صدف...گرفته یکی جام هر یک به کف پر از سرخ یاقوت و درّ صدف

[1] - صدف . [ ص َ دَ ] (ع اِ) غلاف مروارید . صدفه یکی . ج ، اصداف . (منتهی الارب ) (دهار). در تحفه ٔ حکیم مؤمن آمده است که با حلزون مرادف است و گویند حیوان او مخصوص به حلزون و پوست صلب او مخصوص صدف است و مراد از مطلق صدف مروارید است . درسیم سرد و خشک و سوخته ٔ او مجفف و جالی و مسدد و حابس اسهال و نزف الدم و نفث الدم و جهت تقویت لثه و رفعزخمهای کهنه و آکله و جلای دندان و نفوخ او جهت رعاف و بخور او جهت بواسیر و طلای او با سفیده ٔ تخم مرغ جهت سوختگی آتش و با ادویه ٔ مناسبه جهت کلف و بَهق و رونق بشره و اکتحال او جهت قرحه ٔ چشم و موی زیاد نافع و ضماد سوخته ٔ خف الغراب و با سرکه جهت ثآلیل و دانه ٔ بواسیر مجرب دانسته اند و قدر شربتش تا یک درهم وبدلش شاخ گاو کوهی سوخته است و مهریارس گوید که صدفی که هنوز مروارید او بسته نشده باشد چون بسوزانند طلای او رفع خنازیر می کند و جالینوس می گوید که صدف هندی محرق بالخاصیة رفع درد فؤاد می کند و چون صدف را نرم سائیده با سرکه بر بناگوش طلا کنند رفع صداع دائمی نزلی کند. (تحفه ٔ حکیم مؤمن ). و در ترجمه ٔ صیدنه ٔ ابوریحان از ارجانی آرد: صدف سوخته دندانها سپید و پاکیزه گرداند و چشم را روشن کند و سپیدی که در چشم پدید آید ببرد و سپید مهره ٔ سوخته را همین خاصیت است و اگر عضوی بر آتش سوخته شود صدف را سوزد و با سرگین گاو با هم بیامیزد و بر سوختگی آتش ضماد کند نیکو شود و اگر گوشت صدف را با عسل بهم بکوبد و با سرگین گاو بیامیزد و با پلکهای چشم طلا کند موی زیاده را از رستن بازدارد. (ترجمه ٔ صیدنه ٔ ابوریحان بیرونی ). و در بحر الجواهر آرد صدف ، جانوری است که در درون او درو لؤلؤ متولد شود واحد آن صدفة. و ج ِ آن اصداف و اصدفة و فارسی آن گوش ماهی است و سپس خواصی را بر طبق آنچه در تحفه و ترجمه ٔ صیدنه آمده برای آن بر شمرده است . (بحر الجواهر). در لاروس بزرگ فرانسه ذیل کلمه ٔناکر آرد: ماده ٔ سخت سفیدرنگی است که ته رنگ آن الوان قوس قزح را دارد و در بیشتر صدف ها یافت می شود و در صنعت و تجارت مورد استفاده است . ناکر از قشر داخلی غلاف بعضی نرم تنان (حیوانات ناعمه ) بوجود می آید و به رنگ های سفید و گلی و آبی و خاکستری است و به مصرف خاتم سازی و ساختن بسیار اززینت آلات ظریف و مخصوصاً دگمه سازی می رسد. مرکز عمده ٔآن فرانسه است و مراکز دیگری که ناکر در آنجا تهیه می شود معمولا همان نقاطی است که در آن مرواریدهای ظریف نیز یافت می گردد مانند کالدونی جدید، شمال و مشرق استرالیا، تائی تی ، جزایر کامبیه و سواحل مکزیک و ماداکاسکار. ناکر از ازمنه ٔ بسیار قدیم مورد توجه بود ومورد استفاده قرار می گرفت . از اواخر قرن پانزدهم مسیحی کلمه ٔ ناکر شایع و مرادف کلمه ٔ چینی استعمال شده است و از آن ظروف ظریف و جامهای زیبا که بر روی آن گاهی نقره و جواهر نیز می نشاندند و گاهی آیینه و نمکدان و دسته ٔ چاقو می ساخته اند. در قرن شانزدهم ناکر برای ساختن بسیاری از اشیاء ظریف مورد استفاده قرار گرفت و در خاتم کاری و مرصعسازی نیز از آن استفاده شده است . در شرق از ناکر برای ترصیع مبل استفاده ٔ فراوان می شد. در قرن هفدهم از ناکر فنجان هم ساخته اند. درقرن نوزدهم آن را برای ساختن جعبه و مجسمه های کوچک و قوطی سیگار و یک نوع خاتم کاری مخصوص بکار بردند، بدان طریق که قطعات صدف را بریده و بر روی کاغذ می چسبانیدند و آن را با آب طلا رنگ آمیزی کرده و بر روی مبل الصاق می کردند و این طرز کار از ایتالیا آغاز شد. از ابتدای قرن بیستم تا بامروز از ناکر برای خاتم سازی و ساختن مهره های شطرنج و نظایر آن استفاده میشود. (از لاروس بزرگ فرانسه ). گاه در تداول فارسی زبانان صدف گویند و حیوانی را که دارای صدف است اراده کنند و در داستانها آرند که صدف در شهر نیسان بروی آب آید و دهن گشاید و قطره ای از باران بدرون گیرد و از آن مروارید بوجود آید، رجوع به لؤلؤ و رجوع به مروارید در این لغت نامه شود. اطوم . ام تومه . ثعثع. (منتهی الارب ). گوش ماهی :  

گرفته یکی جام هر یک به کف
پر از سرخ یاقوت و درّ صدف .

فردوسی .

راست گفتی کنار من صدفست
کاندرو جای خویش ساخت گهر.

