|
|
| (2 intermediate revisions by the same user not shown) |
| Line 1: |
Line 1: |
| − | {{dablink|Mother of Pearl redirects here. For the novel, see [[Mother of Pearl (novel)]]}}
| + | 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.
| + | |
| − | [[Image:NautilusCutawayLogarithmicSpiral.jpg|thumb|right|225px|The iridescent nacre of a [[Nautilus]] ]] | + | == Shell formation == |
| | | | |
| − | == Description ==
| + | [[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. | + | 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.
| + | 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 [[guitar]]s. | + | == 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 [[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.
| + | 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.
| + | 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. |
| | | | |
| − | Nacre is composed of a 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]].
| + | == See also == |
| | + | * [[Aperture (mollusc)|Aperture]] |
| | + | * [[Columnella]] |
| | + | * [[Operculum (gastropod)|Operculum]] |
| | | | |
| − | 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.
| + | [[Category:Animal anatomy]] |
| | + | [[Category:Molluscs]] |
| | | | |
| − | 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.
| + | [[pt:Manto (molusco)]] |
| − | | + | [[ru:Мантия моллюсков]] |
| − | 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 [[guitar]]s.
| |
| − | | |
| − | 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.
| |
| − | | |
| − | 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.
| |
| − | | |
| − | ==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==
| |
| − | *Lin, A., and Meyers, M.A. (2005). Growth and structure in abalone shell, ''Materials Science and Engineering A'' '''390'''(Jan. 15):27–41 ([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 ])
| |
| − | *Mayer, G. (2005). [http://www.sciencemag.org/cgi/content/abstract/310/5751/1144 Rigid biological systems as models for synthetic composites]. ''Science'' '''310''':1144–1147
| |
| − | *{{cite journal | quotes=no|author = Ortiz C. ''et al.''|year=September 2005|title = Nanoscale morphology and indentation of individual nacre tablets from the gastropod mollusc ''Trochus niloticus''|journal= J. Mater. Res.|volume= 20|issue=9}} [http://web.mit.edu/cortiz/www/Ben/BenPaperRevisedFinal.pdf pdf file on line]
| |
| − | | |
| − | ==See also==
| |
| − | {{Wiktionary}}
| |
| − | * [[Ammolite]]
| |
| − | | |
| − | [[Category:Mollusc products]]
| |
| − | [[Category:Pearls]]
| |
| − | | |
| − | [[de:Perlmutt]]
| |
| − | [[es:Nácar]]
| |
| − | [[fr:Nacre]]
| |
| − | [[nl:Parelmoer]] | |
| − | [[pl:Masa perłowa]]
| |
| − | [[pt:Madrepérola]]
| |
| − | [[sv:Pärlemor]]
| |
| − | [[tr:Sedef]]
| |
| − | [[vi:Xà cừ (vật liệu)]]
| |
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
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
pt:Manto (molusco)
ru:Мантия моллюсков
