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Allantactis
''Allantactis'' is a monotypic genus of sea anemones, and ''Allantactis parasitica'' is the only species in the genus. This sea anemone lives at bathyal depths in the North Atlantic Ocean and has a symbiotic relationship with a gastropod mollusc. Description ''A. parasitica'' has a strong base and a smooth column with thick walls and no cuticle or perforations of the body wall that are termed ''cinclides''. The margin is distinct and the sphincter powerful. The tentacles are fairly short and arranged in whorls of six, there being a maximum of 96. The oral disc has a central mouth with two broad siphonoglyphs. The six pairs of mesenteries are complete, in that their sheetlike membranes join the gastrodermis of the body wall with that of the pharynx, and are sterile, in that they do not bear gonads. The nematocysts consist of a mixture of spirocysts, basitrichs and microbasic p-mastigophors. Ecology The species lives on the abyssal seabed of the North Atlantic at depths of bet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hormathiidae
Hormathiidae is a family of sea anemones in the class Anthozoa. Genera Genera in this family include: * '' Actinauge'' Verrill, 1883 * ''Adamsia'' Forbes, 1840 * ''Allantactis'' Danielssen, 1890 * '' Calliactis'' Verrill, 1869 * '' Cataphellia'' Stephenson, 1929 * '' Chitonanthus'' * '' Chondranthus'' Migot & Portmann, 1926 * '' Chondrophellia'' Carlgren, 1925 * '' Gliactis'' * '' Handactis'' Fautin, 2016 * '' Hormathia'' Gosse, 1859 * '' Hormathianthus'' Carlgren, 1943 * '' Leptoteichus'' Stephenson, 1918 * ''Monactis'' Riemann-Zurneck, 1986 * '' Paracalliactis'' Carlgren, 1928 * ''Paraphellia ''Paraphellia'' is a genus of cnidarians belonging to the family Hormathiidae. The species of this genus are found in Western Europe, Northern Africa, Malesia Malesia is a biogeographical region straddling the Equator and the boundaries of ...'' Haddon, 1889 * '' Paraphelliactis'' Carlgren, 1928 * '' Parastephanauge'' Dufaure, 1959 * '' Phelliactis'' Simon, 1892 References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daniel Cornelius Danielssen
Daniel Cornelius Danielssen (4 July 1815 – 13 July 1894) was a Norwegian physician. He was most noted for his research regarding the causes and treatment of leprosy. Biography Danielssen was from Bergen, Norway. Dating from 1839, he was associated with St. Jørgens Hospital (''Sankt Jørgens Hospital'') in Bergen. He later worked with Gerhard Armauer Hansen, discovering the bacteria causing leprosy, and made Bergen a world centre of lepra research in the middle of the nineteenth century. With dermatologist Carl Wilhelm Boeck, he was co-author of an acclaimed study on lepra titled ''Om Spedalskhed'' (1847).Daniel Cornelius Danielssen biography @ In October 1849, he was named h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gonad
A gonad, sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells. Both of these gametes are haploid cells. Some hermaphroditic animals have a type of gonad called an ovotestis. Evolution It is hard to find a common origin for gonads, but gonads most likely evolved independently several times. Regulation The gonads are controlled by luteinizing hormone and follicle-stimulating hormone, produced and secreted by gonadotropes or gonadotrophins in the anterior pituitary gland. This secretion is regulated by gonadotropin-releasing hormone produced in the hypothalamus. Development Gonads start developing as a common primordium (an organ in the earliest stage of development), in the form of genital ridges, which ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lunar Phase
Concerning the lunar month of ~29.53 days as viewed from Earth, the lunar phase or Moon phase is the shape of the Moon's directly sunlit portion, which can be expressed quantitatively using areas or angles, or described qualitatively using the terminology of the 4 major phases: new moon, first quarter, full moon, last quarter and 4 minor phases: waxing crescent, waxing gibbous, waning gibbous, and waning crescent. The lunar phases gradually change over a synodic month (~29.53 days) as the Moon's orbital positions around Earth and Earth around the Sun shift. The visible side of the Moon is variously sunlit, depending on the position of the Moon in its orbit. Thus, this face's sunlit portion can vary from 0% (at new moon) to 100% (at full moon). Each of the 4 major lunar phases (see below) is ~7.4 days, with +/− 19 hours in variation (6.58–8.24 days) due to the elliptical shape of the Moon's orbit. Phases of the Moon There are four ''principal'' (primary/major) lunar phases ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crossaster Papposus
The common sunstar is a species of sea star (aka starfish) belonging to the family Solasteridae. It is found in the northern parts of both the Atlantic and the Pacific Oceans. Distribution The common sunstar is distributed from the Arctic down to the English Channel, in the North Sea, also on both East (from the Arctic to the Gulf of Maine) and Pacific coasts (from Alaska to Puget Sound) of North America. It is also circumboreal, found in Greenland, Iceland, the Barents Sea, Kola Bay, Okhotsk Sea and the White Sea. Habitat The common sunstar is commonly found on rocky bottoms, coarse sand and gravel in the bathyal, infralittoral and circalittoral zone (from low-tide line up to depths of 300 m). It seems to prefer areas of high water movement. Very small sunstars are sometimes found in rock pools. Description It is reddish on top with concentric bands of white, pink, yellow, or dark red, and it is white on the underside. It is covered on top with brushlike spines, with t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epibiont
An epibiont (from the Ancient Greek meaning "living on top of") is an organism that lives on the surface of another living organism, called the basibiont ("living underneath"). The interaction between the two organisms is called epibiosis. An epibiont is, by definition, harmless to its host. In this sense, the interaction between the two organisms can be considered neutralistic or commensalistic; as opposed to being, for example, parasitic, in which case one organism benefits at the expense of the other, or mutualistic, in which both organisms obtain some explicit benefit from their coexistence. Examples of common epibionts are barnacles, remoras, and algae, many of which live on the surfaces of larger marine organisms such as whales, sharks, sea turtles, and mangrove trees. Although there is no direct effect of the epibiont to the host, there are often indirect effects resulting from this interaction and change in the surface of the host. This has been found to be especially i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Leptasterias Polaris
