, which has a large aperture and a pronounced parietal callus . The aperture is an opening in certain kinds of mollusc shell s it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc. The term aperture is used for the main opening in gastropod ... a main anterior aperture and a smaller posterior aperture. As well as the aperture, some gastropod shells ... keyhole limpets where the central smaller opening at the apex mollusc apex of the shell is called ... called orifices. In gastropods In some prosobranch gastropods, the aperture of the shell can be closed, and even completely sealed, with a sort of door or operculum gastropod operculum . The aperture ... roughly to the cross section of the body whorl of the shell. The aperture of a snail shell can have many other forms semicircular, trilobate or auriculate . In some gastropods, the aperture is narrowed ... layers to the aperture margin also called peristome from the mantle border, the principal agent in the secretion of the shell. Terminology The margin of the aperture is sometimes continuous or entire ... side of the aperture being formed only by the body whorl. For convenience of reference, the margin of a gastropod aperture is divided into three areas The parietal wall with the outer lip labrum the area ... at its base. The palatal wall the outer free wall of the final whorl of the shell. The aperture ... . Shape The shape of the aperture can be auriform, ear shaped, as in Auriculella bean for example ... Aperture shape&state Bean Aperture shape Bean . accessed 3 January 2011. ref circular, rotundate, orbicular. claw shaped aperture Some Melongenidae have a claw shaped aperture. crescent examples ... Molluscs&character Aperture shape&state Crescent Aperture shape Crescent . accessed 3 January 2011. ref distorted aperture Personidae has a distorted aperture. linear, narrow. Cypraea , Conus ... Aperture shape&state Half moon Aperture shape Half moon . accessed 3 January 2011. ref . Nerita ... more details
other uses Image Aperures.jpg thumb A large 1 and a small 2 aperture Image Aperture in Canon 50mm f1.8 II lens.jpg thumb right Aperture mechanism of Canon 50mm f 1.8 II lens Image ApertureDefn1707.png right thumb 244px Definitions of Aperture in the 1707 Glossographia Anglicana Nova ref Thomas Blount .... Gregory, Mr. Lock, Mr. Evelyn, Mr. Dryden, Mr. Blunt, &c. , London, 1707. ref In optics , an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical ... optics focus in the image plane . The aperture determines how collimated the admitted rays are, which is of great importance for the appearance at the image plane. If an aperture is narrow, then highly collimated rays are admitted, resulting in a sharp focus at the image plane. If an aperture ... focal length. This means that a wide aperture results in an image that is sharp around what the lens is focusing on and blurred otherwise. The aperture also determines how many of the incoming rays are actually admitted and thus how much light reaches the image plane the narrower the aperture, the darker ... , and the aperture stop is the stop that determines the ray cone angle, or equivalently the brightness, at an image point. In some contexts, especially in photography and astronomy , aperture refers to the diameter of the aperture stop rather than the physical stop or the opening itself. For example, in a telescope the aperture stop is typically the edges of the objective lens or mirror or of the mount that holds it . One then speaks of a telescope as having, for example, a 100 centimeter aperture . Note that the aperture stop is not necessarily the smallest stop in the system. Magnification and demagnification by lenses and other elements can cause a relatively large stop to be the aperture stop for the system. Sometimes stops and diaphragms are called apertures, even when they are not the aperture stop of the system. The word aperture is also used in other contexts to indicate a system ... more details
Unreferenced stub auto yes date December 2009 Lirae singular lira are fine lines or ridges much finer than ribs that are a sculpture mollusc sculptur al feature of the outside of the shells of various animals. The term is commonly applied to the mollusc shell shells of mollusc s such as gastropod s, bivalve s and nautiloid s. It can also be used to describe similar sculpture on the surface of the shells of brachiopod s. In addition the word is used to describe fine linear elevations of shelly material within the outer lip of the aperture mollusc aperture of some gastropod shell s. The adjectival form of the word is lirate . References reflist DEFAULTSORT Lira Mollusc Category Mollusc anatomy Mollusc stub animal anatomy stub ... more details
