This List of echinoderm orders concerns the various classes and orders into which

taxonomists In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given ...

categorize the roughly 7000 extant species as well as the extinct

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

of the exclusively marine phylum

Echinodermata An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the s ...

Subphylum
Crinozoa Crinozoa is a subphylum of mostly sessile echinoderms, of which the crinoids, or sea lilies, are the only extant members. Crinozoans have an extremely extensive fossil history, which may or may not extend into the Precambrian (provided the enigma ...

Class
Crinoidea Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which ar ...

Crinoid on the reef of Batu Moncho Island

* Subclass Articulata (540 species) ** Order

Bourgueticrinida Bourgueticrinida is an order of crinoids that typically live deep in the ocean. Members of this order are attached to the seabed by a slender stalk and are known as sea lilies. While other groups of crinoids flourished during the Permian, bourgu ...

** Order

Comatulida Comatulida is an order of crinoids. Members of this order are known as feather stars and mostly do not have a stalk as adults. The oral surface with the mouth is facing upwards and is surrounded by five, often divided rays with feathery pinnules ...

** Order

Cyrtocrinida Cyrtocrinida is an order of sea lilies which contains two suborders and three families. Characteristics Members of this order have stems consisting of a single skeletal unit or a very small number of units. There are no cirri, and the expanded ...

** Order Hyocrinida ** Order

Isocrinida Isocrinida is an order of sea lilies which contains four extant families. Characteristics Members of this order are characterised by having a "heteromorphic" stalk; the stalk consists of a series of nodes with cirri, interspersed by several node ...

** Order

Millericrinida Millericrinida is an order of articulate crinoids that originated in the Anisian In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from million years ago until millio ...

* Subclass †

Flexibilia Flexibilia is a superorder of specialized Paleozoic (Middle Ordovician to Permian) crinoids. They exhibited a conserved body plan and consistent suite of characteristics throughout their long history. Previously considered a subclass with unclea ...

* Subclass † Camerata * Subclass †

Disparida Disparida is an parvclass of extinct marine animals in the class Crinoidea. Disparids are a speciose and morphologically diverse group of crinoids distinguished by their monocyclic calyx and slender arms without pinnules. They range from the Ea ...

Image:Comaster schlegelii.JPG, '' Comaster schlegelii'' (

) Image:Holopus 2.jpg, ''

Holopus ''Holopus'' is a genus of echinoderms belonging to the family Holopodidae. The species of this genus are found in Central America, Pacific Ocean (near Australia). Species: *''Holopus alidis'' *''Holopus mikihe'' *''Holopus rangii'' Referenc ...

sp.'' (

) Image:Encrinus liliiformis 4.JPG, '' Encrinus liliiformis'' ( Encrinida) Image:Calamocrinus diomedæ (Plate XXVIII) BHL4232451.jpg, '' Calamocrinus diomedae'' ( Hyocrinida) Image:Proisocrinus ruberrimus.jpg, '' Proisocrinus ruberrimus'' (

) Image:Liliocrinus polydactylus MHNT.jpg, '' Liliocrinus polydactylus'' (

)

Class
Paracrinoid Paracrinoidea is an extinct class of blastozoan echinoderms. They lived in shallow seas during the Early Ordovician through the Early Silurian. While blastozoans are usually characterized by types of respiratory structures present, it is not cle ...
ea †

No orders, 13 to 15 genera are known. * order Comarocystitida † ** ?Family Heckeritidae † *** '' Heckerites'' † ** Family Amygdalocystitidae † *** '' Achradocystites'' † Volborth, 1870 *** '' Amygdalocystites'' † Billings, 1854 (= ''Ottawacystis'') (?= ''Billingsocystis'') *** '' Oklahomacystis'' † Parsley & Mintz, 1975 (Bassler, 1943) *** '' Ovulocystites'' † Frest et al., 1980 ** Family Comarocystitidae † Balther, 1899 *** '' Comarocystites'' † Billings, 1854 *** '' Implicaticystis'' † *** '' Sinclairocystis'' † * order Platycystitida † ** Family Platycystitidae † *** '' Canadocystis'' † (= ''Sigmacystis'') *** '' Platycystites'' † ** Family Malocystitidae † *** '' Malocystites'' † *** '' Wellerocystis'' † ** Family Bistomiacystitidae † *** '' Bistomiacystis'' † Doubtful paracrinoids: * ''Columbocystis'' * ''Foerstecystis'' * ''Springerocystis'' * ''Ulrichocystis'' * ''Paleocystites'' * ''Allocystites''

