

### Phylum Chordata

See List of chordate orders

### Phylum Cycliophora

Class Eucycliophora
* Symbiida

### Phylum Dicyemida

Dicyemida does not contain any established orders but does contain three families: Conocyemidae, Dicyemidae and Kantharellidae

### Phylum Echinodermata

See List of echinoderm orders

### Phylum Entoprocta

Entoprocta has no orders but is split into four families; Barentsiidae, Pedicellinidae, Loxokalypodidae, and Loxosomatidae

### Phylum Gastrotricha

* Chaetonotida
* Macrodasyida

### Phylum Gnathostomulida

* Bursovaginoidea
* Filospermoidea

### Phylum Hemichordata

The classes Planctosphaeroidea and Enteropneusta do not contain any orders
Class Pterobranchia
* Cephalodiscida
* Subclass Graptolithina
** Rhabdopleurida
** Dendroidea †
** Graptoloidea †
Unplaced groups
* Family Cysticamaridae
* Family Wimanicrustidae
* Family Dithecodendridae
* Family Cyclograptidae

### Phylum Kinorhyncha

Class Cyclorhagida
* Echinorhagata
* Kentrorhagata
* Xenosomata
Class Allomalorhagida
* Anomoirhaga
Unplaced groups
* Genus Eokinorhynchus
* Family Pycnophyidae

### Phylum Loricifera

Loricifera has no classes and all species are contained within one order
* Nanaloricida

### Phylum Micrognathozoa

Micrognathozoa has no classes and its single species is placed in one order
* Limnognathida

### Phylum Mollusca

See List of mollusc orders

### Phylum Nematoda

Nematode taxonomy is far from fully resolved, and different schemes might be used. For this list, Mike Hodda's Phylum Nematoda: a classification, catalogue and index of valid genera, with a census of valid species classification is used.
Class Enoplea
* Subclass Enoplia
** Superorder Enoplica
*** Alaimida
*** Enoplida
*** Ironida
*** Trefusiida
*** Tripyloidida
** Superorder Rhaptothyreica
*** Rhaptothyreida
* Subclass Oncholaimia
** Oncholaimida
* Subclass Triplonchia
** Triplonchida
** Tripylida
Class Dorylaimea
* Subclass Dorylaimia
** Dorylaimida
* Subclass Bathyodontia
** Bathyodontida
** Mononchida
** Mermithida
* Subclass Trichocephalia
** Trichocephalida
** Marimermithida
** Dioctophymatida
** Muspiceida
Class Chromadorea
* Subclass Chromadoria
** Chromadorida
** Selachinematida
** Desmodorida
** Desmoscolecida
* Subclass Plectia
** Superorder Monhysterica
*** Monhysterida
** Superorder Plectica
*** Leptolaimida
*** Plectida
*** Benthimermithida
** Superorder Teratocephalica
*** Teratocephalida
** Superorder Rhabditica
*** Diplogasterida
*** Rhabditida
*** Spirurida
*** Rhigonematida
*** Panagrolaimida
*** Drilonematida

### Phylum Nematomorpha

* Gordioidea
* Nectonematoidea

### Phylum Nemertea

Class Hoplonemertea
* Monostilifera
* Polystilifera
Class Palaeonemertea
* Archinemertea
* Carinomiformes
* Tubulaniformes
Class Pilidiophora
* Heteronemertea

### Phylum Onychophora

Onychophora contains no classes and no orders, but is split into two living families; Peripatidae and Peripatopsidae, and 5 extinct genera; Antennacanthopodia, Antennipatus, Helenodora, Succinipatopsis, and Tertiapatus.

### Phylum Orthonectida

Orthonectida contains no classes or orders, but is split into two families; Pelmatosphaeridae and Rhopaluridae

### Phylum Phoronida

Phoronida contains no classes, orders, or families, but is split into two genera; Phoronis and Phoronopsis

### Phylum Platyhelminthes

The class Catenulida contains no orders.
Subphylum Rhabditophora
* Clade Macrostomorpha
** Macrostomida
* Clade Trepaxonemata
** Gnosonesimida
** Clade Amplimatricata
*** Lecithoepitheliata
*** Polycladida
** Clade Euneoophora
*** Proseriata
*** Rhabdocoela
*** Clade Acentrosomata
**** Clade Adiaphanida
***** Prolecithophora
***** Fecampiida
***** Tricladida
**** Clade Bothrioneodermata
***** Bothrioplanida
***** Superclass Neodermata
****** Class Cestoda
******* Subclass Cestodaria
******** Amphilinidea
******** Gyrocotylidea
******* Subclass Eucestoda
******** Spathebothriidea
******** Caryophyllidea
******** Haplobothriidea
******** Diphyllobothriidea
******** Diphyllidea
******** Trypanorhyncha
******** Bothriocephalidea
******** Litobothriidea
******** Lecanicephaloidea
******** Rhinebothriidea
******** Tetraphyllidea
******** Onchoproteocephalidea
******** Nippotaeniidea
******** Tetrabothriidea
******** Cyclophyllidea
****** Class Monogenea
******* Subclass Monopisthocotylea
******** Monocotylidea
******** Capsalidea
******** Lagarocotylidea
******** Montchadskyellidea
******** Gyrodactylidea
******** Dactylogyridea
******* Subclass Polyopisthocotylea
******** Polystomatidea
******** Chimaericolidea
******** Diclybothriidea
******** Mazocraeidea
****** Class Trematoda
******* Subclass Aspidogastrea
******** Aspidogastrida
******** Stichocotylida
******* Subclass Digenea
******** Diplostomida
******** Plagiorchiida
Unplaced groups
* Genus Haplopharynx

### Phylum Priapulida

Several stem group priapulid genera are not classified within any established orders. The orders listed below are solely crown priapulids.
* Halicryptomorphida
* Priapulimorphida
* Meiopriapulomorpha
* Seticoronaria

### Phylum Rotifera

The group Acanthocephala is traditionally treated as a separate phylum from Rotifera. However, it was found that Acanthocephala are phylogenetically contained within the rotifers, and this list reflects these findings.
* Seisonida
Superclass Eurotatoria
* Class Bdelloidea
** Adinetida
** Philodinavida
** Philodinida
* Class Monogononta
** Collothecaceae
** Flosculariaceae
** Ploima
Clade Acanthocephala
* Class Archiacanthocephala
** Apororhynchida
** Gigantorhynchida
** Moniliformida
** Oligacanthorhynchida
* Class Eoacanthocephala
** Gyracanthocephala
** Neoechinorhynchida
* Class Palaeacanthocephala
** Echinorhynchida
** Heteramorphida
** Polymorphida
* Polyacanthorhynchida

### Phylum Tardigrada

The class Mesotardigrada contains one species, Thermozodium esakii, which has not been found since its reported discovery in 1937, and its existence is dubious. It is contained within the order Thermozodia.
* Class Eutardigrada
** Apochela
** Parachela
* Class Heterotardigrada
** Arthrotardigrada
** Echiniscoidea

### Phylum Xenacoelomorpha

The subphylum Xenoturbellida does not contain any classes or orders. It's only family is Xenoturbellidae which contains one genus, Xenoturbella.
* Subphylum Acoelomorpha
** Acoela
The class Nemertodermatida does not contain any orders, but does contain two families; Ascopariidae and Nemertodermatidae.