| Ophiura ophiura | |
|---|---|
 | |
| Arm partly regenerated | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Ophiuroidea |
| Order: | Ophiurida |
| Family: | Ophiuridae |
| Genus: | Ophiura |
| Species: | O. ophiura |
| Binomial name | |
| Ophiura ophiura | |
| Synonyms | |
Ophiura ophiura or the serpent star is a species of brittle star in the order Ophiurida. It is typically found on coastal seabeds around northwestern Europe. [1]
Ophiura ophiura has a circular central disc up to 35 mm (1.5 in) wide and five radially arranged, narrow arms each up to 140 mm (6 in) long. The general colour is mottled reddish-brown with a paler underside. Both the top and the underside of the disc are covered with calcareous plates. The arms are joined to the top rather than the edge of the disc and further small, articulating plates allow the arms to bend from side to side. Small spines on the arms lie flat against the surface. Four larger plates occur across the root of each arm with the outer pair having a comb-like edge, with 20 to 30 fine papillae in each. [2] A pair of pores is seen between the underside plates at the root of the arms. [3] [4] Five large mouth-shield plates are on the underside of the disc which surround the central mouth. The teeth are in a vertical row above each of the five jaws and about five mouth papillae are on each side of the jaw. [5]
Ophiura ophiura is found on the sea floor in the northeast Atlantic Ocean and the North Sea from Norway and Sweden south to Madeira and the Mediterranean Sea. It is found below low-tide mark in the neritic zone down about 200 m, on sandy bottoms. It shows a preference for sediments with a fine grain size and about 35% mud content. [1] [5] It is a common species with 20 to 50 individuals occurring per square metre in some years in the North Sea. [6]
Ophiura ophiura is an active brittle star, moving with a jerky swimming action of its legs and sometimes burrowing. [2] It is a filter feeder, feeding on a wide range of food, [1] but also a bottom-feeding carnivore and detritivore. [7] It can regenerate its arms if they are damaged or torn off. [7]
Sexual reproduction takes place during the summer. The larvae are the typical ophiopluteus larvae of brittle stars and later settle on the sea bed and develop into juveniles. [1]
The copepod, Parartotrogus richardi, is an ectoparasite of O. ophiura. [1]
In the Clyde sea fishery for scampi ( Nephrops norvegicus ) in Scotland, the unwanted invertebrates that get caught up in the trawl include O. ophiura, as well as the starfish Asterias rubens . A study undertaken to discover the survival rate of these animals when discarded and returned to the water found that uninjured A. rubens had a mortality rate of 4%, whereas virtually all the O. ophiura died within 14 days, even when they were returned to the sea immediately after being caught. [8]
Another study examined the rate at which the discarded invertebrates sank to the bottom and their ultimate fates. O. ophiura sank relatively slowly and was preyed upon by seabirds, and the arms were eaten by fish. On the sea bed, a succession of benthic scavengers thrived on their remains with crangonid shrimps and crabs such as Carcinus maenas and Liocarcinus depurator being prominent. In six hours, little remained except the limbs of crustaceans and the discs of ophiuroids. The crab Pagurus bernhardus was the most likely scavenger to consume O. ophiura in baited traps. [9]
An echinoderm is any member of the phylum Echinodermata. The adults are recognisable by their radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest entirely marine phylum. The first definitive echinoderms appeared near the start of the Cambrian.
Brittle stars, serpent stars, or ophiuroids 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.
Discards are the portion of a catch of fish which is not retained on board during commercial fishing operations and is returned, often dead or dying, to the sea. The practice of discarding is driven by economic and political factors; fish which are discarded are often unmarketable species, individuals which are below minimum landing sizes and catches of species which fishermen are not allowed to land, for instance due to quota restrictions. Discards form part of the bycatch of a fishing operation, although bycatch includes marketable species caught unintentionally. Discarding can be highly variable in time and space as a consequence of changing economic, sociological, environmental and biological factors.
Ophiocanops fugiens is a living species in the brittle star family Ophiocanopidae. Though once considered to be the only one living species in this brittle star family, recent research has brought to light three specimens of Ophiocanops that differ substantially from O. fugiens. It has been regarded as the most primitive brittle star, close to Paleozoic forms, though other authors have disagreed with the view. Classification of O. fugiens is highly argued. Ophiocanops is usually placed in the order Oegophiurida or regarded as a genus incertae sedis or even given its own subclass Oegophiuridea. Some recent data suggest its relationship to the extant family Ophiomyxidae.
Ophiuridae are a large family of brittle stars of the suborder Ophiurina.
The common sunstar is a species of sea star belonging to the family Solasteridae. It is found in the northern parts of both the Atlantic and the Pacific Oceans.
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. It is also found along the coast of South Africa where it is known as the hairy brittle star.
Luidia ciliaris, the seven-armed sea star, is a species of sea star (starfish) in the family Luidiidae. It is found in the eastern Atlantic Ocean and the Mediterranean Sea.
Ophiocomina nigra, commonly known as the black brittle star or black serpent star, is a species of marine invertebrate in the order Ophiurida. It occurs in the north-eastern Atlantic Ocean, the North Sea, and the Mediterranean Sea.
Luidia clathrata is a tropical species of starfish in the family Luidiidae. It is variously known as the slender-armed starfish, the gray sea star, or the lined sea star. It is found in the western Atlantic Ocean.
Asterias forbesi, commonly known as Forbes sea star, is a species of starfish in the family Asteriidae. It is found in shallow waters in the northwest Atlantic Ocean and the Caribbean Sea.
Luidia senegalensis, the nine-armed sea star, is a tropical species of starfish in the family Luidiidae found in the western Atlantic Ocean.
Ophiura albida is a species of brittle star in the order Ophiurida. It is typically found on the seabed in the north eastern Atlantic Ocean and in the Mediterranean Sea and is sometimes known as the serpent's table brittle star.
Amphipholis squamata, common names brooding snake star and dwarf brittle star, is a species complex of brittle stars in the family Amphiuridae.
Ophiactis savignyi is a species of brittle star in the family Ophiactidae, commonly known as Savigny's brittle star or the little brittle star. It occurs in the tropical and subtropical parts of all the world's oceans and is thought to be the brittle star with the most widespread distribution. It was first described by the German zoologists Johannes Peter Müller and Franz Hermann Troschel in 1842. The specific name honours the French zoologist Marie Jules César Savigny.
Ophiopholis aculeata, the crevice brittle star or daisy brittle star, is a species of brittle star in the family Ophiactidae. It has a circum-polar distribution and is found in the Arctic Ocean, the northern Atlantic Ocean and the northern Pacific.
Acrocnida brachiata, the sand burrowing brittlestar, is a species of brittle star in the family Amphiuridae. It occurs on the seabed in the northeastern Atlantic Ocean and the North Sea, living semi-buried in the sand with only its arm tips projecting.
Echinocyamus pusillus, commonly known as the pea urchin or green urchin, is a species of sand dollar, a sea urchin in the family Fibulariidae, native to the northeastern Atlantic Ocean and the Mediterranean Sea. It buries itself in gravel or coarse sand at depths down to about 1,250 m (4,000 ft).
Ophiothela mirabilis is a species of ophiuroid brittle stars within the family Ophiotrichidae. O. mirabilis is an epizoic species which have a non-parasitic relationship with host sponges or gorgonians. Although native to the Pacific Ocean, it has invaded the Caribbean and southwestern Atlantic since late 2000. Many of its characteristics, including reproduction and diet, allow O. mirabilis opportunities to quickly propagate and spread through habitats.