List of echinoderm orders explained

This List of echinoderm orders concerns the various classes and orders into which taxonomists categorize the roughly 7000 extant species^[1] as well as the extinct species of the exclusively marine phylum Echinodermata.

• 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 †
    • 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

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

Class Edrioasteroidea †

• order Edrioasterida
• order Isorophida

Class Ophiuroidea (Brittle stars)

See also: List of prehistoric 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^[2]
  • † Calliasterellidae † Trichasteropsida

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)

See also: List of prehistoric 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

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 †

References

1. Web site: Animal Diversity Web - Echinodermata. University of Michigan Museum of Zoology. 26 August 2012.
2. Web site: Asterozoa: Fossil groups: SciComms 05-06: Earth Sciences . 2008-05-07 . University of Bristol . Sweet . Elizabeth . 2005-11-22 . https://web.archive.org/web/20070714073619/http://palaeo.gly.bris.ac.uk/Palaeofiles/Fossilgroups/asteroz2/index_f/mod_fm.html . 2007-07-14 . dead .