Class
Cystoidea Cystoidea is a class of extinct crinozoan echinoderms, termed cystoids, that lived attached to the sea floor by stalks. They existed during the Paleozoic Era, in the Middle Ordovician and Silurian Periods, until their extinction in the Devo ...
†

* order Aristocystitida † * order Asteroblastida † * order Glyptosphaeritida † * order Sphaeronitida †

Class
Edrioasteroidea Edrioasteroidea is an extinct class of echinoderms. The living animal would have resembled a pentamerously symmetrical disc or cushion. They were obligate encrusters and attached themselves to inorganic or biologic hard substrates (frequently h ...
†

* order Edrioasterida * order Isorophida

Subphylum
Asterozoa The Asterozoa are a subphylum in the phylum Echinodermata. Characteristics include a star-shaped body and radially divergent axes of symmetry. The subphylum includes the class Asteroidea (the starfish), the class Ophiuroidea (the brittle stars ...

Class Ophiuroidea (
Brittle star Brittle stars, serpent stars, or ophiuroids (; ; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms for locomot ...
s)

** Order

Euryalida The Euryalida are an order of brittle stars, which includes large species with either branching arms (called "basket stars") or long and curling arms (called "snake stars"). Characteristics Many of the species in this order have characteristi ...

** Order

Ophiurida The Ophiurida are an order of echinoderms within the class Ophiuroidea. It includes the vast majority of living brittle stars. Characteristics Ophiurida have bursae for respiration and excretion, and dorsal and ventral arm shields are present a ...

** Order Amphilepidida ** Order

Ophiacanthida Ophiacanthida is an order of echinoderms belonging to the class Ophiuroidea. Families: * Ophiodermatina Ljungman, 1867 ** Ophiodermatidae ** Ophiomyxidae ** Ophiopezidae ** Ophiocomidae Ophiocomidae are a family of brittle stars of the subo ...

** Order Ophioleucida ** Order

Ophioscolecida Ophioscolecida is an order of echinoderms belonging to the class Ophiuroidea Brittle stars, serpent stars, or ophiuroids (; ; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to ...

Image:Basket star feeding at night at the Red Sea.JPG, '' Astroboa nuda'' (

) Image:Ophiura ophiura.jpg, ''

Ophiura ophiura ''Ophiura ophiura'' or the serpent star is a species of brittle star in the order Ophiurida. It is typically found on coastal seabeds around northwestern Europe. Description ''Ophiura ophiura'' has a circular central disc up to 35 mm (1.5 ...

'' (

) Image:Ophiolepis elegans 600.jpg, '' Ophiolepis elegans'' ( Amphilepidida) Image:Ophiure noire à la Réunion.JPG, ''

Ophiocoma erinaceus ''Ophiocoma erinaceus'' is a species of echinoderms belonging to the family Ophiocomidae Ophiocomidae are a family of brittle stars of the suborder Ophiurina. Systematics and phylogeny Ophiocomidae has been placed (along with Ophionereididae) ...

'' (

) Image:Ophioleuce seminudum (MNHN-IE-2013-10292) 02.jpg, ''

Ophioleuce seminudum ''Ophioleuce'' is a genus of brittle star Brittle stars, serpent stars, or ophiuroids (; ; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the s ...

'' ( Ophioleucida) Image:Ophiomyces frutectosus (MNHN-IE-2013-10282) 02.jpg, '' Ophiomyces frutectosus'' (

)

Class Asteroidea (
Starfish Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish a ...
)

*Infraclass Concentricycloidea ** Peripodida *Superorder

Forcipulatacea The Forcipulatacea are a superorder of sea stars. Subdivision * order Forcipulatida * order Brisingida The Brisingids are deep-sea-dwelling starfish in the order Brisingida. Description These starfish have between 6 to 18 long, attenuated ...

** Brisingida **

Forcipulatida The Forcipulatida are an order of sea stars, containing three families and 49 genera. Description Forcipulatids share with the brisingid sea stars distinctive pedicellariae, consisting of a short stalk with three skeletal ossicles. Unlike that ...

