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Ophiuroid
Brittle stars, serpent stars, or ophiuroids (; ; 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 for locomotion. The ophiuroids generally have five long, slender, whip-like arms which may reach up to in length on the largest specimens. The Ophiuroidea contain two large clades, Ophiurida (brittle stars) and Euryalida (basket stars). Over 2,000 species of brittle stars live today. More than 1,200 of these species are found in deep waters, greater than 200 m deep. Range The ophiuroids diverged in the Early Ordovician, about 500 million years ago. Ophiuroids can be found today in all of the major marine provinces, from the poles to the tropics. Basket stars are usually confined to the deeper parts of this range; Ophiuroids are known even from abyssal (>6,000 m) depths. However, brittle stars are also common members of reef communities, where the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinoderm
An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) 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. The echinoderms are important both ecologically and geologically. Ecologically, there are few other groupings so abundant in the biotic desert of the deep sea, as well as shallower oceans. Most echinoderms are able to reproduce asexually and regenerate tissue, organs, and limbs; in some cases, they can undergo complete regeneration from a single limb. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophiurida
The Ophiurida are an order of echinoderms within the class Ophiuroidea. It includes the vast majority of living brittle stars. Characteristics Ophiurida have bursae for respiration and excretion, and dorsal and ventral arm shields are present and usually well developed. Arms are unbranched and incapable of coiling vertically. Most are five-armed, some with 4 or 6 arms as an abnormality, but others properly bear six or seven arms. The madreporite is on the oral surface. The digestive glands are entirely within the central disc. They move their arms side to side by means of ball-and-socket joints. Tropical species tend to contrast color from the environment, but most others prefer to blend in. These biochromes do not include echinochromes. Systematics and phylogeny There is currently no consensus as to the subdivision of the Ophiurida. The order has been divided into the following suborders and infraorders * Ophiomyxina * Ophiurina ** Hemieuryalina ** Chilophiurina ** Gna ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asteroidea
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 live on the seabed in all the world's oceans, from warm, tropical zones to frigid, polar regions. They are found from the intertidal zone down to abyssal depths, at below the surface. Starfish are marine invertebrates. They typically have a central disc and usually five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates. Many species are brightly coloured in various shades of red or orange, while others are blue, grey or brown. Starfish have tube feet operated by a hydraulic system and a mouth at the centre of the oral or lower surface. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Starfish
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 live on the seabed in all the world's oceans, from warm, tropical zones to frigid, polar regions. They are found from the intertidal zone down to abyssal depths, at below the surface. Starfish are marine invertebrates. They typically have a central disc and usually five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth, granular or spiny, and is covered with overlapping plates. Many species are brightly coloured in various shades of red or orange, while others are blue, grey or brown. Starfish have tube feet operated by a hydraulic system and a mouth at the centre of the oral or lower surface. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Water Vascular System
The water vascular system is a hydraulic system used by echinoderms, such as sea stars and sea urchins, for locomotion, food and waste transportation, and respiration. The system is composed of canals connecting numerous tube feet. Echinoderms move by alternately contracting muscles that force water into the tube feet, causing them to extend and push against the ground, then relaxing to allow the feet to retract. The exact structure of the system varies somewhat between the five classes of echinoderm. The system is part of the coelomic cavities of echinoderms, together with the haemal coelom (or haemal system), perivisceral coelom, gonadal coelom and perihaemal coelom. Other terms sometimes used to refer to the water vascular system are "ambulacral system" and "aquiferous system". In the past, "aquiferous system" was also used to refer to many unrelated invertebrate structures, but today, it is restricted to water channels in sponges and the hydrostatic skeleton of some mollusks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Euryalida
