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

? Class Camptostromatoidea †

Recent research has found weak support for the recovery of Camptostroma as the sister group of the crinoids. However, other phylogenies are ambiguous regarding whether it is closer to the crinoids, eocrinoids, or eleutherozoans.

Subphylum Asterozoa

Class Ophiuroidea (Brittle stars)

order Euryalida order Ophiurida order Amphilepidida order Ophiacanthida order Ophioleucida order Ophioscolecida

Class Asteroidea (Starfish) Infraclass Concentricycloidea Peripodida Superorder Forcipulatacea Brisingida Forcipulatida Superorder Spinulosacea Spinulosida Superorder Valvatacea Notomyotida Paxillosida Valvatida Velatida † Calliasterellidae † Trichasteropsida

Subphylum Echinozoa

Class Echinoidea (Sea urchins)

Superorder Diadematacea 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)

Class Holothuroidea (Sea cucumbers)

Order Apodida Order Dendrochirotida Order Elasipodida Order Holothuriida Order Molpadida Order Persiculida Order 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 Edrioasteroidea †

order Stromatocystitida order Edrioasterida order Isorophida

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 †

Class Paracrinoidea † order Comarocystitida † order Platycystitida †

Class Rhombifera † Note that Rhombiferans are often included in the informal group (and former class) Cystoidea†.

Order Dichoporita† Order Fistuliporita†

Class Diploporita † Note that Diploporitans are often included in the informal group (and former class) Cystoidea†.

order Aristocystitida order Asteroblastida order Glyptosphaeritida order Sphaeronitida

Subphylum Homalozoa †

Class Ctenocystoidea † order Ctenocystida †

Class Soluta †

Sometimes treated as Class Homoiostelea, Order Soluta

Class Cincta †

Sometimes treated as Class Homostelea, Order Cincta

Class Stylophora † order Cornuta † order Mitrata †

References

Works cited