فرخی

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صدف‌.  بهترین وی سفیدی بود که در آب شیرین بود و صدف فرفور و صدف فروفس ناسوخته نشاید که استعمال کنند از بهر آنکه بغایت صلب بود و چون بسوزانند قوت وی در غایت تخفیف بود و اولی آن بود که بغایت سحق کنند و این بابی عام است هر چیزی که جوهری و حجری بود پس چون تنها استعمال کنند نافع بود جهت جراحتهای خبیث از بهر آنکه مجفف بود بغیر لذع و چون با سرکه بسرشند و عسل و شراب نافع بود جهت جراحتهای متعفن و خبیث و گوشت صدف بری [حلزون]* چون سحق کرده طلا کنند بدن را خشک گرداند بقوت و صدف جذب سل و عظام بکند و مسکن وجع نقرس و مفاصل بود چون ضماد کنند و چون بسرکه سحق کنند قطع رعاف بکند و وی مسکن درد معده بود چون ضماد کنند و بگذارند تا خود رها کند بغایت نافع بود و چون زن بخود برگیرد حیض براند و گوشت وی سودمند بود جهت گزندگی سگ دیوانه و مرق صدف کوچک شکم براند و بوی بخور کردن اختناق رحم را نافع بود و مشیمه بیرون آورد و صدف سوخته در تحلیل و جلای دندان و در کحلهای چشم مستعمل کنند و ریش چشم را نافع بود و غلظ اجفان زایل کند و چون طلا کنند بر موضعی که موی زیاده در چشم بود بعد از آنکه برکنده باشند دیگر نروید و سوختگی آتش را سود دارد و درد دل را نافع بود و مقدار مستعمل از وی یک مثقال بود و از آب وی سه درم و صدف سوخته بهق را زایل کند و ریشها را پاک گرداند و اسحق گوید خوردن وی مضر بود بمثانه و مصلح آن عسل بود و بدل وی ودع بود

صاحب مخزن الادویه می‌نویسد: صدف بتحریک صاد و دال و فا بهندی سیپ و بفرنگی بلینه نامند و گویند با حلزون مترادف است و شاید حلزون اسم جنس باشد و صدف نوعی از آن یعنی آنچه پوست آن بسیار صلب و پهن و شبیه باستخوان و در صلابت و رخاوت ما بین حجر و عظم باشد آن را صدف و آنچه باشکال مختلفه باشد آن را حلزون نامند

لاتین‌MATER MARGARITARUM -NAERA PERLARUM فرانسه‌NACRE -NACRE DE PERLE انگلیسی ‌MOTHER OF PEARL

اختیارات بدیعی، ص: 267

* حَلَزون یا لیسَک نوعی نرم‌تن در ردهٔ شکم‌پایان است. علت اینکه حلزون را در رده شکم‌پایان قرار داده‌اند؛ این است که در حقیقت تمام قسمت زیرین بدنش، پای آن به شمار می‌رود. زیست‌شناسان تا به امروز بیش از ۳۰ هزار گونه حلزون را شناسایی کرده‌اند. حلزون از محیط زیست بسیار متنوعی برخوردار می‌باشد. محل زندگی بعضی از گونه حلزونها در دریا بوده و بعضی از گونه‌های آن در آبهای شیرین و یا در باغ‌ها زندگی می‌کنند. حلزون از انواع گیاهان تغذیه می‌کند.

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اسم حلزون يطلق على معظم أفراد طائفة البطنقدميات الرخوية التي تتخذ صدفات أو قوقعات لحماية جسدها الرخوي. تتواجد الحلزونات في الماء العذب، المحيطات وعلى البر.

محتويات  [أظهر]

الحركة[عدل]

يتحرك الحلزون بواسطة "قدمه" الذي ينقبض وينبسط، ويفرز مادة مخاطية تعمل على تقليل الاحتكاك بين الأرض وقدم الحلزون، ليسهل حركته. يتحرك الحلزون بمتوسط 47 متر في الساعة، تاركةً خلفه أثراً فضياً لامعاً.

النمو[عدل]

القوقعة تحتوي على خطوط النمو الرفيعة، موازية للفتحة التي توجد بها، والتي تعادل الأوضاع المتوالية التي يأخذها طرف القوقعة أثناء نمو الحيوان، كما أن الحلزون قادر على إصلاحها.

السبات[عدل]

عندما يصوم، يغلق الحلزون قوقعته صانعا صدفة مكونة من طبقة كلسية مخاطية سميكة تحوي ثقوباً لتستمر عملية التنفس، وعندما ينشط الحلزون يفرز مادة تذيب تلك الصدفة ليخرج رأسه وقدمه ويستأنف نشاطه. ذلك الكمون يحدث أيضا عندما تنخفض درجات الحرارة لأقل من خمسة عشر درجة أو في فترات الجفاف، أما الحرارة الرطبة فهى تنعشه.

أقسام جسم الحلزون[عدل]

القوقعة: مخروط حلزوني مجوف صلب رقيق تظهر عليه خطوط النمو ؛ ويتركب من كربونات الكالسيوم (الكلس) بنسبة 75%، ويتراوح قطرها ما بين 25 إلى 40 ملم، وطولها ما بين 25 إلى 35 ملم، ولها 4 أو 5 التفافات، يتباين لونها من حلزون لآخر، وتنحصر بشكل عام بين اللون البني الداكن إلى الكستنائي ذات خطوط صفراء اللون.

الجسم الرخو: طري ولزج، بني رمادي اللون، يمكن إدخاله كاملاً إلى داخل الصدفة عند الإحساس بالخطر أو انعدام النشاط خلال فترات البرد أو الجفاف، ويتألف من:

1- الرأس المشفر وفيه فم له ثلاث شفاه، وأربعة مجسات: اثنان قصيران شمّيان متجهان إلى الأسفل مستكشفين الأرض، بينما ينتهي الآخران بالأعين وهما مرفوعان لأعلى.

2-القدم العضلية، وهي فاتحة اللون وناعمة على عكس باقى الجسم، فهو غامق اللون ومغطى بخطوط عديده.

3- المعطف.

4- الكيس الحشوي.

الحس[عدل]

إن حاسة البصر عند الحلزون بدائية؛ حيث يقوم الحلزون بتحريك المجسين البصريين لمراقبة الوسط المحيط. ولكن حاسة الشم متطورة بفضل المجسين القصيرين الشميين، وحاسة اللمس لديه أيضاً متطورة، وذلك بفضل الخلايا الحسية التي تتوزع بكثرة القدم.