The Euryalida are an order of brittle stars, which includes large species with either branching arms (called "basket stars") or long and curling arms (called "snake stars"). Characteristics Many of the species in this order have characteristic repeatedly branched arms (a shape known as "basket stars", which includes most Gorgonocephalidae and two species in the family Euryalidae), while the other species have very long and curling arms, and go rather by the name of "snake stars" (mostly abyssal species). Many of them live in deep sea habitats or cold waters, though some basket stars can be seen at night in shallow tropical reefs. Most young basket stars live on specific type of coral. In the wild they may live up to 35 years. They weigh up to Like other echinoderms, basket stars lack blood and achieve gas exchange via their water vascular system. The basket stars are the largest ophiuroids with '' Gorgonocephalus stimpsoni'' measuring up to 70 cm in arm length wit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophiacanthida
Ophiacanthida is an order of echinoderms belonging to the class Ophiuroidea. Families: * Ophiodermatina Ljungman, 1867 ** Ophiodermatidae ** Ophiomyxidae ** Ophiopezidae ** Ophiocomidae Ophiocomidae are a family of brittle stars of the suborder Ophiurina. Systematics and phylogeny Ophiocomidae has been placed (along with Ophionereididae) to the superfamily Ophiocomidea and infraorder Order ( la, ordo) is one of the eigh ... * Ophiacanthina O'Hara, Hugall, Thuy, Stöhr & Martynov, 2017 ** Clarkcomidae ** Ophiacanthidae ** Ophiobyrsidae ** Ophiocamacidae ** Ophiopteridae ** Ophiotomidae ** Ophiojuridae References Ophiuroidea Echinoderm orders {{Ophiuroidea-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphilepidida
Amphilepidida is an order of echinoderms belonging to the class Ophiuroidea Brittle stars, serpent stars, or ophiuroids (; ; 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 for locomot .... Families: * Amphilepididae * Amphilimnidae * Amphiuridae * Hemieuryalidae * Ophiactidae * Ophiolepididae * Ophionereididae * Ophiopholidae * Ophiopsilidae * Ophiothamnidae * Ophiotrichidae References Ophiuroidea Echinoderm orders {{ophiuroidea-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophioscolecida
Ophioscolecida is an order of echinoderms belonging to the class Ophiuroidea Brittle stars, serpent stars, or ophiuroids (; ; 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 for locomot .... Families: * Ophiohelidae * Ophioscolecidae References Ophiuroidea Echinoderm orders {{ophiuroidea-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Madreporite
The madreporite is a light colored calcareous opening used to filter water into the water vascular system of echinoderms. It acts like a pressure-equalizing valve. It is visible as a small red or yellow button-like structure, looking like a small wart, on the aboral surface of the central disk of a sea star or sea urchin or the oral surface of Ophiuroidea. Close up, it is visibly structured, resembling a "madrepore" (stone coral, Scleractinia) colony. From this, it derives its name. The water vascular system of the sea star consists of a series of seawater-filled ducts that function in locomotion and feeding and respiration. Its main parts are the madreporite, the stone canal, the ring canal, the radial canals, the lateral canals, and the tube feet. The sieve-like madreporite allows entry of seawater into the stone canal, which connects to the ring canal around the mouth. Five or more radial canals extend from the ring canal, one in each arm above the ambulacral groove. From th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophiopetra Lithographica Aboral Larger 010813
''Ophiopetra'' is a genus of prehistoric brittle stars. It lived in lagoons A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') an ... in Solnhofen Plattenkalk Formation. It has only one known species, ''Ophiopetra lithographica''. Taxonomic history Both ''Ophiopetra'' and ''O. lithographica'' were first described by Raymond Enay and Hans Hess in 1962, who determined that the genus belonged to the order Chilophiurida Matsumoto, 1915 (later known as the infraorder Chilophiurina) and that it was related to the families Ophiodermatidae and Ophiochitonidae. In 1965, Hess then showed that the genus '' Aplocoma'' d'Orbigny, 1852 was related to ''Ophiopetra'', and proposed a new family, Aplocomidae Hess, 1965, for the two genera. In 2008, ''Ophiopetra'' and another genus, ''Ophiohybris'' He ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brackish Water
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root '' brak''. Certain human activities can produce brackish water, in particular civil engineering projects such as dikes and the flooding of coastal marshland to produce brackish water pools for freshwater prawn farming. Brackish water is also the primary waste product of the salinity gradient power process. Because brackish water is hostile to the growth of most terrestrial plant species, without appropriate management it is damaging to the environment (see article on shrimp farms). Technically, brackish water contains between 0.5 and 30 grams of salt per litre—more often expressed as 0.5 to 30 parts per thousand (‰), which is a specific gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
