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 Paracrinoidea †
No orders, 13 to 15 genera are known.
order Comarocystitida †
?Family Heckeritidae †
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 †
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
Class Asteroidea (Starfish)
Infraclass Concentricycloidea
Superorder Forcipulatacea
Superorder Spinulosacea
Superorder Valvatacea
Notomyotida
Paxillosida
Valvatida
Velatida
† Calliasterellidae
† Trichasteropsida
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)
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 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 †
Class Soluta †
Class Cincta †
Class Stylophora †
order Cornuta †
order Mitrata †
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