التغذية[عدل]

إن فم الحلزون مقوس، والشفة العلوية مكشكشة تغطي الفك على شكل شفرة صغيرة حادة وثابتة. ويوجد بالداخل اللسان، وهو خشن ومتحرك (لسان الرخويات)، وله شكل مبرد (مبرشة)، وعليه أسنان كيتينية دقيقة عددها نحو 16000 سن تتجدد باستمرار. يتكون غذاء الحلزون لا سيما من الأوراق (الكرنب).وأيضا من الحلويات يفضل أيضا الفاكهة (خاصة الفراولة والشمام). يعد الحلزون من آكلي العشب، ويشكل خطراً على مجموعة كبيرة من النباتات، نظراً للضرر الذي يلحقه بها

فتحات الجسم[عدل]

نرى ثلاث فتحات: - فتحة التناسل والتبويض. - الفتحة التنفسية. - فتحة الشرج والتي يمكن تحديدها عن طريق ظهور خيط رفيع من الفضلات الخضراء.

النقل والتنفس[عدل]

يمتلك الحلزون رئة واحدة تقع في منطقة الجسم المحمية بالقوقعة، ويتم التنفس عن طريق الرئة الوحيدة (تنفس رئوي)، أو عن طريق جلده الرطب (تنفس جلدي). القلب مؤلف من: أذين، وبطين، وشرايين توزع الدم عديم اللون إلى أنحاء الجسم كلها، ويعد جهاز النقل عند الحلزون جهازاً وعائياً دموياً مفتوحاً.

التكاثر[عدل]

الحلزون كائن خنثي (خنثية متقاطعة متوالية)، لكنه لا يلقح نفسه بنفسه؛ لأن النطاف تنضج قبل البويضات، حيث يتزاوج فردان ناضجان جنسياً وتمر النطاف عبر الفوهة التناسلية الموجودة خلف المجس البصري الطويل، ثم يضع كل منهما بيضه في حفر يحفرها بنفسه في الأرض. بعد فترة تمتد من أسبوعين لثلاثة أسابيع، يفقس البيض عن حلزونات صغيرة ذات قواقع شفافة، يصبح ناضجاً بعد ما بين سنة إلى سنتين. ويعمر الحلزون لمدة خمس سنوات تقريبا.

أماكن الانتشار[عدل]

ينتشر الحلزون في المناطق المحيطة بالبحر المتوسط وأوروبا الغربية، ما بين شمال غرب أفريقيا وشرق إيبيريا حتى آسيا الصغرى، إضافة إلى بعض الجزر البريطانية، كما تتواجد على نطاق واسع في مناطق أخرى.

دوره في البيئة[عدل]

يعد أحد آفات الحدائق

يعتبر فريسة لأنواع عديدة من الطيور، السحالي، الحشرات المفترسة، وحلزون قاطع الرأس، ولذلك يعتبر أحياناً وسيلة طبيعية للتخلص من الآفات.

تستخدم أيضاً بعض الوسائل الأخرى، كالمبيدات، أو مواد أقل سمية كالثوم المركز، كما تنفر الحلزونات من النحاس، فيمكن وضع شريط نحاسي حول جذوع الأشجار لردع الحلزونات.

يعتبر هذا النوع من الحلزونات الصالحة للأكل، ويقدم كطبق إسكارغو.

يتم تربية الحلزونات إما لأغراض تجارية بهدف استخدامها في الأطعمة وخلافها، أو كحيوان أليف.

يعتبر هذا الحلزون أيضاً أحد مكونات كريمات البشرة أو الجل التي تباع في المجتمعات اللاتينية، وتستخدم هذه المنتجات لعلاج بعض مشاكل البشرة.

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به پنجابی کونگا:

کونگا اک عام لبن والا نکا جانور اے جیدا جوڑ مولسکا برادری نال ے۔ اینے اپنے دوالے چکر والا خول بنایا ہوندا اے تے ڈر وچ اودے اندر چلا جاندا اے۔ ایہ گلے سڑے پتے کھاکے جی لیندا اے تے وکھریاں تے گلیاں تھاواں تے لبدا اے۔

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به اردو کهونگها:

گھونگھے مختلف جگہوں پر پائے جاتے ہیں، بلوں اور صحراؤں سے لے کر سمندر کی عمیق گہرائیوں تک۔ ان کی اکثریت آبی ہوتی ہے جوکہ میٹھے اور کھارے پانی میں پائے جاتے ہیں۔ زیادہ تر گھونگھے نباتات خور ہوتے ہیں جبکہ ان کی بہت سے اقسام ہمہ خور اور گوشت خور بھی ہوتی ہیں۔ گھونگھا ایک ایسا کیڑا ہے جو اپنی سست روی کی وجہ سے مشہور ہے۔ اس کا گھر اس کی کمر پہ ہی ہے

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به آذری ایلبیز:

İlbiz - (Gastropod) dəstəsindan bir Molyusk növü. İlbizlər yemək yemədən üç il yata bilirlər. Molyusklar 3 sinfə bölünür: qarınayaqlılar, ikitazlılar və başsayaqlılar.

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به ترکی:

Salyangoz, yumuşakçalar (Mollusca) şubesinin Orthogastropoda sınıfındaki kabuklu kara hayvanlarının ortak adı.

Salyangozlar, tatlısularda, denizlerde ve bütün çevrede görülebilen hayvanlardır. Nemli yerlerde bulunurlar veyağışın bol olduğu ve havanın tam soğumadığı sonbahar aylarında sürekli görülürler. Vücutlarında bol miktarda su bulunduğu için çok soğuk havalarda donarlar. Çok sıcak havalarda ise su kaybederek kuruyabilirler. Geçtikleri yerlerde iz bırakmalarını sağlayan parlak renkli sümüksü bir sıvı üretirler. Kabuklarıyla gövdelerinin arasındaki kurumuş sümüksü sıvı, vücutlarındaki nemi kaybetmemelerini sağlar. Kışın toprakaltına ya da ağaç kovuklarına girerek etkinliklerini azaltırlar. Yazın çok sıcak olduğunda da benzer şeklide davranırlar. Çoğunlukla otçul olmakla beraber, etçil ya da omnivor olabilirler. Salyangozlar en çok yağmur yağdığında ortaya çıkarlar

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Snail is a common name that is applied most often to land snails, terrestrial pulmonate gastropod molluscs.