*Superorder Spinulosacea ** Spinulosida *Superorder Valvatacea **

Notomyotida Benthopectinidae is a family of sea stars containing at least 75 species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is oft ...

** Paxillosida ** Valvatida * Velatida * † Calliasterellidae * † Trichasteropsida Image:Xyloplax janetae.jpg, ''

Xyloplax janetae ''Xyloplax janetae'' is a ''Xyloplax'' of the family Xyloplacidae. It lives on the surface of wood sunken to abyssal depths. Morphology ''Xyloplax janetae'' is a flattened disk, from in diameter, and about thick. It has adambulacral spines wh ...

'' ( Peripodida) Image:Brisingid Seastar (Novodinia antillensis).jpg, '' Novodinia antillensis'' ( Brisingida) Image:Starfish, Oregon coast.jpg, ''

Pisaster ochraceus ''Pisaster ochraceus'', generally known as the purple sea star, ochre sea star, or ochre starfish, is a common seastar found among the waters of the Pacific Ocean. Identified as a keystone species, ''P. ochraceus'' is considered an important in ...

'' (

) Image:Echinaster sepositus Banyuls 03.jpg, '' Echinaster sepositus'' ( Spinulosida) Image:Cheiraster echinulatus.jpg, '' Cheiraster echinulatus'' (

) Image:Astropecten aranciacus Sardegna09 28cm 5520.jpg, ''

Astropecten aranciacus ''Astropecten aranciacus'', the red comb star, is a sea star of the family Astropectinidae. It is native to the east Atlantic Ocean (Portugal to Angola) and Mediterranean Sea. Habitat and behaviour ''Astropecten aranciacus'' lives very near the ...

'' ( Paxillosida) Image:Linckia laevigata Tonga.jpg, '' Linckia laevigata'' ( Valvatida) Image:Euretaster insignis.jpg, '' Euretaster insignis'' ( Velatida)

Subphylum Echinozoa

Class Echinoidea (
Sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) o ...
s)

** Order Diadematoida ** Order

Echinothurioida The Echinothurioida are an order of sea urchins in the class Echinoidea. Echinothurioids are distinguished from other sea urchins by the combination of a flexible test and hollow spines. The membrane around the mouth contains only simple plates ...

** Order Pedinoida * Superorder Echinacea ** Order

Arbacioida Arbacioida are an order of sea urchins, consisting of a single family, the Arbaciidae. They are distinguished from other sea urchins by the presence of five separate plates around the anus. Unlike their close relatives, the Salenioida, all of the ...

** Order

Echinoida Echinoida is an order of sea urchins in the class Echinoidea. They are distinguished from other sea urchins by simultaneously possessing both an un-sculpted test and a feeding lantern with large plates fused across the top of each pyramid. Taxon ...

** Order

Phymosomatoida The Phymosomatoida are an order of sea urchins, found in Europe, North America, North Africa and the Middle East. They are distinguished from other sea urchins by the presence of large fused plates on top of the feeding lantern. The test is usu ...

** Order

Salenioida The Salenioida are an order of sea urchins. Description and characteristics They are distinguished from other sea urchins by the presence of a large plate on the upper surface, with the anus to one side. They have very large tubercles between ...

** Order Temnopleuroida * Superorder

Gnathostomata Gnathostomata (; from Greek: (') "jaw" + (') "mouth") are the jawed vertebrates. Gnathostome diversity comprises roughly 60,000 species, which accounts for 99% of all living vertebrates, including humans. In addition to opposing jaws, livi ...

** Order

Clypeasteroida Sand dollars (also known as a sea cookie or snapper biscuit in New Zealand, or pansy shell in South Africa) are species of flat, burrowing sea urchins belonging to the order Clypeasteroida. Some species within the order, not quite as flat, are k ...

(sand dollars) ** Order

Holectypoida The Holectypoida are an order of sea urchins related to the sand dollar Sand dollars (also known as a sea cookie or snapper biscuit in New Zealand, or pansy shell in South Africa) are species of flat, burrowing sea urchins belonging to the ...

* Superorder

Atelostomata The Atelostomata are a type of sea urchins. They are distinguished from other sea urchins by their irregular shape and the absence of a feeding lantern. The group includes the well known heart urchins, as well as some less familiar and extinct ...

