| Ophiopholis aculeata | |
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| Species: | O. aculeata |
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| Ophiopholis aculeata | |
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Ophiopholis aculeata, the crevice brittle star [2] or daisy brittle star, [3] 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.
Ophiopholis aculeata has a central pentagonal disc up to 2 cm (0.8 in) in diameter; this is clearly set off from the five robust, twisted arms, which are four times as long as the disc is wide. The mouth is on the oral or underside of the disc and is surrounded by five toothed jaws. The aboral or upper side of the disc is granular, and a pair of large scales, the radial shield, covers the base of each arm. The radial shield is covered with small spines which conceal the scales. The many-jointed arms are covered with more scales both on the oral and aboral surfaces; on the aboral surface there is a regular series of oval scales each surrounded by smaller scales. There are six or seven stout spines per segment, with one short spine being hooked. The colour varies, being often reddish or variegated, and sometimes purplish; the central scales on the disc often form a ten-pointed star and there are often darker bands on the arms. [2] [4]
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] It is generally found on rocky substrates where it has a tendency to hide inside shells, in hollows and crevices. It generally occurs at depths less than 300 m (1,000 ft) but has been found as deep as 1,880 m (6,200 ft). [2]
Ophiopholis aculeata feeds on detritus and small organisms that it traps with its tube feet and with mucus secreted by glands on its arms. It is preyed on by fish and birds. [5]
The sexes are separate in this species, and fertilisation is external. Mass spawning events have been seen, with all the individuals of this species in a locality releasing their spawn at the same time in response to some environmental cue. [6] This has been observed in Jamaica at night, during the period 20:00 hours to 22:00 hours, and in both morning and afternoon in the Gulf of Saint Lawrence, Canada. The cue that triggers a spawning event may be a change in the temperature of the water. Spawning tends to occur at 6.5 to 7 °C (43.7 to 44.6 °F) in Alaska, and about a degree cooler than this further north in the White Sea. Several spawning events have occurred when warmer surface waters have down-welled into deep, colder water layers. [6] The larvae of brittle stars are known as ophiopluteus larvae and form part of the plankton. When they are fully developed, they settle on the seabed and undergo metamorphosis into juvenile brittle stars. [7]
An echinoderm is any member of the phylum Echinodermata of marine animals. The adults are recognizable by their radial symmetry, and include starfish, 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 7000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest phylum that has no freshwater or terrestrial members.
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea. Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish are also known as Asteroids due to being in the class Asteroidea. About 1,900 species of starfish occur on the seabed in all the world's oceans, from the tropics to frigid polar waters. They are found from the intertidal zone down to abyssal depths, 6,000 m (20,000 ft) below the surface.
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. From New Latin ophiurus, from Ancient Greek ὄφις + οὐρά.
Ophiopholis is a genus of brittle stars (Ophiuroidea) found in oceans worldwide from tropics to temperate regions.
Ceramaster patagonicus, the cookie star, is a species of sea star. It is bright orange or yellow in colour. Its arms are short and it has no spines. It is a deep water species and lives on rocky sea beds. Its diet includes sponges.
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.
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.
The purple sunstar, northern sunstar, or smooth sun star, Solaster endeca, is a species of starfish in the family Solasteridae.
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.
Ophiocoma scolopendrina is a species of brittle star belonging to the family Ophiocomidae. Restricted to life in the intertidal, they live in the Indo-Pacific. They can typically be found within crevices or beneath borders on intertidal reef platforms. Unlike other Ophiocoma brittle stars, they are known for their unique way of surface-film feeding, using their arms to sweep the sea surface and trap food. Regeneration of their arms are a vital component of their physiology, allowing them to efficiently surface-film feed. These stars also have the ability to reproduce throughout the year, and have been known to have symbiotic relationships with other organisms.
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.
Ophionereis reticulata, the reticulated brittle star, is a brittle star in the family Ophionereididae. It is found in shallow parts of the western Atlantic, Caribbean Sea and Gulf of Mexico.
Amphiura filiformis is a species of brittle star belonging to the family Amphiuridae. It is found on the seabed in the north east Atlantic Ocean and adjoining seas to a depth of 200 metres (660 ft). It digs itself a shallow burrow in the sand and waves its arms in the water above to suspension feed on plankton.
Amphiura chiajei is a species of brittle star belonging to the family Amphiuridae. It is found in the northeastern Atlantic Ocean and adjoining seas to a depth of 1,000 metres (3,300 ft). It digs itself into the soft sediment of the seabed and raises its arms into the water above to suspension feed on plankton. It was first described by the British naturalist Edward Forbes in 1843, and was named for the Italian zoologist Stefano Delle Chiaje (1794–1860).
Ophiocoma echinata, the spiny ophiocoma, is a species of brittle star belonging to the family Ophiocomidae. It is the type species of the genus Ophiocoma and is found in the tropical west Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico.
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.
Ophiothrix angulata, the angular brittle star, is a species of marine invertebrate in the order Ophiurida. It is found in the warm waters of the western Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico.
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.
Amphiodia urtica, commonly known as the burrowing brittle star or the long arm brittle star, is a species of brittle star belonging to the family Amphiuridae. It is found on the Pacific coast of North America at depths down to about 370 m (1,200 ft).
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).