File Neverita josephinia 000.JPG thumb The shell of the sea snail Neverita josephinia has an umbilical callus which almost completely fills the umbilicus, leaving only a groove and a chink on one side. File Semicassis pyrum base .JPG thumb The shell of the sea snail Semicassis pyrum , has a large aperture and a pronounced parietal callus A callus is an anatomical feature that exists in some Mollusc shell mollusk shells , a thickened area of shell material that can partly or completely covers the umbilicus mollusc umbilicus , or can be located on the body whorl near the aperture mollusc aperture of the shell i.e. a parietal callus or columella gastropod columellar callus . A callus exists in the shells of various species of gastropods snails and also in the shells of several species of Nautilus , a cephalopod . References http www.conchsoc.org aids to id gastropod parts.php Definitions of terms for parts of gastropod shell reflist Refimprove date August 2011 Category Mollusc anatomy ... more details
Apex adjectival form apical is an anatomical term for the tip of the mollusc shell of a gastropod , scaphopod , or cephalopod mollusk mollusc . Gastropods The word apex is most often used to mean the tip of the spire mollusc spire of the shell of a gastropod . The apex is the first formed, and therefore the oldest, part of the shell. To be more precise, the apex would usually be where the tip of the Embryo embryonic shell or protoconch is situated, if that is still present in the adult shell often it is lost or eroded away . Coiled gastropod shells The phrase apical whorls , or protoconch , means the whorls that constitute the embryonic shell at the apex of the shell, especially when this is clearly distinguishable from the later whorls of the shell, otherwise known as the teleoconch . Comparison of the apical part and the whole shell of Otukaia kiheiziebisu gallery File Calliostoma kiheiziebisu apex.png File Calliostoma kiheiziebisu shell.png gallery Limpet like gastropod shells The space under the apex of a Patellidae patellate gastropod is called the apical cavity . Scaphopods The apex of Scaphopoda tusk shells is the small, open posterior end, and the opening itself is usually called the apical aperture . Cephalopods In orthocone cephalopods, the pointed end of the shell is called the apex, and shell growth is away from the apex and toward the aperture . The first chamber of the apex is sometimes called the protoconch . Bivalves The apex of a valve of a bivalve is more usually known as the umbo or beak. When the embryonic shell is still present that is known as the prodissoconch . References Category Mollusc anatomy Category Gastropods Gastropod stub ... more details
wiktionarypar aperture The aperture of an optical system is the opening that limits the amount of light that can pass through. Aperture may also refer to TOC right Do not add Aperture Science in this article. It is not ambiguous with aperture . Per WP MOSDAB , it does not belong on this disambiguation page see talk page for details. Science and technology Aperture antenna , a physical parameter of an antenna Aperturemollusc , the main opening in the shell of a gastropod or scaphopod molluscAperture botany , a weaker spot in the wall of a pollen grain Numerical aperture is a parameter used to describe optical systems Computers Aperture computer memory , a region of the physical address space that opens access to a particular device or memory unit Aperture software , an image organization and editing program for photographers, sold by Apple Inc. Other Aperture typography , an enclosed loop in a typographical symbol such as the lower part of the letter a Aperture magazine Aperture magazine , a long running art photography magazine See also Lookfrom Aperture Includes links to Aperture Science and Aperture Laboratories Intitle Aperture disambig bg cs Clona rozcestn k de Apertur Begriffskl rung es Apertura desambiguaci n nl Apertura ru uk ... more details