However, the common name "snail" is also applied to most of the members of the molluscan class Gastropoda that have a coiled shell that is large enough for the animal to retract completely into. When the word "snail" is used in this most general sense, it includes not just land snails but also thousands of species of sea snails and freshwater snails. Occasionally a few other molluscs that are not actually gastropods, such as the Monoplacophora, which superficially resemble small limpets, may also informally be referred to as "snails".

Snail-like animals that naturally lack a shell, or have only an internal shell, are mostly called slugs, and land snails that have only a very small shell (that they cannot retract into) are often called semi-slugs.

Contents

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Overview[edit]

Video of snails (most likely Natica chemnitzi and Cerithiumstercusmuscaram) feeding on the sea floor in the Gulf of California, Puerto Peñasco, Mexico, 50 sec

Video of snail after rain, 31 sec

Snails that respire using a lung belong to the group Pulmonata, while those with gills form a polyphyletic group; in other words, snails with gills form a number of taxonomic groups that are not necessarily more closely related to each other than they are related to some other groups. Both snails that have lungs and snails that have gills have diversified so widely over geological time that a few species with gills can be found on land and numerous species with lungs can be found in freshwater. Even a few marine species have lungs.

Snails can be found in a very wide range of environments, including ditches, deserts, and the abyssal depths of the sea. Although land snails may be more familiar to people, marine snails constitute the majority of snail species, and have much greater diversity and a greater biomass. Numerous kinds of snail can also be found in fresh water.

Most snails have thousands of microscopic tooth-like structures located on a ribbon-like tongue called a radula. The radula works like a file, ripping food into small pieces. Many snails are herbivorous, eating plants or rasping algae from surfaces with their radulae, though a few land species and many marine species are omnivores or predatorycarnivores.

Several species of the genus Achatina and related genera are known as giant African land snails; some grow to 15 in (38 cm) from snout to tail, and weigh 1 kg (2 lb).^[1] The largest living species of sea snail is Syrinx aruanus; its shell can measure up to 90 cm (35 in) in length, and the whole animal with the shell can weigh up to 18 kg (40 lb).

Snail moving on a wet ground

Types of snails by habitat[edit]

Main articles: Land snail, Freshwater snail and Sea snail

Slugs[edit]

Main article: Slug

Gastropod species that lack a conspicuous shell are commonly called slugs rather than snails. Some species of slugs have a reduced shell, some have only an internal vestige that serves mainly as a calcium repository, and others have no shell at all. Other than that there is little morphological difference between slugs and snails. There are however important differences in habitats and behaviour.

A shell-less animal is much more maneuverable and compressible, so even quite large land slugs can take advantage of habitats or retreats with very little space, retreats that would be inaccessible to a similar-sized snail. Slugs squeeze themselves into confined spaces such as under loose bark on trees or under stone slabs, logs or wooden boards lying on the ground. In such retreats they are in less danger from either predators or desiccation, and often those also are suitable places for laying their eggs.

Slugs as a group are far from monophyletic; biologically speaking "slug" is a term of convenience with little taxonomic significance. The reduction or loss of the shell has evolved many times independently within several very different lineages of gastropods. The various taxa of land and sea gastropods with slug morphology occur within numerous higher taxonomic groups of shelled species; such independent slug taxa are not in general closely related to one another.

Human relevance[edit]

Helix aspersa - garden snail

Land snails are known as an agricultural and garden pest but some species are an edible delicacy and occasionally household pets.

In agriculture[edit]

There are a variety of snail-control measures that gardeners and farmers use in an attempt to reduce damage to valuable plants. Traditional pesticides are still used, as are many less toxic control options such as concentratedgarlic or wormwood solutions. Copper metal is also a snail repellent, and thus a copper band around the trunk of a tree will prevent snails from climbing up and reaching the foliage and fruit.

The decollate snail (Rumina decollata) will capture and eat garden snails, and because of this it has sometimes been introduced as a biological pest control agent. However, this is not without problems, as the decollate snail is just as likely to attack and devour other gastropods that may represent a valuable part of the native fauna of the region.

As food[edit]

Further information: Land snail § Snails as human food

French cooked snails

In French cuisine, edible snails are served for instance in Escargot à la Bourguignonne. The practice of rearing snails for food is known as heliciculture. For purposes of cultivation, the snails are kept in a dark place in a wired cage with dry straw or dry wood. Coppiced wine-grape vines are often used for this purpose. During the rainy period the snails come out of hibernation and release most of their mucus onto the dry wood/straw. The snails are then prepared for cooking. Their texture when cooked is slightly chewy.

As well as being relished as gourmet food, several species of land snails provide an easily harvested source of protein to many people in poor communities around the world. Many land snails are valuable because they can feed on a wide range of agricultural wastes, such as shed leaves in banana plantations. In some countries, giant African land snails are produced commercially for food.

Land snails, freshwater snails and sea snails are all eaten in a number of countries (principally Spain, Philippines,Morocco, Nigeria, Algeria, Cameroon, France, Italy, Portugal, Greece, Bulgaria, Belgium, Vietnam, Laos, Cambodia, Cyprus, Ghana, Malta, Terai of Nepal, southwestern China, Northeast India states such as Manipur, Tripura and parts of the USA). In certain parts of the world, snails are fried. For example, inIndonesia, they are fried as satay, a dish known as sate kakul. The eggs of certain snail species are eaten in a fashion similar to the way caviar is eaten.

In Bulgaria snails are traditionally cooked in an oven with rice or fried in a pan with vegetable oil and red paprika powder. Before they are used for those dishes however, they are thoroughly boiled in hot water (for up to 90 minutes) and manually extracted from their shells. The two species most commonly used for food in the country are Helix lucorum and Helix pomatia.