** Order

Holasteroida Holasteroida is an order of irregular sea urchins. Characteristics These irregular sea urchins are characterized by a particularly marked bilateral symmetry, including for the apical system, which is highly elongated. In some contemporary aby ...

** Order

Spatangoida The heart urchins or Spatangoida are an order of sea urchins. Their body is a somewhat elongated oval in form, and is distinguished by the mouth being placed towards one end of the animal, and the anus towards the other. As a result, heart urchi ...

(heart urchins) Image:Aspidodiadema arcitum.jpg, ''

Aspidodiadema hawaiiense ''Aspidodiadema hawaiiense'' is a species of sea urchin of the family Aspidodiadematidae. Their armor is covered with spines. It is placed in the genus Aspidodiadema and lives in the sea. Aspidodiadema hawaiiense was first scientifically describ ...

'', an

Aspidodiadematoida The Aspidodiadematidae are a family of sea urchins. Characteristics All the members of the two extant genera, ''Aspidodiadema'' and ''Plesiodiadema'', are found in tropical seas at bathyal and abyssal depths, often on the submarine slopes of i ...

Image:Diadema antillarum Flower Garden Banks.jpg, ''

Diadema antillarum ''Diadema antillarum'', also known as the lime urchin, black sea urchin, or the long-spined sea urchin, is a species of sea urchin in the family Diadematidae. This sea urchin is characterized by its exceptionally long black spines. It is t ...

'', a Diadematoida Image:Caenopedina hawaiiensis.jpg, '' Caenopedina hawaiiensis'', a Pedinoida Image:Salenocidaris hastigera.png, '' Salenocidaris hastigera'', a

Image:Arbacia lixula (oursin noir).JPG, '' Arbacia lixula'', an

Image:Strongylocentrotus franciscanus at Telegraph Cove.jpg, ''

Strongylocentrotus franciscanus The red sea urchin (''Mesocentrotus franciscanus'') is a sea urchin found in the northeastern Pacific Ocean from Alaska to Baja California. It lives in shallow waters from the low-tide line to greater than deep, and is typically found on rocky ...

'', a

Camarodonta The Camarodonta are an order of globular sea urchins in the class Echinoidea. The fossil record shows that camarodonts have been in existence since the Lower Cretaceous.Stomopneustes variolaris'', a Stomopneustoida Image:Toxic Leather Sea Urchin - Asthenosoma marisrubri.jpg, '' Asthenosoma marisrubri'', an

Image:Pourtalesia wandeli.png, ''

Pourtalesia wandeli ''Pourtalesia'' is a genus of the family Pourtalesiidae which belongs to the irregular ( bilaterally symmetrical) sea urchins. The animals measure 5–6 cm in length and live in the abyssal zone of the Atlantic, Pacific, Indopacific ...

'', a

Image:Tiny maretia heart urchin (Maretia planulata).jpg, '' Maretia planulata'', a

Image:Echinoneus cyclostomus.jpg, '' Echinoneus cyclostomus'', an

Echinoneoida Echinoneoida is an order of echinoderms belonging to the class Echinoidea Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone ...

Image:Clypeaster reticulatus.jpg, ''

Clypeaster reticulatus ''Clypeaster reticulatus'', the reticulated sea biscuit, is a species of sea urchin in the Family Clypeasteridae. This species was first scientifically described in 1758 by Carl Linnaeus. It lives on the sandy seabed of shallow seas, semi-immer ...

'', a

Image:Echinolampas depressa.png, '' Echinolampas depressa'', an Echinolampadoida Image:Eucidaris metularia à la Réunion.jpg, '' Eucidaris metularia'', a Cidaroida

Class Holothuroidea (
Sea cucumber Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothuri ...
s)

** Order Apodida ** Order

Dendrochirotida Dendrochirotida are an order of sea cucumbers. Members of this order have branched tentacles and are suspension feeders. Examples include '' Thyonella'' and ''Cucumaria''. Characteristics Holothurians in this order are characterised by ten to thi ...

** Order Elasipodida ** Order Holothuriida ** Order Molpadida ** Order

Persiculida Persiculida is an order of sea cucumbers. Taxa within the order Persiculida were previously classified in an order called Aspidochirotida, which was determined to be polyphyletic A polyphyletic group is an assemblage of organisms or other e ...

