Brittle star

Brittle star Temporal range: 488–0 Ma PreꞒ Ꞓ O S D C P T J K Pg N Ordovician to Present
Common brittlestar (Ophiura ophiura)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Echinodermata
Subphylum:	Asterozoa
Class:	Ophiuroidea Gray, 1840
Type species
Ophiura ophiura Linnaeus, 1758
Reorganized orders
Subclass Myophiuroidea Matsumoto, 1915 Superorder Euryophiurida O'Hara, Hugall, Thuy, Stöhr & Martynov, 2017 Euryalida Lamarck, 1816 Ophiurida Müller & Troschel, 1840 sensu O'Hara et al., 2017 Superorder Ophintegrida O'Hara, Hugall, Thuy, Stöhr & Martynov, 2017 Amphilepidida O'Hara, Hugall, Thuy, Stöhr & Martynov, 2017 Ophiacanthida O'Hara, Hugall, Thuy, Stöhr & Martynov, 2017 Ophioleucida O'Hara, Hugall, Thuy, Stöhr & Martynov, 2017 Ophioscolecida O'Hara, Hugall, Thuy, Stöhr & Martynov, 2017

Brittle stars, serpent stars, or ophiuroids (from Latin ophiurus 'brittle star'; from Ancient Greek ὄφις (óphis) 'serpent', and οὐρά (ourá) 'tail'; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms for locomotion. The ophiuroids generally have five long, slender, whip-like arms which may reach up to 60 cm (24 in) in length on the largest specimens.

The Ophiuroidea contain two large clades, Ophiurida (brittle stars) and Euryalida (basket stars). Over 2,000 species of brittle stars live today.^[1] More than 1,200 of these species are found in deep waters, greater than 200 m deep.^[1]