Famine food[edit]

Snails and slug species that are not normally eaten in certain areas have occasionally been used as famine food in historical times. Variants of the following event have occurred in Europe from time to time:

In a popular publication quoted below occurs the following notice of a well-known land mollusk, in connection with a traditionary story of the plague, which has long had general currency in Scotland: ‘In the woodlands, the more formidable black nude slug, the Arion or Limax, will also be often encountered. It is a huge voracious creature, herbivorous, feeding, to Barbara’s astonishment, on tender plants; fruits, as strawberries, apples; and even turnips and mushrooms; appearing morning and evening, or after rain; suffering severely in its concealment in long droughts, and remaining torpid in winter. The gray field slug (Limax agrestis) is actually recommended to be swallowed by consumptive patients! In the town of Dundee there exists a strange traditionary story of the plague, connected with the conversion, from dire necessity of the Arion ater, or black slug, to a use similar to that which the luxurious Romans are said to have made of the great apple-snail. Two young and blooming maidens lived together at that dread time, like Bessie Bell and Mary Gray, in a remote cottage on the steep (indeed almost perpendicular) ascent of the Bonnetmaker’s Hill. Deprived of friends or support by the pestilence that walked at noonday, they still retained their good looks and healthful aspect, even when the famine had succeeded to the plague. The jaundiced eyes of the famine-wasted wretches around them were instantly turned towards the poor girls, who appeared to thrive so well whilst others were famishing. They were unhesitatingly accused of witchcraft, and had nearly fallen a prey to that terrible charge; for betwixt themselves they had sworn never to tell in words by what means they were supported, ashamed as they felt of the resource to which they had been driven; and resolved, if possible, to escape the anticipated derision of their neighbours on its disclosure. It was only when about to be dragged before their stern inquisitors, that one of the girls, drawing aside the covering of a great barrel which stood in a corner of their domicile, discovered, without violating her oath, that the youthful pair had been driven to the desperate necessity of collecting and preserving for food large quantities of these Limacinae, which they ultimately acknowledged to have proved to them generous and even agreeable sustenance. To the credit of the times of George Wishart—a glimpse of pre-reforming enlightenment—the explanation sufficed; the young women escaped with their lives, and were even applauded for their prudence.^[2]

Cosmetic[edit]

Skin creams derived from Helix aspersa snails are sold for use on wrinkles, scars, dry skin, and acne. A research study suggested that secretions produced under stress by Helix aspersa might facilitate regeneration of wounded tissue.^[3]

Cultural depictions[edit]

Symbolism[edit]

Because of its slowness, the snail has traditionally been seen as a symbol of laziness. In Christian culture, it has been used as a symbol of the deadly sin ofsloth.^[4][5] Psalms 58:8 uses snail slime as a metaphorical punishment.

Divination and other religious uses[edit]

Land snails (Scutalus sp.) on aMoche pot, 200 AD, Larco Museum Collection, Lima, Peru

Snails were widely noted and used in divination.^[4] The Greek poet Hesiod wrote that snails signified the time to harvest by climbing the stalks, while the Aztec moon god Tecciztecatl bore a snail shell on his back. This symbolised rebirth; the snail's penchant for appearing and disappearing was analogised with the moon.^[6]

Love darts and Cupid[edit]

The use of love darts by the land snailMonachoides vicinus is a form of sexual selection

Professor Ronald Chase of McGill University in Montreal has suggested the ancient myth of Cupid's arrows might be based on early observations of the love dart behavior of the land snail species Helix aspersa.^[7]

Metaphor[edit]

In contemporary speech, the expression "a snail's pace" is often used to describe a slow, inefficient process. The phrase "snail mail" is used to mean regular postal service delivery of paper messages as opposed to the delivery ofemail, which can be virtually instantaneous.

In Indonesia mythology[edit]

·        Keong Emas

See also[edit]

·        Escargot de Quimper

·        Gastropod shell

·        Pasilalinic-sympathetic compass

References[edit]

1.     Jump up^ Fredericks, Anthony D. (2010-03-31). How Long Things Live. Stackpole Books. p. 73. ISBN 9780811736220. Retrieved 19 June 2012.

2.     Jump up^ Chambers, Robert. Domestic annals of Scotland, from the reformation to the revolution. Pub: W. & R. Chambers 1858. May be downloaded from:https://archive.org/details/domesticannalsof02chamiala quoted at http://www.electricscotland.com/history/domestic/vol2ch2c.htm

3.     Jump up^ Brieva, A., Philips, N., Tejedor, R., Guerrero, A., Pivel, J. P., Alonso-Lebrero, J. L., Gonzalez, S. (January 2008). "Molecular basis for the regenerative properties of a secretion of the mollusk Cryptomphalus aspersa". Skin Pharmacology and Physiology 21 (1): 15–21. doi:10.1159/000109084. ISSN 1660-5527.

4.     ^ Jump up to:^a b de Vries, Ad (1976). Dictionary of Symbols and Imagery. Amsterdam: North-Holland Publishing Company. p. 430. ISBN 0-7204-8021-3.

5.     Jump up^ Jack Tresidder, Symbols and Their Meanings, New York: Barnes & Noble, 2006, ISBN 978-0-7607-8164-7, p. 41.

6.     Jump up^ Cooper, JC (1992). Symbolic and Mythological Animals. London: Aquarian Press. p. 213. ISBN 1-85538-118-4.

7.     Jump up^ "Lovebirds and Love Darts: The Wild World of Mating". news.national-geographic.com. National Geographic Society. Retrieved 2010-02-21.

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صدف.  گوشت صدف بیابانی (حلزون )را خرد کنند و بسایند و بر تن بمالند بسیار خشکاننده است . سوخته صدف فرفیری بادشکن ، زداینده و هم قوت عرق نعنا و بونه است .همه انواع صدف های ریزه استخوان و خار را جذب می کنند به شرطی که درسته و بی هیچ تغییر حالتی استعمال شوند .

آرایش :همه پوشش های صدفی و پوسته صدف ها وقتی که می سوزند زداینده لک و پیس اند .صدف خام و ناسوخته پیکانهای استخوانی را جذب

می کند. اگر صدف فرفیری (ارغوانی )را در روغن زیتون بپزند و بر جای مو بمالند از ریزش مو جلوگیری می کند .

ورم و جوش :ماده لزجی که بر حلزون است و آن را زنگ حلزون گویند اگر با کندرو الوا و مر مخلوط کنند تا بر پرمایگی عسل در آید ، ورم بناگوش را خشک می کند و اگر رطوبتی در ژرفا داشته باشد بر می چیند .

زخم و قرحه :سوخته فرفیری زخم را می زداید ،پاک می کند و بهبودی می بخشد . صدف سوخته با نمک داروی سوختگی است و بر سوخته می پاشند تا آن را خشک کند .سوخته هر صدفی برای معالجه مفید است .