, and descending in a screw like manner from the Apex mollusc apex or initial Whorl mollusc whorl to the Aperturemolluscaperture . The shell grows in a regular geometrical progression in its ... the shell with its Apex mollusc apex turned upward from the observer and its Aperturemolluscaperture in view the aperture will be found on the right hand. In others the volutions proceed in the opposite ... being known as the Apex mollusc apex . The word spire is used, in an analogy to a church spire or rock ... Triton or Caecum . The empty Apex mollusc apex in these shells is sometimes very thin, and becomes ... usually have the Whorl mollusc whorls of the spire closely wound and not increasing much in diameter ... cone of Patella , all aperture and no spire. From it there is every gradation, from the Haliotis ... Tryon , Structural and systematic conchology, p.40 1884 ref References reflist Category Mollusc ... more details
riblet. Transverse sculpture Sculpture parallel to the edge of the outer lip of the Aperturemolluscaperture . Tubercle Elevated knob like projections or protrusions larger than a pustule. Varicose Bearing one or more Varix mollusc varices . References reflist DEFAULTSORT Sculpture Mollusc Category Molluscs Category Mollusc anatomy Category Gastropods Category Bivalves ... more details
very high Spire mollusc spired shells with a large number of whorls, and a relatively small Aperturemolluscaperture . The shells of a few genera of gastropods, and of the cephalopod genus Spirula , have ... a quarter higher. ref name Janssen 2007 Terminology Apical whorls the whorls near the apex mollusc apex ... within the egg, and constituting the apex of the shell Protoconch a larval shell of a mollusc also ... Mollusc anatomy ... more details
at the anterior edge of the aperturemolluscaperture instead of a long siphonal canal. The Aplysia .... ref name appesnail The shells of these freshwater snails have simple round aperturemollusc ... extension of the mantle mollusc mantle called a siphon, or inhalant siphon, through which water is drawn ... edge of the Mantle mollusc The mantle cavity mantle cavity . ref http www.marietta.edu biol mussels ... anatomy Cephalopod anatomy Category Cephalopod zootomy Category Mollusc anatomy Category Invertebrate ... Siphon mollusc fi Sifoni biologia sv Sifon biologi zh ... more details
arbustorum The mollusc or mollusk ref group spelling Often spelled mollusk shell in the USA the spelling mollusc is preferred by bruscabrusca ref shell is typically a calcareous exoskeleton which encloses ... live on the land and in freshwater. The ancestral mollusc is thought to have had a shell, but this has ... is the largest extant species of bivalve. The mantle is visible between the open valves A mollusc shell is formed, repaired and maintained by a part of the anatomy called the mantle mollusc mantle . Any ..., and the deposition and rate of crystals is also controlled by hormones produced by the mollusc ... the lifetime of the mollusc by the addition of calcium carbonate to the leading edge or opening. Thus .... However there are many species of gastropod mollusc in which the shell is somewhat reduced or considerably ... is constant. At each point around the aperture of the shell, the rate of growth remains constant. This results ... name Jackson2010 Mollusc shells especially those formed by marine species are very durable and outlast ... mollusc shells date all the way back to the Cambrian period. Large amounts of shells sometimes form ... part of a mollusc however also see Aptychus and operculum gastropod operculum . The shells are usually ... shell in an aplacophoran like ancestral mollusc. ref cite doi 10.1111 j.1469 7998.1968.tb01676.x ... thickened vertical areas are called varices , singular Varix mollusc varix . Varices are typical ... in collections As a structure made primarily of calcium carbonate, mollusc shells are vulnerable to attack ... Seashell surface , a mathematical construct Sculpture mollusc Brachiopod shell protein, papers ... mollusc , with a more historical analysis, see Gary Rosenberg s article at http www.conchologistsofamerica.org ... Shell Space The Snugness Condition . Cephalopod anatomy Category Mollusc anatomy Category Mollusc products Category Cephalopod zootomy br Krogenn et Koda fr Coquille mollusque ... more details
which the inner surface of the shell is coiled, when that space is not filled by a Columella mollusc ... orthostylic, i.e. they have a poorly developed columella mollusc columella . Sometimes there is a dimple ... Umbilicus on a top snail Cephalopod anatomy Category Mollusc anatomy Category Cephalopod zootomy pl ... more details