** Order

Synallactida Synallactida is a rankless clade of sea cucumbers, but is referred to as an order. Taxa within Synallactida were previously classified in an order called Aspidochirotida, which was determined to be polyphyletic in 2017. List of families Syna ...

{{clr Image:Euapta godeffroyi1.jpg, ''

Euapta godeffroyi ''Euapta godeffroyi'', the sticky snake sea cucumber, is a species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defi ...

'' ( Apodida) Image:Cercodemas anceps Red box sea cucumber PC260152.JPG, '' Cercodemas anceps'' (

) Image:Scotoplanes globosa and crab.jpg, ''

Scotoplanes globosa ''Scotoplanes globosa,'' commonly known as the sea pig, is a species of sea cucumber that lives in the deep sea. It was first described by Hjalmar Théel, a Swedish scientist. ''Scotoplanes globosa'', along with numerous other sea cucumbers wer ...

'' ( Elasipodida) Image:Holothuria cinerascens Réunion.jpg, '' Holothuria cinerascens'' ( Holothuriida) Image:See-through sea cucumber (Paracaudina australis).jpg, '' Paracaudina australis'' ( Molpadida) Image:Hansenothuria benti.png, '' Hansenothuria benti'' (

) Image:Stichopus herrmanni (Mayotte).jpg, '' Stichopus herrmanni'' (

)

Class
Ophiocistioidea The Ophiocistioidea is a class of extinct echinoderms from the Palaeozoic and early Mesozoic. Ophiocistioids had a flattened dome-shaped body encased in a solid test of calcareous plates, similar to that of a modern sea urchin. The mouth was at ...
†

No orders recognized: class is divided up into four families, Eucladiidae, Sollasiniidae, Volchoviidae, and Rhenosquamidae. The inclusion of Rhenosquamidae within Ophiocistioidea is doubtful, as the organs identified in fossils of '' Rhenosquamus'' as the characteristic "scaly podia" otherwise diagnostic of ophiocistioids may not, in fact, be such structures.

Class
Helicoplacoidea Helicoplacoidea is an extinct class within the Echinodermata. All known taxa were discovered in sediments dating back to the Cambrian.
†

No known orders, 2 known species, ''Helicoplacus curtisi'' and ''H. guthi''

Subphylum
Blastozoa Blastozoa is a subphylum of extinct animals belonging to Phylum Echinodermata. This subphylum is characterized by the presence of specialized respiratory structures and brachiole plates used for feeding. This subphylum ranged from the Cambrian to ...

Class
Blastoidea Blastoids (class Blastoidea) are an extinct type of stemmed echinoderm, often referred to as sea buds. They first appear, along with many other echinoderm classes, in the Ordovician period, and reached their greatest diversity in the Mississi ...
†

* Ordre Coronata † * Order Fissiculata † * Order Spiraculata † * basal '' Macurdablastus'' †

Class
Eocrinoidea The Eocrinoidea are an extinct class of echinoderms that lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, arm-bearing echinoderms, and were the most common echinoderms during the Cambrian. ...
†

* Order Ascocystida † * Order

Gogiida The Gogiida are an order of early echinoderms known from late Early to Middle Cambrian deposits. References Fossil taxa described in 1982 Cambrian first appearances Cambrian extinctions Blastozoa Prehistoric animal orders Echinoderm or ...

† * Order Imbricata † * Order Trachelocrinida †

Subphylum Homostelea /
Homalozoa Homalozoa is an obsolete extinct subphylum of Paleozoic era echinoderms, prehistoric marine invertebrates. They are also referred to as carpoids. Description The Homalozoa lacked the typical pentamer body form of other echinoderms, but all were ...
†

Class
Ctenocystoidea Ctenocystoidea is an extinct clade of echinoderms, which lived during the Cambrian and Ordovician periods. Unlike other echinoderms, ctenocystoids had bilateral symmetry, or were only very slightly asymmetrical. They are believed to be one of the ...
†

** order Ctenocystida †

Class Soluta †

Class
Cincta Cincta is an extinct class of echinoderms that lived only in the Middle Cambrian epoch. Homostelea is a junior synonym. The classification of cinctans is controversial, but they are probably part of the echinoderm stem group. Cinctans were sessi ...
†

Class
Stylophora The stylophorans are an extinct, possibly polyphyletic group allied to the Paleozoic Era echinoderms, comprising the prehistoric cornutes and mitrates. It is synonymous with the subphylum Calcichordata. Their unusual appearances have led to a ...
†

** order

Cornuta Cornuta is an extinct order of echinoderms. Along with the mitrates, they form one half of the Stylophora The stylophorans are an extinct, possibly polyphyletic group allied to the Paleozoic Era echinoderms, comprising the prehistoric co ...

