Difference between revisions of "AY Honors/Shells - Advanced/Answer Key"

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{{dablink|Mother of Pearl redirects here. For the novel, see [[Mother of Pearl (novel)]] For the moth, see [[Pleuroptya ruralis]]}}
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The '''mantle''' is an organ found in [[mollusk]]s. It is the dorsal body wall covering the main body, or visceral mass. The [[Epidermis (skin)|epidermis]] of this organ secretes [[calcium carbonate]] to create a shell.
'''Nacre''', also known as '''mother of pearl''', is a naturally occurring organic-inorganic composite.
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[[Image:NautilusCutawayLogarithmicSpiral.jpg|thumb|right|225px|The iridescent nacre of a [[Nautilus]] ]]
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== Shell formation == john
  
== Description ==
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[[Nacre]] is secreted by the [[germ layer|ectodermic]] [[cell (biology)|cells]] of the mantle tissue of most mollusks. Mollusk [[blood]] is rich in a liquid form of [[calcium]]. In these mollusks the calcium is concentrated out from the blood where it can crystallize as calcium carbonate (CaCO<sub>3</sub>). The individual crystals of each layer differ in shape and orientation. Nacre is continually deposited onto the inner surface of the animal's [[animal shell|shell]] (the [[iridescent]] ''nacreous layer'', also known as ''[[Nacre|mother of pearl]]''), both as a means to smoothen the shell itself and as a defense against [[parasite|parasitic organisms]] and damaging detritus.
Nacre is composed of hexagonal platelets of [[aragonite]] ([[calcium carbonate]] (CaCO<sub>3</sub>) [[crystals]]) that are 10-20 µm wide and 0.5 µm thick, arranged in a continuous parallel lamina. The layers of platelets are separated by sheets of organic matrix that are composed of [[elastic]] [[biopolymers]] (such as [[chitin]], [[lustrin]] and [[silk]]-like proteins). This mixture of brittle platelets and the thin layers of elastic biopolymers makes the material strong and resilient. Strength and resilience are also likely to be due to adhesion by the  "brickwork" arrangement of the platelets, which inhibits transverse crack propagation. This design at multiple-length sizes increases its toughness enormously, making it almost equivalent to that of [[silicon]].
 
  
The [[iridescent]] appearance of the nacre is due to the fact that the thickness of the aragonite platelets are about 0.5 micrometres, which is comparable to the wavelength of visible light. This results in constructive and destructive [[interference]] of different wavelengths of light, resulting in different colors of light being reflected at different viewing angles.  
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The calcium carbonate layers are generally of two types: an outer, chalk-like prismatic layer and an inner pearly, lamellar or nacreous layer. The layers may incorporate a substance called [[conchiolin]], often in order to help bind the calcium carbonate crystals together. Conchiolin is composed largely of [[quinone]]-tanned [[protein]]s.
  
Nacre is secreted by the [[epithelial]] [[cell (biology)|cells]] of the [[Mantle (mollusc)|mantle tissue]] of certain species of [[mollusk]]. In these mollusks, nacre is continually deposited onto the inner surface of the animal's shell (the [[iridescent]] ''nacreous layer'', commonly known as ''mother of pearl''), both as a means to smooth the shell itself and as a defense against [[parasite|parasitic organisms]] and damaging detritus.  
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Some shells may also contain pigments, which accounts for the fabulous colours of some [[seashell]]s. These shell pigments may include compounds like [[pyrrole]]s and [[porphyrin]]s, which are also proteins.
  
The iridescent inner layer is considered highly attractive by many cultures and is often used in making [[jewelery]] or as inlays in wood [[furniture]] and fret inlays for  [[guitar]]s.
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== The mantle cavity ==
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A mantle skirt is a double fold of mantle that encloses a water space. This space is called the ''mantle cavity'', and it is a central feature of mollusk biology, containing the mollusk's [[gill]]s, [[anus]], [[osphradium]], [[nephridiopore]]s, and [[gonopore]]s. The mantle cavity may function as a [[Respiration (physiology)|respiratory]] chamber (all mollusks), feeding structure ([[bivalve]]s), brood chamber (several forms), or locomotory organ ([[cephalopod]]s and some bivalves).
  