Image Aeolidia papillosa.jpg thumb Aeolidia papillosa showing cerata along its back the colour of recently eaten food Diverticula is an anatomical term for a set of organs which are visible from the outside on a group of sea slug s known as nudibranch s, which are marine ocean marine opisthobranch gastropod mollusk mollusc s. These diverticula are located within the cerata of a nudibranch and they are parts of the digestive gland of the animal. Because the nudibranch s skin is translucent, the contents of the diverticula are easily visible this means that the nudibranch automatically takes on the exact colour of whatever substrate and food source it is living on and feeding on for example, sea anemone s, hydroid s, etc . Because of this, visually the animal blends perfectly with its environment, providing excellent camouflage . The diverticula are also important because they pass any intact nematocyst s which have been ingested from the food source along to the tips of the cerata, where these stinging cells are then available to defend the nudibranch against predation . References reflist http www.thecephalopodpage.org MarineInvertebrateZoology Spurillaneapolitana.html Category Mollusc anatomy Category Gastropods ... more details
is a fleshy process adapted by its form to digging rather than to locomotion. Formation of mollusc shell see mollusc shell In shelled molluscs, the mantle is what forms the shell, and what adds ... and predators with secreted mucus. See also Mollusc shell , which is formed by the mantle Siphon mollusc which is a part of the mantle in some groups of molluscs References reflist Cephalopod anatomy Category Mollusc anatomy Category Cephalopod zootomy ca Mantell anatomia de Pallium Weichtiere ... pt Manto molusco ru simple Mantle mollusc uk ... more details
File Semicassis Granulata Apertural.jpg thumb One simple varix left on the shell of Semicassis granulata in the Tonnidae Image Biplex perca.jpg thumb Symmetrical varices on the shell of a Biplex species, Ranellidae File Chicoreus palmarosae.jpg thumb Elaborate frilled varices on the shell of Chicoreus palmarosae , Muricidae A varix Pl. varices is an anatomical feature of the gastropod shell shell of certain sea snail s, marine ocean marine gastropod mollusks molluscs . It is a thickened axial ridge in the Animal shell shell of some families of gastropods. A varix is located at intervals around the Whorl mollusc whorl , and is formed by considerable thickening of the outer lip at a resting stage in the growth of the shell. In other words, in gastropods whose shells have varices, the shells are characterised by episodic growth the shell grows in spurts, and during the resting phase the varix forms. Gastropods whose shells have varices are primarily families and species within the taxonomic groups Littorinimorpha and Neogastropoda . In many gastropods bearing varices, for example the Cassinae , the varix is essentially merely a thickening and swelling of the shell at that point. But in some genera within the family Muricidae , such as Chicoreus , Hexaplex , Pteropurpura and Pterynotus , and also within the genus Biplex of the family Ranellidae , the varices are characterised by elaborate ruffles, frills or lamellae. Some other genera, for example Murex , are armed with protective spines which may be straight or curved, and which are formed by the varices closing or curling around their axis. References reflist Category Mollusc anatomy Category Gastropods nl Varix schelpdieren ... more details
File Pleurobranchaea meckelii.jpg thumb A live individual of Pleurobranchaea meckelii the ctenidium is visible as a feather like structure in this view of the right hand side of the animal A ctenidium is a respiratory organ or gill which is found in many mollusks. This structure exists in bivalve s and in many aquatic gastropod s, i.e. in some freshwater snail s and sea snail s and also in some sea slug s. Some aquatic gastropods possess one ctenidium, others have a pair of ctenidia the plural form of the word . A ctenidium is shaped like a comb or a feather, with a central part from which many filaments or plate like structures protrude, lined up in a row. It hangs into the mantle cavity and increases the area available for gas exchange. ref http www.applesnail.net content anatomy respiration.php Respiratory system The apple snail. Retrieved 2012 04 20. ref The word is Latinized but is derived from the Ancient Greek Greek ktenidion which means little comb , being a diminutive of the word kteis meaning comb. References reflist Category Mollusc anatomy Category Invertebrate respiratory system ... more details