''Leptasterias polaris'', the polar six-rayed star, is a species of starfish in the family Asteriidae. It is found in cold waters in the northwest Atlantic Ocean and in polar regions. Description ''Leptasterias polaris'' is a small, slow growing, compact starfish with six arms. The aboral (upper) surface has a covering of blunt spiny plates and is usually some shade of brown or grey. Distribution and habitat ''Leptasterias polaris'' occurs in the north west Atlantic Ocean from the Gulf of Maine northwards, and in Arctic waters. It has also been found in the Azores and European waters. Biology ''Leptasterias polaris'' is a major predator in the cold waters in which it lives. Young individuals are mostly found on rocks less than deep and feed on such bivalve molluscs as the blue mussel ('' Mytilus edulis'') and ''Hiatella arctica''. Older individuals move to deeper waters where the seabed is sand or mud and feed on clams such as the Greenland cockle (''Serripes groenlandicus'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Predation
Predation is a biological interaction In ecology, a biological interaction is the effect that a pair of organisms living together in a community have on each other. They can be either of the same species (intraspecific interactions), or of different species ( interspecific interactio ... where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the host) and parasitoidism (which always does, eventually). It is distinct from scavenging on dead prey, though many predators also scavenge; it overlaps with herbivory, as seed predators and destructive frugivores are predators. Predators may actively search for or pursue prey or wait for it, often concealed. When prey is detected, the predator assesses whether to attack it. This may involve ambush predation, ambush or pursuit predation, sometimes after stalking the prey. If the attack ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nematocyst
A cnidocyte (also known as a cnidoblast or nematocyte) is an explosive cell containing one large secretory organelle called a cnidocyst (also known as a cnida () or nematocyst) that can deliver a sting to other organisms. The presence of this cell defines the phylum Cnidaria (corals, sea anemones, hydrae, jellyfish, etc.). Cnidae are used to capture prey and as a defense against predators. A cnidocyte fires a structure that contains a toxin within the cnidocyst; this is responsible for the stings delivered by a cnidarian. Structure and function Each cnidocyte contains an organelle called a cnida, cnidocyst, nematocyst, ptychocyst or spirocyst. This organelle consists of a bulb-shaped capsule containing a coiled hollow tubule structure attached to it. An immature cnidocyte is referred to as a cnidoblast or nematoblast. The externally oriented side of the cell has a hair-like trigger called a cnidocil, which is a mechano- and chemo-receptor. When the trigger is activated, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesentery (zoology)
In zoology, a mesentery is a membrane inside the body cavity of an animal. The term identifies different structures in different phyla: in vertebrates it is a double fold of the peritoneum enclosing the intestines; in other organisms it forms complete or incomplete partitions of the body cavity, whether that is the coelom or, as in the Anthozoa, the gastrovascular cavity. The word "mesentery" is derived from the Greek ''mesos'', "in the middle" and ''enteron'', an "intestine". Vertebrates In vertebrates, a mesentery is a membrane consisting of a double fold of peritoneum that encloses the intestines and their associated organs and connect them with the dorsal wall of the abdominal cavity. In invertebrates, a mesentery is a support or partition in a body cavity serving a similar function to the mesenteries of vertebrates. Bilateria In bilaterally symmetrical organisms there is often a major mesentery separating the two halves of the coelom. In segmented organisms such as eart ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monotypic Taxon
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispecific" or "monospecific" is sometimes preferred. In botanical nomenclature, a monotypic genus is a genus in the special case where a genus and a single species are simultaneously described. In contrast, an oligotypic taxon contains more than one but only a very few subordinate taxa. Examples Just as the term ''monotypic'' is used to describe a taxon including only one subdivision, the contained taxon can also be referred to as monotypic within the higher-level taxon, e.g. a genus monotypic within a family. Some examples of monotypic groups are: Plants * In the order Amborellales, there is only one family, Amborellaceae and there is only one genus, '' Amborella'', and in this genus there is only one species, namely ''Amborella trichopoda.' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siphonoglyph
The siphonoglyph is a ciliated groove at one or both ends of the mouth of sea anemones and some corals. The siphonoglyph extends into a pharynx and is used to create currents of water into the pharynx. These water currents are important for respiration and maintenance of internal pressure. The presence of a siphonoglyph (or two siphonoglyphs) in several anthozoans (including species from the orders Zoantharia, Ceriantharia, Antipatharia Antipatharians, also known as black corals or thorn corals, are an order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of or ..., and Octocorallia) introduces an element of bilateral symmetry into the particular species' body plan (Beklemishev 1969). Some have argued that the presence of bilateral symmetry in these anthozoans is evidence that the ancestor to bilaterians and cnidarians may have had a bilaterally symmetrica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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