# List of echinoderm orders

This List of echinoderm orders concerns the various classes and orders into which taxonomists categorize the roughly 7000 extant species as well as the extinct species of the exclusively marine phylum Echinodermata.

## Subphylum Crinozoa
### Class Crinoidea

* Subclass Articulata (540 species)
** Order Bourgueticrinida
** Order Comatulida
** Order Cyrtocrinida
** Order Hyocrinida
** Order Isocrinida
** Order Millericrinida
* Subclass †Flexibilia
* Subclass †Camerata
* Subclass †Disparida
* Comaster schlegelii (Comatulida)
* Holopus sp. (Cyrtocrinida)
* Encrinus liliiformis (Encrinida)
* Calamocrinus diomedae (Hyocrinida)
* Proisocrinus ruberrimus (Isocrinida)
* Liliocrinus polydactylus (Millericrinida)

### Class Paracrinoidea †

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

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

### Class Edrioasteroidea †

* order Edrioasterida
* order Isorophida

## Subphylum Asterozoa
### Class Ophiuroidea (Brittle stars)

* order Euryalida
* order Ophiurida
* order Amphilepidida
* order Ophiacanthida
* order Ophioleucida
* order Ophioscolecida
* Astroboa nuda (Euryalida)
* Ophiura ophiura (Ophiurida)
* Ophiolepis elegans (Amphilepidida)
* Ophiocoma erinaceus (Ophiacanthida)
* Ophioleuce seminudum (Ophioleucida)
* Ophiomyces frutectosus (Ophioscolecida)

### Class Asteroidea (Starfish)

* Infraclass Concentricycloidea
** Peripodida
* Superorder Forcipulatacea
** Brisingida
** Forcipulatida
* Superorder Spinulosacea
** Spinulosida
* Superorder Valvatacea
** Notomyotida
** Paxillosida
** Valvatida
* Velatida
* † Calliasterellidae
* † Trichasteropsida
* Xyloplax janetae (Peripodida)
* Novodinia antillensis (Brisingida)
* Pisaster ochraceus (Forcipulatida)
* Echinaster sepositus (Spinulosida)
* Cheiraster echinulatus (Notomyotida)
* Astropecten aranciacus (Paxillosida)
* Linckia laevigata (Valvatida)
* Euretaster insignis (Velatida)

## Subphylum Echinozoa
### Class Echinoidea (Sea urchins)

* Superorder Diadematacia
** Order Diadematoida
** Order Echinothurioida
** Order Pedinoida
* Superorder Echinacea
** Order Arbacioida
** Order Echinoida
** Order Phymosomatoida
** Order Salenioida
** Order Temnopleuroida
* Superorder Gnathostomata
** Order Clypeasteroida (sand dollars)
** Order Holectypoida
* Superorder Atelostomata
** Order Holasteroida
** Order Spatangoida (heart urchins)
* Aspidodiadema hawaiiense, an Aspidodiadematoida
* Diadema antillarum, a Diadematoida
* Caenopedina hawaiiensis, a Pedinoida
* Salenocidaris hastigera, a Salenioida
* Arbacia lixula, an Arbacioida
* Strongylocentrotus franciscanus, a Camarodonta
* Stomopneustes variolaris, a Stomopneustoida
* Asthenosoma marisrubri, an Echinothurioida
* Pourtalesia wandeli, a Holasteroida
* Maretia planulata, a Spatangoida
* Echinoneus cyclostomus, an Echinoneoida
* Clypeaster reticulatus, a Clypeasteroida
* Echinolampas depressa, an Echinolampadoida
* Eucidaris metularia, a Cidaroida

### Class Holothuroidea (Sea cucumbers)

* Order Apodida
* Order Dendrochirotida
* Order Elasipodida
* Order Holothuriida
* Order Molpadida
* Order Persiculida
* Order Synallactida
* Euapta godeffroyi (Apodida)
* Cercodemas anceps (Dendrochirotida)
* Scotoplanes globosa (Elasipodida)
* Holothuria cinerascens (Holothuriida)
* Paracaudina australis (Molpadida)
* Hansenothuria benti (Persiculida)
* Stichopus herrmanni (Synallactida)

### Class Ophiocistioidea †

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 †

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

## Subphylum Blastozoa
### Class Blastoidea †

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

### Class Eocrinoidea †

* Order Ascocystida †
* Order Gogiida †
* Order Imbricata †
* Order Trachelocrinida †

## Subphylum Homostelea / Homalozoa †
### Class Ctenocystoidea †

* order Ctenocystida †

### Class Stylophora †

* order Cornuta †
* order Mitrata †