File Scallop eyes.jpg thumb right Scallops have up to 100 simple eyes The mollusc s have the widest variety of eye morphologies of any phylum , ref name Serb2008 cite doi 10.1007 s12052 008 0084 1 ref and a large degree of variation in their function. Cephalopod s such as octopus es, squid , and cuttlefish have eyes as complex as those of vertebrates, while scallop s have up to 100 simple eye s. ref Land MF and Fernald RD 1992 http redwood.berkeley.edu vs265 landfernald92.pdf The evolution of eyes Annual review of neuroscience, 15 1 29. ref Diversity Eyes have evolved independently between seven and eleven times in the molluscs, ref http www.mapoflife.org topics topic 282 Camera eyes in gastropod molluscs Camera eyes in gastropod molluscs , mapoflife.org ref which goes some way to explain the diversity of eye types observed. Molluscs have eyes of all levels of complexity, from the pit eyes of many gastropod s, to the pinhole eyes of the Nautilus , to the lensed eyes of the cephalopod s. Compound eyes are present in some bivalves, and reflective mirrors have been innovated by other lineages such as scallop s. ref name Serb2008 As well as varying in complexity, the eyes of molluscs span a huge range in size they may be from 20 m to 27 cm across. ref name Serb2008 Anatomy Gastropods and cephalopods have paired eyes on their heads and sometimes tails , ref name Serb2008 but many molluscs do not have clear head regions in which to locate the eyes. Consequently, many molluscs may have a multitude of eyes in more unlikely places, such as along the edge of their shell. ref name Serb2008 Chiton s have a dispersed network of Aesthete chiton tiny eyes over the surface of their shells which may act together as a compound eye. ref name Serb2008 Many gastropods have stalked eyes the eye can be retracted into the stalk itself in the presence of danger. ref name Serb2008 See Cephalopod eye See also Arthropod eye Parietal eye Sensory organs of gastropods Simple eye in invertebrates ... more details
Image Angular aperture.svg right The angular aperture of a thin lens with focal point at F and an aperture of diameter math d math . thumb 250px The angular aperture of a lens optics lens is the apparent angle of the lens aperture as seen from the Focus optics focal point math a 2 arctan left frac D 2 f right math where math f math is the focal length math D math is the diameter of the aperture . Relation to numerical aperture In a medium with an index of refraction close to 1, such as air, the angular aperture is approximately equal to twice the numerical aperture of the lens. ref cite book title Studies in Optics author Albert Abraham Michelson year 1995 publisher Courier Dover pages 32 isbn 0 486 68700 7 url http books.google.com books?id m2tUZ4 8WGMC&pg PA32&dq 22Angular aperture 22&ie ISO 8859 1&output html ref Formally, the numerical aperture in air is math mathrm NA sin a 2 sin arctan left frac D 2 f right math In the paraxial approximation , with a small aperture, math D f math math mathrm NA approx a 2 math References reflist See also f number Numerical aperture Category Optics Category Angle de ffnungswinkel es Apertura angular it Apertura angolare nl Openingshoek zh ... more details
advert date April 2011 Refimprove date January 2010 Image vt 1.jpg thumb Aperture Gallery in Chelsea, 547 W 27th Street The Aperture Foundation was founded in 1952 by Ansel Adams , Minor White , Barbara Morgan photographer Barbara Morgan , Dorothea Lange , Nancy Newhall , Beaumont Newhall , Ernest Louie, Melton Ferris, and Dody Warren. Their vision was to create a forum for fine art photography, a new concept at the time. The first issue of Aperture magazine was published in spring 1952 in San Francisco. Aperture s efforts increased respect for photography and its popularity among contemporary ... 2010 10 23 chris boot executive director at aperture ref Aperture is a not for profit. The foundation ... have always defined Aperture Foundation, as expressed by the mission statement blockquote The purpose of Aperture Foundation, a non profit organization, is to advance photography in all its forms and to foster the exchange of ideas among audiences worldwide. blockquote Books Aperture is known as publisher ... diane arbus an aperture monograph.html ref Several of Aperture s approximately 20 new titles a year ... two or three new books are the first ever for the artist in question. Aperture also supports .... Exhibitions In 2005, Aperture s three thousand square foot gallery opened