List of echinoderm orders

A brittle star, Ophionereis reticulata

A sea cucumber from Malaysia

Starfish exhibit a wide range of colours

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

Crinoid

• 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)

Haeckel Cystoidea

Class Paracrinoidea †

No orders, 13 to 15 genera are known.

Class Cystoidea †

• order Aristocystitida †
• order Asteroblastida †
• order Glyptosphaeritida †
• order Sphaeronitida †

Class Edrioasteroidea †

Streptaster vorticellatus (Edrioasteroidea)

• order Edrioasterida
• order Isorophida

Subphylum Asterozoa

Class Ophiuroidea (Brittle stars)

See also: List of prehistoric 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)

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)

Strongylocentrotus purpuratus, a well-armoured sea urchin

• • 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)

See also: List of prehistoric 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 †

Ophiocystioidea

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 Helioplacoidea †

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

Subphylum Blastozoa †

Class Blastoidea †

Blastoidea

• Ordre Coronata †
• Order Fissiculata †
• Order Spiraculata †
• basal Macurdablastus †

Class Eocrinoidea †

Gogia spiralis (Eocrinoidea)

• Order Ascocystida †
• Order Gogiida †
• Order Imbricata †
• Order Trachelocrinida †

Subphylum Homostelea / Homalozoa †

Corthurnocystis, a Stylophora.

Class Ctenocystoidea †

• • order Ctenocystida †

Class Homoiostelea †

• • order Soluta †

Class Homostelea †

• • order Cincta †

= Class Stylophora †

• • order Cornuta †
  • order Mitrata †