در علاج زخم و به ویژه زخمی که بر عصب باشد صدف همراه گوشتش و کندر و مر بر او بگذارند و اگر با گرد آسیاب هم باشد داروی خوبی است و زخم را شفا می دهد .

مفاصل :صدف را ضماد کنند علاج درد مفاصل و نقرس است و ورم مفاصل را فرو می نشاند .

سر :سوخته صدف فرفیری و به ویژه اگر با نمک سوخته شود دندان را جلا می دهد .صدف را بسایند و با سرکه آمیزند خون دماغ را قطع می نماید .

چشم :صدف را با گوشتش بسوزانند و سوخته را بشویند و در چشم بکشند آماس پلک را فرو می نشاند ، سفیدی و تم را از چشک می زداید .

اگر گوشت صدفی را که به (طیلس )کهنه مشهور است بسوزانند و سوخته آن را با قطران بسایند و بر پلک بمالند مانع رویش مو می شود .

ماده لزجی که بر حلزون بیابانی است موی برگشته پلک را می چسباند .

اندام های غذا :گوشت هر صدفی که برشته و نپخته نباشد درد معده را تسکین می دهد .صدف فرفیری را با سرکه بخورند علاج طحال است . ضماد صدف را بر استسقاء بگذارند تا پایین نیاورد جدا نمی شود ، و باید بگذارند تا خودش بیفتد .و به ویژه در علاج استسقاء صدف بیابانی که بسیار خشکاننده است از سایر صدف ها مؤثرتر است .

اندام های راننده :گوشت صدف فرفیری ملین نیست .

گوشت صدفی که مردم شام آن را (طالبیس )می گویند ، تاتر است و به ویژه آبگوشتش ملین است و همچنین آبگوشت صدفهای کوچک ملین است .

دود بر کشیدن از سوخته صدف فرفیری علاج خفگی زهدان است و بچه دان را بیرون می آورد .

دود گوش ماهیهای ساحلی از قبیل بابلی ، قلزمی ، در علاج خفگی زهدان مفید است و صرع زدگان را به هوش می آورد .

صدف را بردارند حیض را ریزش می دهد .

زهرها :گوشت صدف پادزهر سگ هار است .

.

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صَدَف چروک نامی است که برای گروهی از جانوران نرم‌تن دوکفه‌ای استفاده می‌شود. بیشتر صدف‌های خوراکی در دریاها و آب‌های شور زندگی می‌کنند.

این جانوران دو صدف سفت آهکی دارند که تن نرمشان را دربر گرفته‌است. آب‌شش‌های آن‌ها پلانکتون‌ها را از آب غربال می‌کند وماهیچه‌های نزدیک‌کننده نیرومندی در تن آن‌ها برای بسته نگه داشتن کفه‌ها به‌کار می‌رود که همین قسمت ماهیچه‌ای را بعد از پختن مورد مصرف قرار می‌دهند.

نگارخانه[ویرایش]

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منابع

Wikipedia contributors، "Oyster،" Wikipedia، The Free Encyclopedia، http://en.wikipedia.org/w/index.php?title=Oyster&oldid=213871099 (accessed May ۲۱، ۲۰۰۸).

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صَدَف چروک نامی است که برای گروهی از جانوران نرم‌تن دوکفه‌ای استفاده می‌شود. بیشتر صدف‌های خوراکی در دریاها و آب‌های شور زندگی می‌کنند.

این جانوران دو صدف سفت آهکی دارند که تن نرمشان را دربر گرفته‌است. آب‌شش‌های آن‌ها پلانکتون‌ها را از آب غربال می‌کند وماهیچه‌های نزدیک‌کننده نیرومندی در تن آن‌ها برای بسته نگه داشتن کفه‌ها به‌کار می‌رود که همین قسمت ماهیچه‌ای را بعد از پختن مورد مصرف قرار می‌دهند.

نگارخانه

·        

·        

منابع

Wikipedia contributors، "Oyster،" Wikipedia، The Free Encyclopedia، http://en.wikipedia.org/w/index.php?title=Oyster&oldid=213871099 (accessed May ۲۱، ۲۰۰۸).

به آذری:

Stridiya — (Ostrea) molyusklar tipinin ikitaylılar sinifindən ilbiz. Çanaqlar bir-birinə bağlayıcı əzələlər ilə bağlanır. Substrata yapışdığına görə ayaq və bissus vəzisi reduksiya olunmuşdur. Suyu süzməklə qidalanır. Bir Stridiya suyun tempraturundan asılı olaraq saatda 1-3 litr suyu süzür. Ayrıcinsiyyətli və hermafroditdir. İriləri bir neçə mln yumurta verir. Stridiyaların çoxu tropik və subtropik dənizlərdə yaşayır. Vətəgə əhəmiyyəti var Qara dəniz və Yapon dənizində böyük ehtiyyatı var. Yeyilir. Bir sıra ölkələrdə süni surətdə artırılır.

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به ترکی:

İstiridye, yumuşakçalar (Mollusca) şubesinin yassı solungaçlılar sınıfından, ılıman ve sıcak denizlerde toplu halde yaşayan çift kabuklu bir hayvan.

Zemine yapışan kabuk çukur ve büyük, üstte kalan kabuk ise düz ve daha küçüktür. İstiridyenin kabukları, derisinin salgısıdır. Kabuğun üst yüzeyi sert ve pürüzlüdür.

İstiridyeler, midyeler gibi bulundukları yerde sabit kalırlar. Ayakları ve kafaları yoktur ve yer değiştiremezler. Kalpleri, sinir sistemleri ve kabukları arasında tek bir kabuk kapayıcı kasları vardır. Solungaç solunumu yaparlar. Kabukların aralanmasıyla sudaki oksijen solungaç tarafından soğurulur. Bu yolla sudaki bitkisel ve hayvansal planktonları da alarak beslenirler.