in New York s Chelsea art district. ref name aperture http www.aperture.org about ref Many of the shows travel, to a total of more than 25 venues in the U.S. and abroad each year. Aperture s Chelsea gallery regularly ... City. Selection Aperture has exhibited an eclectic and critically acclaimed array of shows, including ... by Josef Koudelka. ref name aperture File Aperture Gallery2.jpg thumb Aperture Gallery in Chelsea, 547 W 27th Street References references External links http www.aperture.org Aperture Foundation Website http thephotobook.wordpress.com 2010 10 23 chris boot executive director at aperture Chris Boot Director Announcement http www.aperture.org diane arbus an aperture monograph.html Diane Arbus Monograph ... more details
Orphan date September 2008 Dynamic aperture is a term in acoustics used very much like aperture in photography. The arrays in side scan sonar can be programmed to transmit just a few elements at a time or all the elements at once. The more elements transmitting, the narrower the beam and the better the Audio bit depth resolution . The ratio of the aperture size to the imaging depth is known as the F number. Dynamic aperture is keeping this number constant by growing the aperture with the imaging depth until the physical aperture cannot be increased. A modern medical ultrasound machine has a typical F number of 0.5. Side Scan Sonar systems produce images by forming angular beams . Beam width is determined by length of the sonar array, narrower beams resolve finer detail. Longer arrays with narrower beams provide finer spatial resolution. Missing image removed Image beam.jpg Category Acoustics physics stub ... more details
Nasal aperture may refer to Posterior nasal apertures Anterior nasal aperture disambig Short pages monitor This long comment was added to the page to prevent it from being listed on Special Shortpages. It and the accompanying monitoring template were generated via Template Long comment. Please do not remove the monitor template without removing the comment as well. ... more details
maximum aperture in hopes of getting enough light for a good exposure. In addition, aperture priority ... its aperture range for a given focal length of the lens. Commonly, lenses provide greatest Angular ... DEFAULTSORT Aperture Priority Category Photography equipment Photo stub be x old de Zeitautomatik ru fi Aukkoautomatiikka sv Slutartidsautomatik th Aperture ... more details
italic title Aperture is a quarterly photography magazine and a book publisher based in Chelsea, Manhattan New York , New York . The magazine is published by Aperture Foundation , a non profit organization devoted to fine art photography . Magazine Inspired by the production quality of Alfred Stieglitz s then defunct Camera Work , Aperture magazine was founded by Minor White , Ansel Adams , Dorothea Lange , Barbara Morgan photographer Barbara Morgan , Nancy Newhall and Beaumont Newhall . ref name ap http www.aperture.org Aperture.org official site ref White, himself a photographer, edited the magazine from its first issue in 1952 until 1975. ref name glbtq cite web url http www.glbtq.com arts white m.html title Minor White 1908 1976 last Lockard first Ray Anne work glbtq.com date 2002 accessdate 2010 04 21 ref He died in 1976. The first iteration of the magazine closed in 1964. Hoffman, a close friend and former student of then editor White, later restored the magazine, becoming its publisher ... houses in the United States and Europe. Aperture agreed to publish Arbus catalog and it was released in time for the show as Diane Arbus An Aperture Monograph . Book publisher Aperture s book publication program began in 1965, with Edward Weston The Flame of Recognition , which became one of Aperture s best selling titles. ref name ap In 1984, Aperture also published The Golden Age of British Photography, 1839 1900 , which featured restored, British Victorian era Victorian Era photography. Aperture Foundation As of 2009, Both Aperture magazine and its book publishing arm are run by the nonprofit arts institution the Aperture Foundation. In 2003, the Foundation instituted the first Aperture Michael E. Hoffman Award, in memory of Michael E. Hoffman died 2001 , who was Aperture s publisher for 37 years. The Aperture Foundation sponsors limited edition portfolios, lectures, conferences and touring ... in 1952 Category Magazines published in New York es Aperture revista ... more details
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