† ** order Mitrata †

References

List

Orders Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of ...

Subphylum Crinozoa Crinozoa is a subphylum of mostly sessile echinoderms, of which the crinoids, or sea lilies, are the only extant members. Crinozoans have an extremely extensive fossil history, which may or may not extend into the Precambrian (provided the enigma ...

Class Crinoidea Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which ar ...

Class Paracrinoid Paracrinoidea is an extinct class of blastozoan echinoderms. They lived in shallow seas during the Early Ordovician through the Early Silurian. While blastozoans are usually characterized by types of respiratory structures present, it is not cle ...ea †

Class Cystoidea Cystoidea is a class of extinct crinozoan echinoderms, termed cystoids, that lived attached to the sea floor by stalks. They existed during the Paleozoic Era, in the Middle Ordovician and Silurian Periods, until their extinction in the Devo ... †

Class Edrioasteroidea Edrioasteroidea is an extinct class of echinoderms. The living animal would have resembled a pentamerously symmetrical disc or cushion. They were obligate encrusters and attached themselves to inorganic or biologic hard substrates (frequently h ... †

Subphylum Asterozoa The Asterozoa are a subphylum in the phylum Echinodermata. Characteristics include a star-shaped body and radially divergent axes of symmetry. The subphylum includes the class Asteroidea (the starfish), the class Ophiuroidea (the brittle stars ...

Class Ophiuroidea (Brittle star Brittle stars, serpent stars, or ophiuroids (; ; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms for locomot ...s)

Class Asteroidea (Starfish Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish a ...)

Subphylum Echinozoa

Class Echinoidea (Sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) o ...s)

Class Holothuroidea (Sea cucumber Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothuri ...s)

Class Ophiocistioidea The Ophiocistioidea is a class of extinct echinoderms from the Palaeozoic and early Mesozoic. Ophiocistioids had a flattened dome-shaped body encased in a solid test of calcareous plates, similar to that of a modern sea urchin. The mouth was at ... †

Class Helicoplacoidea Helicoplacoidea is an extinct class within the Echinodermata. All known taxa were discovered in sediments dating back to the Cambrian. †

Subphylum Blastozoa Blastozoa is a subphylum of extinct animals belonging to Phylum Echinodermata. This subphylum is characterized by the presence of specialized respiratory structures and brachiole plates used for feeding. This subphylum ranged from the Cambrian to ...

Class Blastoidea Blastoids (class Blastoidea) are an extinct type of stemmed echinoderm, often referred to as sea buds. They first appear, along with many other echinoderm classes, in the Ordovician period, and reached their greatest diversity in the Mississi ... †

Class Eocrinoidea The Eocrinoidea are an extinct class of echinoderms that lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, arm-bearing echinoderms, and were the most common echinoderms during the Cambrian. ... †

Subphylum Homostelea / Homalozoa Homalozoa is an obsolete extinct subphylum of Paleozoic era echinoderms, prehistoric marine invertebrates. They are also referred to as carpoids. Description The Homalozoa lacked the typical pentamer body form of other echinoderms, but all were ... †

Class Ctenocystoidea Ctenocystoidea is an extinct clade of echinoderms, which lived during the Cambrian and Ordovician periods. Unlike other echinoderms, ctenocystoids had bilateral symmetry, or were only very slightly asymmetrical. They are believed to be one of the ... †

Class Soluta †

Class Cincta Cincta is an extinct class of echinoderms that lived only in the Middle Cambrian epoch. Homostelea is a junior synonym. The classification of cinctans is controversial, but they are probably part of the echinoderm stem group. Cinctans were sessi ... †

Class Stylophora The stylophorans are an extinct, possibly polyphyletic group allied to the Paleozoic Era echinoderms, comprising the prehistoric cornutes and mitrates. It is synonymous with the subphylum Calcichordata. Their unusual appearances have led to a ... †

References

Subphylum
Crinozoa Crinozoa is a subphylum of mostly sessile echinoderms, of which the crinoids, or sea lilies, are the only extant members. Crinozoans have an extremely extensive fossil history, which may or may not extend into the Precambrian (provided the enigma ...

