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.

Annelid taxonomy is currently under constant revisions due to the discovery that the class Polychaeta is paraphyletic.

However, it was found that Acanthocephala are phylogenetically contained within the rotifers, and this list reflects these findings.

[citation needed] Superclass Eurotatoria Clade Acanthocephala The class Mesotardigrada contains one species, Thermozodium esakii, which has not been found since its reported discovery in 1937, and its existence is dubious.

The relative number of species contributed to the total by each phylum of animals. Arthropoda is the phylum with the most individual organisms.
Hirudo medicinalis . Order Arhynchobdellida
The house fly . Order Diptera
Terebratalia transversa . Order Terebratulida
A colony of Membranipora membranacea . Order Cheilostomatida
Spadella cephaloptera . Order Phragmophora
The great white shark . Order Lamniformes
Symbion americanus . Order Symbiida
Dicyema japonicum
Asterias rubens . Order Forcipulatida
A colony of Barentsia ramosa
Paradasys subterraneus . Order Macrodasyida
Gnathostomula paradoxa . Order Bursovaginoidea
Unknown species of acorn worm (class Enteropneusta).
Echinoderes marthae . Order Echinorhagata
Spinoloricus cinziae . Order Nanaloricida
Limnognathia maerski . Order Limnognathida
Sepioteuthis sepioidea . Order Myopsida
Caenorhabditis elegans . Order Rhabditida
Paragordius tricuspidatus . Order Gordioidea
Baseodiscus quinquelineatus . Order Heteronemertea
Epiperipatus biolleyi
A drawing of Rhopalura giardii
Phoronopsis harmeri
Pseudoceros ferrugineus . Order Polycladida
Priapulus caudatus . Order Priapulimorphida
Habrotrocha rosa . Order Philodinida
Acutuncus antarcticus . Order Parachela
Neochildia fusca . Order Acoela