When a mollusk is invaded by a [[parasite]] or is irritated by a foreign object that the animal cannot eject, a process known as ''[[encystation]]'' entombs the offending entity in successive, concentric layers of nacre. This process eventually forms what we call [[pearl]]s and continues for as long as the mollusk lives.
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The mantle is highly muscular. In cephalopods it is used to force water through a tubular siphon, the [[hyponome]], to propel the animal quickly through the water. In other mollusks, it is used as a kind of "foot" for locomotion.
  
Chief sources are the pearl [[oyster]], found in warm and tropical seas, primarily in [[Asia]]; [[freshwater pearl]] mussels, which live in many rivers of the [[United States]], [[Europe]], and [[Asia]]; and the [[abalone]] of [[California]], [[Japan]], and other [[Pacific Ocean|Pacific]] regions.
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The [[nervous system]] of cephalopods is the most complex of the [[invertebrate]]s. The giant [[nerve]] fibers of the cephalopod mantle have been a favorite experimental material of [[Neurophysiology|neurophysiologists]] for many years.
  
==Decorative uses==
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== See also ==
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* [[Aperture (mollusc)|Aperture]]
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* [[Columnella]]
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* [[Operculum (gastropod)|Operculum]]
  
Both black and white mother of pearl are used for architectural purposes. The natural mother of pearl may be artificially tinted to almost any color.
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[[Category:Animal anatomy]]
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[[Category:Molluscs]]
  
Mother of pearl is also used to clad porcelain sinks. Mother of pearl [[:wikt:tessera|tesserae]] may be cut into artistic shapes and be laminated to ceramic tile and surrounded by numerous coats of colored lacquer to create an artistic design. The lacquer and the mother of pearl are polished at the same time, creating a durable, glossy hard surface.
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[[pl:Płaszcz (anatomia)]]
 
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[[pt:Manto (molusco)]]
It is also available in thin laminated sheet form, allowing easy inlay and cladding work, and modern ceramic tiles.
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[[ru:Мантия моллюсков]]
 
 
Shirt buttons were once often made of mother of pearl, though plastic has largely replaced its use.  Some of the finer-quality clothing companies (e.g., [[Lacoste (company)|Lacoste]], [[Turnbull & Asser (company)|Turnbull & Asser]], and [[Hugo Boss (company)| Hugo Boss]]) still use it, however.
 
 
 
Mother of pearl is a popular style watch dial also found in [[Rolex]] watches.
 
 
 
Key touches and various decorations on musical instruments such as [[saxophone]]s, [[trumpet]]s, [[violin]]s and [[guitar]]s are sometimes made of mother of pearl.  Synthetic key touches made of [[Pyralin]] or similar imitation materials have been affectionately referred to as ''mother of toilet seat'' by musicians.
 
===Tiles===
 
Small, hand-cut shapes with straight edges, called '[[:wikt:tessera|tesserae]]', are laminated to either a [[marble]] or a [[ceramic]] base. The tesserae are hand-placed and closely sandwiched together, creating an irregular mosaic or pattern (such as a weave). The laminated material is typically 1/16 of an inch thick.
 
 
 
===Sheets===
 
Instead of using a marble or tile base, the mother of pearl tesserae are glued to a [[fiberglass]] mesh. The result is a lightweight material that offers a seamless installation, and there is no limit to the sheet size. Mother of pearl sheets may be used on interior floors, exterior and interior walls, countertops, doors and ceilings. Insertion into architectural elements, such as columns or furniture is easily accomplished.
 
 
 
===Clothes===
 
It is used as buttons in the popular Lacoste brand of [[Polo shirt]]s.
 
 
 
===Guitars===
 
It is used as inlays on electric guitar fretboards.
 