Çoğu hermafrodit olmakla beraber ayrı eşeyli olanları da vardır. Atlas Okyanusu ve Kuzey Amerika'nın Büyük Okyanus kıyılarında bol rastlanan Virginia istiridyelerinin bazı türleri beşinci aya kadar erkek olarak yaşar ve sonraki aylarda dişiye dönüşerek yumurtlamaya başlarlar. İstiridyeler gri bir toz biçiminde milyonlarca yumurta döker. Bu yumurtalar denizde döllenir. Döllenen yumurtalar birkaç gün içinde açılır ve içinden larvalar çıkar. Bu larvalar bir iki gün serbestçe yüzdükten sonra sert zeminlere yapışırarak tutunurlar ve hayatları boyunca bu noktada sabit kalırlar.

Bir çok ülkede insanlar tarafından besin kaynağı olarak tüketilmesinin yanında, deniz yıldızları, balıklar,ahtapotlar tarafından da tüketilmektedir. Yiyecek olarak tüketim, çamurlu zeminler ve kirli sular sebebiyle az sayıda istiridye hayatta kalabilmektedir. Besin ortamı zengin bölgelerde 50 yıl kadar yaşayabilenleri vardır.

İstiridyelerin içindeki inci bir servet kaynağıdır. Kabukları arasında kalan kum veya kurt gibi yabancı maddelerisedef salgılarıyla örterek inci meydana getirirler. İnci 2-3 yılda meydana gelir. Basra Körfezinde Seylan Adaları,Bahreyn Adaları çevresinde ve Kaliforniya sahillerinde inci istiridyeleri avlanır. Hatta özel olarak inci tavlaları kurulur. Bir tek inci için bazen bin kadar inci istiridyesi açılır. Amerika'da istiridyelerin içlerinde inci olup olmadığıröntgen ile yoklanır. Boş olanlar tekrar denize atılır. Yüksek değerli siyah inciler Meksika Körfezinden çıkarılır. İstiridyecilik, istiridye tavlalarında yapılır. İstiridye üreticileri larvaların tutulması için temiz zeminler hazırlamak zorundadır. Çünkü çamurlu tabaka onların ölümüne sebep olur. Bu maksatla istiridye kabukları veya tuğlalar kullanılır. En iyi istiridyeler akıntılı sularda yetişir. Çünkü böyle sular temiz ve bol besin taşırlar. Lağımlı sularda bulunan istiridyeler veba ve tifo hastalıklarına sebep olabilir.

Familyası

İstiridyegiller (Ostreidae)

Yaşadığı yerler

Ilıman ve sıcak denizlerde sürüler halinde yaşar.

Özellikleri

İki parçadan meydana gelen kabukları kalın ve katmerlidir. Parçalar eşit büyüklükte değildir. Sol kabuk çukur olup, bununla vücudunu zemine bağlar. Düz olan üst kavkı (kabuk) kapak vazifesi görmektedir.

Ömrü

10 yıldan fazladır.

Çeşitleri

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The word oyster is used as a common name for a number of different families of saltwater clams, bivalve molluscs that live in marine or brackish habitats. In some species the valves are highly calcified, and many are somewhat irregular in shape. Many, but not all, oysters are in the superfamily Ostreoidea.

Some kinds of oysters are commonly consumed by humans, cooked or raw, the latter being a delicacy. Some kinds ofpearl oysters are harvested for the pearl produced within the mantle. Windowpane oysters are harvested for their translucent shells, which are used to make various kinds of decorative objects.

Contents

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Etymology[edit]

First attested in English during the 14th century,^[1] the word "oyster" comes from Old French oistre, in turn from Latin ostrea, the feminine form of ostreum,^[2] which is the latinisation of the Greek ὄστρεον (ostreon), "oyster".^[3] Compare ὀστέον (osteon), "bone".^[4]

Types[edit]

True oysters[edit]

True oysters are members of the family Ostreidae. This family includes the edible oysters, which mainly belong to the genera Ostrea, Crassostrea, Ostreola, and Saccostrea. Examples include the Belon oyster, eastern oyster, Olympia oyster, Pacific oyster, and the Sydney rock oyster.

Pearl oysters[edit]

Removing a pearl from a pearl oyster

Main article: Pearl oyster

Almost all shell-bearing mollusks can secrete pearls, yet most are not very valuable.

Pearl oysters are not closely related to true oysters, being members of a distinct family, the feathered oysters (Pteriidae). Both cultured pearls and natural pearls can be extracted from pearl oysters, though other molluscs, such as the freshwater mussels, also yield pearls of commercial value.

The largest pearl-bearing oyster is the marine Pinctada maxima, which is roughly the size of a dinner plate. Not all individual oysters produce pearls naturally. In fact, in a harvest of two and a half tons of oysters, only three to four oysters produce what commercial buyers consider to be absolute perfect pearls.^{[citation needed]}

In nature, pearl oysters produce pearls by covering a minute invasive object with nacre.^[5] Over the years, the irritating object is covered with enough layers of nacre to become a pearl. The many different types, colours and shapes of pearls depend on the natural pigment of the nacre, and the shape of the original irritant.

Pearl farmers can culture a pearl by placing a nucleus, usually a piece of polished mussel shell, inside the oyster. In three to seven years, the oyster can produce a perfect pearl. These pearls are not as valuable as natural pearls, but look exactly the same. In fact, since the beginning of the 20th century, when several researchers discovered how to produce artificial pearls, the cultured pearl market has far outgrown the natural pearl market.

Other types of oysters[edit]

A number of bivalve molluscs (other than true oysters and pearl oysters) also have common names that include the word "oyster", usually because they either taste like or look somewhat like true oysters, or because they yield noticeable pearls. Examples include:

·         Thorny oysters in the genus Spondylus

·         Pilgrim oyster, another term for a scallop, in reference to the scallop shell of St. James

·         Saddle oysters, members of the Anomiidae family also known as jingle shells

·         Dimydarian oysters, members of the family Dimyidae

·         Windowpane oysters

·        

Crassostrea gigas

·        

Crassostrea gigas, opened

In the Philippines, a local thorny oyster species known as Tikod Amo is a favorite seafood source in the southern part of the country.^[6] Because of its good flavor, it commands high prices.

Anatomy[edit]

Oysters are filter feeders, drawing water in over their gills through the beating of cilia. Suspended plankton and particles are trapped in the mucus of a gill, and from there are transported to the mouth, where they are eaten, digested, and expelled as feces or pseudofeces. Oysters feed most actively at temperatures above 10 °C (50 °F). An oyster can filter up to 5 l (1.3 US gal) of water per hour. The Chesapeake Bay's once-flourishing oyster population historically filtered excess nutrients from the estuary's entire water volume every three to four days. Today, that would take nearly a year.^[7] Excess sediment, nutrients, and algae can result in the eutrophication of a body of water. Oyster filtration can mitigate these pollutants.

