Ophiothrix fragilis is a species of brittle star in the orderOphiurida. It is found around the coasts of western Europe and is known in Britain as the common brittle star.[3][4] It is also found along the coast of South Africa where it is known as the hairy brittle star.[5][6]
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. The central disc is about one centimetre in diameter with the five arms being about five times as long. The disc is clothed in five rays of spines radiating from a spiny centre. Between these are five pairs of triangular plates, each pair forming a heart shaped pattern. The slender tapering arms are quite distinct from the disc and are covered with overlapping scales.[7] The dorsal arm plates are naked and have a longitudinal keel.[8] Each arm segment bears seven glassy, toothed spines. The arms are extremely fragile and easily shed, coming away either whole or in pieces.[7]
Distribution and habitatedit
This species is common around the coasts of Britain and Ireland and in the North Sea. It ranges southwards from the Lofoten Islands and Iceland to the Mediterranean Sea and the Azores, and along the west coast of Africa south to the Cape of Good Hope.[8] It is most common on tide-swept rock and on coarse sediments,[9] preferring hard substrates including sand and shingle. It is often found in empty shells or under stones, from the littoral zone down to 350 metres.[8]
Biologyedit
Ophiothrix fragilis
The common brittle star sometimes congregates offshore in vast numbers and as many as two thousand individuals have been recorded in a single square metre.[10] Higher up the shore it normally lives a solitary existence under seaweed or pebbles or in crevices.[11] It moves by jerking a pair of limbs forward and pulling itself along.[7]
The common brittle star is a scavenger, feeding on dead organisms. It is also a suspension feeder, raising an arm and extending the tube feet in order to catch particles floating by.[12] It then passes the food to the mouth with its arms.[13] Its abundance varies according to environmental conditions including temperature and the availability of food. After mild winters, it has been found in very large numbers in the Oosterschelde estuary in the Netherlands.[14]
The common brittle star is itself eaten by other species and can be found among the stomach contents of most common predators.[15] However its glassy spicules may make it unpalatable, it lives in concealed places and is well camouflaged so that it blends in with its surroundings which combine to reduce predation. A study of skeletal bands suggests that it may live for as many as ten years.[9]
Like some other brittle stars, Ophiothrix fragilis has symbioticbacteria under its cuticle. The host-bacteria association can be upset by acute stress, and changes in levels of bacteria present can be used as an indicator of stress.[16]
This brittle star usually spawns between May and January. Each individual is thought to spawn just once during each breeding season. A week after spawning, the planktonic larvae appear in the water column. They metamorphose into young brittle stars which drift in the plankton for about three weeks before settling. The smallest brittle stars found have just two segments per arm and a disc diameter of two millimetres.[9]
^Branch, G.M.; Branch, M.L.; Griffiths, C.L.; Beckley, L.E. (2010). Two Oceans: a guide to the marine life of southern Africa (2nd ed.). Cape Town: Struik Nature. ISBN978 1 77007 772 0.
^Jones, Georgina (2008). A field guide to the marine animals of the Cape Peninsula. Cape Town: SURG. ISBN978-0-620-41639-9.
^ abcJohn Barrett and C M Young, Collins Pocket Guide to the Sea Shore (1958) p.180
^ abc. Archived from the original on 2012-04-02. Retrieved 2011-06-18.
^Davoult, D., (1989). Demographic structure and production of the Ophiothrix fragilis population in the Dover Strait (French part). Proceedings of the 6th international symposium on Echinodermata. Echinoderms: living and fossils. Ile des Embiez (Var. France) 19–22 September 1988. Vie Marine. Hors Series,10, 116-127.
^Warner, G.F. & Woodley, J.D., (1975). Suspension feeding in the brittle star Ophiothrix fragilis. Journal of the Marine Biological Association of the United Kingdom, 55, 199-210.
^Fish, J.D. and Fish, S. (1996) A student's guide to the seashore. Second Edition. Cambridge University Press, Cambridge.
^Smaal, A.C., (1994). Theme V: The response of benthic suspension feeders to environmental changes. The Oosterschelde Estuary (The Netherlands): A case study of a changing ecosystem. Hydrobiologia, 282-283, 355-357.
^Warner, G.F., (1971). On the ecology of a dense bed of the brittle star Ophiothrix fragilis. Journal of the Marine Biological Association of the United Kingdom, 51, 267-282.
^Newton, L.C. & McKenzie, J.D., (1995). Echinoderms and oil pollution: a potential stress assay using bacterial symbionts. Marine Pollution Bulletin, 31, 453-456.
External linksedit
Wikispecies has information related to Ophiothrix fragilis.