Class
Crinoidea Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which ar ...

Class
Paracrinoid Paracrinoidea is an extinct class of blastozoan echinoderms. They lived in shallow seas during the Early Ordovician through the Early Silurian. While blastozoans are usually characterized by types of respiratory structures present, it is not cle ...
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Class
Cystoidea Cystoidea is a class of extinct crinozoan echinoderms, termed cystoids, that lived attached to the sea floor by stalks. They existed during the Paleozoic Era, in the Middle Ordovician and Silurian Periods, until their extinction in the Devo ...
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Class
Edrioasteroidea Edrioasteroidea is an extinct class of echinoderms. The living animal would have resembled a pentamerously symmetrical disc or cushion. They were obligate encrusters and attached themselves to inorganic or biologic hard substrates (frequently h ...
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Subphylum
Asterozoa The Asterozoa are a subphylum in the phylum Echinodermata. Characteristics include a star-shaped body and radially divergent axes of symmetry. The subphylum includes the class Asteroidea (the starfish), the class Ophiuroidea (the brittle stars ...

Class Ophiuroidea (
Brittle star Brittle stars, serpent stars, or ophiuroids (; ; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms for locomot ...
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Class Asteroidea (
Starfish Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (). Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish a ...
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Class Echinoidea (
Sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) o ...
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Class Holothuroidea (
Sea cucumber Sea cucumbers are echinoderms from the class Holothuroidea (). They are marine animals with a leathery skin and an elongated body containing a single, branched gonad. Sea cucumbers are found on the sea floor worldwide. The number of holothuri ...
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Class
Ophiocistioidea The Ophiocistioidea is a class of extinct echinoderms from the Palaeozoic and early Mesozoic. Ophiocistioids had a flattened dome-shaped body encased in a solid test of calcareous plates, similar to that of a modern sea urchin. The mouth was at ...
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Class
Helicoplacoidea Helicoplacoidea is an extinct class within the Echinodermata. All known taxa were discovered in sediments dating back to the Cambrian.
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Subphylum
Blastozoa Blastozoa is a subphylum of extinct animals belonging to Phylum Echinodermata. This subphylum is characterized by the presence of specialized respiratory structures and brachiole plates used for feeding. This subphylum ranged from the Cambrian to ...

Class
Blastoidea Blastoids (class Blastoidea) are an extinct type of stemmed echinoderm, often referred to as sea buds. They first appear, along with many other echinoderm classes, in the Ordovician period, and reached their greatest diversity in the Mississi ...
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Class
Eocrinoidea The Eocrinoidea are an extinct class of echinoderms that lived between the Early Cambrian and Late Silurian periods. They are the earliest known group of stalked, arm-bearing echinoderms, and were the most common echinoderms during the Cambrian. ...
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Subphylum Homostelea /
Homalozoa Homalozoa is an obsolete extinct subphylum of Paleozoic era echinoderms, prehistoric marine invertebrates. They are also referred to as carpoids. Description The Homalozoa lacked the typical pentamer body form of other echinoderms, but all were ...
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Class
Ctenocystoidea Ctenocystoidea is an extinct clade of echinoderms, which lived during the Cambrian and Ordovician periods. Unlike other echinoderms, ctenocystoids had bilateral symmetry, or were only very slightly asymmetrical. They are believed to be one of the ...
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Class
Cincta Cincta is an extinct class of echinoderms that lived only in the Middle Cambrian epoch. Homostelea is a junior synonym. The classification of cinctans is controversial, but they are probably part of the echinoderm stem group. Cinctans were sessi ...
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Class
Stylophora The stylophorans are an extinct, possibly polyphyletic group allied to the Paleozoic Era echinoderms, comprising the prehistoric cornutes and mitrates. It is synonymous with the subphylum Calcichordata. Their unusual appearances have led to a ...
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