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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 ...
Starfish are included in the subphylum Asterozoa, the characteristics of which include a flattened, star-shaped body as adults consisting of a central disc and multiple radiating arms. The subphylum includes the two classes of Asteroidea, the starfish, and Ophiuroidea, the brittle stars and basket stars.
Many brittle stars are hermaphrodites; they often brood their eggs, usually in special chambers on their oral surfaces, but sometimes in the ovary or coelom. [58] In these starfish and brittle stars, development is usually direct to the adult form, without passing through a bilateral larval stage. [59]
Crinoids are echinoderms in the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. [5] They live in both shallow water [6] and in depths of over 9,000 metres (30,000 ft). [7] Adult crinoids are characterised by having the mouth located on the upper surface.
This brittle star has a circum-boreal distribution. In the northern Atlantic Ocean it is common around Iceland, Spitzbergen and Norway southwards to the North Sea.On the eastern coast of North America its range extends from Greenland southwards to Long Island, and in the Pacific Ocean, its range stretches from Japan and the Bering Sea southwards to California. [3]
Brittle stars do not have pedicellariae, and the plates that cover their surface are known as shields. On the arms these are in four rows with each segment having an aboral and oral shield and two lateral shields, usually with fringing spines. Other ossicles include spines, tubercles, small scales and vertebrae.
The common brittle star, Ophiothrix fragilis, Strangford Lough, Co. Down, Northern Ireland, -22 m, 5 September 2007. The common brittle star is extremely variable in colouration, ranging from violet, purple or red to yellowish or pale grey, often spotted with red. The arms are usually white or grey with pink bands.
Ophiothrix suensoni, Suenson's brittle star or the sponge brittle star, is a species of marine invertebrate in the order Ophiurida. It is found in the Caribbean Sea and Gulf of Mexico. It is included in the subgenus Acanthophiothrix making its full scientific name Ophiothrix (Acanthophiothrix) suensoni. [1]