 
 
==Gallery==
 
<gallery>
 
image:nacre.jpg|A piece of nacre
 
image:Nacre_microscopic_structure.png|Microscopic structure of nacre—layers of aragonite platelets are separated by protein
 
Image:HoloscaphitesAmmonite.jpg|[[Fossilized]] [[Ammonite]] with nacre shell intact
 
</gallery>
 
 
 
==References==
 
* {{cite journal
 
| first = A.
 
| last = Lin
 
| coauthors = Meyers, M.A.
 
| date = 2005-01-15
 
| title = Growth and structure in abalone shell
 
| journal = Materials Science and Engineering A
 
| volume = 390
 
| pages = 27&ndash;41
 
| url = http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TXD-4DH2DRS-1&_coverDate=01%2F15%2F2005&_alid=256050522&_rdoc=1&_fmt=&_orig=search&_qd=1&_cdi=5588&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=f4efd0a3d7cf3b4a0b8f9861cff4514d
 
| doi = 10.1016/j.msea.2004.06.072
 
}}
 
* {{cite journal
 
| first = G.
 
| last = Mayer
 
| year = 2005
 
| url = http://www.sciencemag.org/cgi/content/abstract/310/5751/1144
 
| title = Rigid biological systems as models for synthetic composites
 
| journal = Science
 
| volume = 310
 
| pages = 1144&ndash;1147
 
}}
 
* {{cite journal
 
| last = Ortiz
 
| first = C.
 
| coauthors = ''et al.''
 
| year = 2005
 
| month = September
 
| title = Nanoscale morphology and indentation of individual nacre tablets from the gastropod mollusc ''Trochus niloticus''
 
| journal = J. Mater. Res.
 
| volume = 20
 
| issue = 9
 
| url = http://web.mit.edu/cortiz/www/Ben/BenPaperRevisedFinal.pdf
 
| doi = 10.1557/JMR.2005.0273
 
}}
 
 
 
==See also==
 
{{Wiktionary}}
 
* [[Ammolite]]
 
 
 
[[Category:Mollusc products]]
 
[[Category:Pearls]]
 
 
 
[[de:Perlmutt]]
 
[[es:Nácar]]
 
[[eo:Perlamoto]]
 
[[fr:Nacre]]
 
[[lt:Perlamutras]]
 
[[nl:Parelmoer]]
 
[[pl:Masa perłowa]]
 
[[pt:Madrepérola]]
 
[[sv:Pärlemor]]
 
[[vi:Xà cừ (vật liệu)]]
 
[[tr:Sedef]]
 

Revision as of 18:30, 7 April 2007

The mantle is an organ found in mollusks. It is the dorsal body wall covering the main body, or visceral mass. The epidermis of this organ secretes calcium carbonate to create a shell.

== Shell formation == john

Nacre is secreted by the ectodermic cells of the mantle tissue of most mollusks. Mollusk blood is rich in a liquid form of calcium. In these mollusks the calcium is concentrated out from the blood where it can crystallize as calcium carbonate (CaCO3). The individual crystals of each layer differ in shape and orientation. Nacre is continually deposited onto the inner surface of the animal's shell (the iridescent nacreous layer, also known as mother of pearl), both as a means to smoothen the shell itself and as a defense against parasitic organisms and damaging detritus.

The calcium carbonate layers are generally of two types: an outer, chalk-like prismatic layer and an inner pearly, lamellar or nacreous layer. The layers may incorporate a substance called conchiolin, often in order to help bind the calcium carbonate crystals together. Conchiolin is composed largely of quinone-tanned proteins.

Some shells may also contain pigments, which accounts for the fabulous colours of some seashells. These shell pigments may include compounds like pyrroles and porphyrins, which are also proteins.

The mantle cavity

A mantle skirt is a double fold of mantle that encloses a water space. This space is called the mantle cavity, and it is a central feature of mollusk biology, containing the mollusk's gills, anus, osphradium, nephridiopores, and gonopores. The mantle cavity may function as a respiratory chamber (all mollusks), feeding structure (bivalves), brood chamber (several forms), or locomotory organ (cephalopods and some bivalves).

The mantle is highly muscular. In cephalopods it is used to force water through a tubular siphon, the hyponome, to propel the animal quickly through the water. In other mollusks, it is used as a kind of "foot" for locomotion.

The nervous system of cephalopods is the most complex of the invertebrates. The giant nerve fibers of the cephalopod mantle have been a favorite experimental material of neurophysiologists for many years.

See also

pl:Płaszcz (anatomia) pt:Manto (molusco) ru:Мантия моллюсков