Photos of Ophiothrix fragilis on Sealife Collection
January 01, 1970
ophiothrix, fragilis, species, brittle, star, order, ophiurida, found, around, coasts, western, europe, known, britain, common, brittle, star, also, found, along, coast, south, africa, where, known, hairy, brittle, star, scientific, classification, domain, euk. Ophiothrix fragilis is a species of brittle star in the order Ophiurida It is found around the coasts of western Europe and is known in Britain as the common brittle star 3 4 It is also found along the coast of South Africa where it is known as the hairy brittle star 5 6 Ophiothrix fragilis Ophiothrix fragilis Scientific classification Domain Eukaryota Kingdom Animalia Phylum Echinodermata Class Ophiuroidea Order Ophiurida Family Ophiotrichidae Genus Ophiothrix Species O fragilis Binomial name Ophiothrix fragilisAbildgaard 1789 1 Synonyms Asteria cuvieri Delle Chiaje 1828 Asteria ferrussacii Delle Chiaje 1828 Asterias echinata Delle Chiaje 1828 Asterias fragilis Abildgaard in O F Muller 1789 Asterias pentaphylla Pennant 1777 Asterias rubra Delle Chiaje 18 Ophiocoma minutaForbes 1839 Ophiocoma rosula Forbes 1839 Ophiothrix alopecurus Muller amp Troschel 1842 Ophiothrix echinata Delle Chiaje 1828 Ophiothrix ferussacii Delle Chiaje 18 Ophiothrix fragilis var abildgaardi Ophiothrix fragilis var echinata Delle Ophiothrix fragilis var lusitanica Ljungman 1872 Ophiothrix fragilis var pentaphyllum Pennant 1777 Ophiothrix lusitanica Ljungman 1872 Ophiothrix pentaphyllum Abildgaard 1789 Ophiothrix rammelsbergii Muller amp Troschel 1842 Ophiothrix rubra Ljungman 1872 Ophiothrix triglochis Muller amp Troschel 1842 2 Contents 1 Description 2 Distribution and habitat 3 Biology 4 References 5 External linksDescription edit nbsp 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 The central disc is about one centimetre in diameter with the five arms being about five times as long The disc is clothed in five rays of spines radiating from a spiny centre Between these are five pairs of triangular plates each pair forming a heart shaped pattern The slender tapering arms are quite distinct from the disc and are covered with overlapping scales 7 The dorsal arm plates are naked and have a longitudinal keel 8 Each arm segment bears seven glassy toothed spines The arms are extremely fragile and easily shed coming away either whole or in pieces 7 Distribution and habitat editThis species is common around the coasts of Britain and Ireland and in the North Sea It ranges southwards from the Lofoten Islands and Iceland to the Mediterranean Sea and the Azores and along the west coast of Africa south to the Cape of Good Hope 8 It is most common on tide swept rock and on coarse sediments 9 preferring hard substrates including sand and shingle It is often found in empty shells or under stones from the littoral zone down to 350 metres 8 Biology edit nbsp Ophiothrix fragilis The common brittle star sometimes congregates offshore in vast numbers and as many as two thousand individuals have been recorded in a single square metre 10 Higher up the shore it normally lives a solitary existence under seaweed or pebbles or in crevices 11 It moves by jerking a pair of limbs forward and pulling itself along 7 The common brittle star is a scavenger feeding on dead organisms It is also a suspension feeder raising an arm and extending the tube feet in order to catch particles floating by 12 It then passes the food to the mouth with its arms 13 Its abundance varies according to environmental conditions including temperature and the availability of food After mild winters it has been found in very large numbers in the Oosterschelde estuary in the Netherlands 14 The common brittle star is itself eaten by other species and can be found among the stomach contents of most common predators 15 However its glassy spicules may make it unpalatable it lives in concealed places and is well camouflaged so that it blends in with its surroundings which combine to reduce predation A study of skeletal bands suggests that it may live for as many as ten years 9 Like some other brittle stars Ophiothrix fragilis has symbiotic bacteria under its cuticle The host bacteria association can be upset by acute stress and changes in levels of bacteria present can be used as an indicator of stress 16 This brittle star usually spawns between May and January Each individual is thought to spawn just once during each breeding season A week after spawning the planktonic larvae appear in the water column They metamorphose into young brittle stars which drift in the plankton for about three weeks before settling The smallest brittle stars found have just two segments per arm and a disc diameter of two millimetres 9 References edit Encyclopedia of Life World Register of Marine Species Common Brittle Star British Sea Fishing Retrieved 15 March 2023 Common brittlestar The Wildlife Trusts Retrieved 15 March 2023 Branch G M Branch M L Griffiths C L Beckley L E 2010 Two Oceans a guide to the marine life of southern Africa 2nd ed Cape Town Struik Nature ISBN 978 1 77007 772 0 Jones Georgina 2008 A field guide to the marine animals of the Cape Peninsula Cape Town SURG ISBN 978 0 620 41639 9 a b c John Barrett and C M Young Collins Pocket Guide to the Sea Shore 1958 p 180 a b c Marine Species Identification Portal a b c MarLIN Archived from the original on 2012 04 02 Retrieved 2011 06 18 Davoult D 1989 Demographic structure and production of the Ophiothrix fragilis population in the Dover Strait French part Proceedings of the 6th international symposium on Echinodermata Echinoderms living and fossils Ile des Embiez Var France 19 22 September 1988 Vie Marine Hors Series 10 116 127 Ulster Museum Warner G F amp Woodley J D 1975 Suspension feeding in the brittle star Ophiothrix fragilis Journal of the Marine Biological Association of the United Kingdom 55 199 210 Fish J D and Fish S 1996 A student s guide to the seashore Second Edition Cambridge University Press Cambridge Smaal A C 1994 Theme V The response of benthic suspension feeders to environmental changes The Oosterschelde Estuary The Netherlands A case study of a changing ecosystem Hydrobiologia 282 283 355 357 Warner G F 1971 On the ecology of a dense bed of the brittle star Ophiothrix fragilis Journal of the Marine Biological Association of the United Kingdom 51 267 282 Newton L C amp McKenzie J D 1995 Echinoderms and oil pollution a potential stress assay using bacterial symbionts Marine Pollution Bulletin 31 453 456 External links edit nbsp Wikispecies has information related to Ophiothrix fragilis ARKive video showing O fragilis feeding Photos of Ophiothrix fragilis on Sealife Collection Retrieved from https en wikipedia org w index php title Ophiothrix fragilis amp oldid 1187046066, wikipedia, wiki, book, books, library,
