About Ophiothrix fragilis (Abildgaard, 1789)
Ophiothrix fragilis, commonly called the common brittle star, has extremely variable coloration. Its body ranges in color from violet, purple, or red to yellowish or pale grey, and is often spotted with red. Its arms are usually white or grey with pink bands. The central disc is roughly one centimetre in diameter, and its five arms are about five times the diameter of the disc in length. The disc is covered by five rays of spines that radiate from a spiny central area. Between these spine rays are five pairs of triangular plates, with each pair forming a heart-shaped pattern. Its slender, tapering arms are clearly distinct from the disc and are covered in overlapping scales. The dorsal arm plates are hairless and bear a longitudinal keel. Each arm segment has seven glassy, toothed spines. The arms are extremely fragile and easily shed, breaking away either whole or in fragments. This species is common around the coasts of Britain and Ireland, and throughout the North Sea. Its distribution ranges southward from the Lofoten Islands and Iceland to the Mediterranean Sea and the Azores, and along the west coast of Africa as far south as the Cape of Good Hope. It is most abundant on tide-swept rock and coarse sediments, and prefers hard substrates that include sand and shingle. It is frequently found inside empty shells or under stones, and occurs from the littoral zone down to a depth of 350 metres.