In addition to their gills, oysters can also exchange gases across their mantles, which are lined with many small, thin-walled blood vessels. A small, three-chambered heart, lying under the adductor muscle, pumps colorless blood to all parts of the body. At the same time, two kidneys, located on the underside of the muscle, remove waste products from the blood. Their nervous system includes two pairs of nerve cords and three pairs of ganglia.

While some oysters have two sexes (European oyster and Olympia oyster), their reproductive organs contain both eggs and sperm. Because of this, it is technically possible (though evolutionarily disadvantageous) for an oyster to fertilize its own eggs. The gonads surround the digestive organs, and are made up of sex cells, branching tubules, and connective tissue.

Once the female is fertilized, she discharges millions of eggs into the water. The larvae develop in about six hours and exist suspended in the water column as veliger larvae for two to three weeks before settling on a bed and maturing to sexual adulthood within a year.

Habitat and behaviour[edit]

Oyster reef at about mid-tide off fishing pier at Hunting Island State Park, South Carolina

A group of oysters is commonly called a bed or oyster reef.

Rocks in intertidal zone covered by oysters, at Bangchuidao Scenic Area,Dalian, Liaoning Province, China

As a keystone species, oysters provide habitat for many marine species. Crassostrea and Saccostrea live mainly in the intertidal zone, while Ostrea is subtidal. The hard surfaces of oyster shells and the nooks between the shells provide places where a host of small animals can live. Hundreds of animals, such as sea anemones, barnacles, andhooked mussels, inhabit oyster reefs. Many of these animals are prey to larger animals, including fish, such asstriped bass, black drum and croakers.

An oyster reef can increase the surface area of a flat bottom 50-fold. An oyster's mature shape often depends on the type of bottom to which it is originally attached, but it always orients itself with its outer, flared shell tilted upward. One valve is cupped and the other is flat.

Oysters usually reach maturity in one year. They are protandric; during their first year, they spawn as males by releasing sperm into the water. As they grow over the next two or three years and develop greater energy reserves, they spawn as females by releasing eggs. Bay oysters usually spawn from the end of June until mid-August. An increase in water temperature prompts a few oysters to spawn. This triggers spawning in the rest, clouding the water with millions of eggs and sperm. A single female oyster can produce up to 100 million eggs annually. The eggs become fertilized in the water and develop into larvae, which eventually find suitable sites, such as another oyster's shell, on which to settle. Attached oyster larvae are called spat. Spat are oysters less than 25 mm (0.98 in) long. Many species of bivalves, oysters included, seem to be stimulated to settle near adult conspecifics.

Pacific oyster Crassostrea gigasequipped with activity electrodes to follow their daily behavior 24/7

Oysters are considered to filter large amounts of water to feed and breathe (exchange O2 and CO2 with water) but they are not permanently open. They regularly shut their valves to enter a resting state, even when they are permanently submersed. In fact their behavior follows very strict circatidal and circadian rhythms according to the relative moon and sun positions. During neap tides, they exhibit much longer closing periods than during the spring tide^[8]
The website MolluSCAN eye is largely devoted to the online study of their daily valve behavior in Europe (France).

Some tropical oysters, such as the mangrove oyster in the family Ostreidae, grow best on mangrove roots. Low tide can expose them, making them easy to collect. In Trinidad in the West Indies, tourists are often astounded when they are told, in the Caribbean, "oysters grow on trees".

The largest oyster-producing body of water in the United States is Chesapeake Bay, although these beds have decreased in number due to overfishing and pollution. Willapa Bay in Washington produces more oysters than any other estuary in the US.^[9] Other largeoyster farming areas in the US include the bays and estuaries along the coast of the Gulf of Mexico from Apalachicola, Florida on the east to Galveston, Texas on the west. Large beds of edible oysters are also found in Japan and Australia. In 2005, China accounted for 80% of the global oyster harvest.^[10]Within Europe, France remained the industry leader.

Common oyster predators include crabs, seabirds, starfish, and humans. Some oysters contain live crabs, known as oyster crabs.

Nutrient cycling[edit]

Bivalves, including oysters, are effective filter feeders and can have large effects on the water columns in which they occur.^[11] As filter feeders, oysters remove plankton and organic particles from the water column.^[12] Multiple studies have shown individual oysters are capable of filtering up to 50 gallons of water per day, and thus oyster reefs can significantly improve water quality and clarity.^{[13][14][15][16]} Oysters consume nitrogen-containing compounds (nitrates and ammonia), phosphates, plankton, detritus, bacteria, and dissolved organic matter, removing them from the water. ^[17] What is not used for animal growth is then expelled as solid waste pellets, which eventually decompose into the atmosphere as nitrogen.^[5] In Maryland, the Chesapeake Bay Program plans to use oysters to reduce the amount of nitrogen compounds entering the Chesapeake Bay by 8,600 t (19,000,000 lb) per year by 2010.^[18]Several studies have shown that oysters and mussels have the capacity to dramatically alter nitrogen levels in estuaries.^[19][20][21] In the U.S., Delaware is the only East Coast state without aquaculture, but making aquaculture a state-controlled industry of leasing water by the acre for commercial harvesting of shellfish is being considered.^[22] Supporters of Delaware's legislation to allow oyster aquaculture cite revenue, job creation, and nutrient cycling benefits. It is estimated that one acre can produce nearly 750,000 oysters, which could filter between 57,000 to 150,000 m³ (15,000,000 to 40,000,000 US gal) of water daily.^[22] Also see nutrient pollution for an extended explanation of nutrient remediation.

Ecosystem services[edit]

As an ecosystem engineer oysters provide "supporting" ecosystem services, along with "provisioning", "regulating" and "cultural" services. (See ecosystem services for service definitions and explanation.) Oysters influence nutrient cycling, water filtration, habitat structure, biodiversity, and food web dynamics.^[23]Oyster feeding and nutrient cycling activities could "rebalance" shallow, coastal ecosystems if restoration of historic populations could be achieved.^[24]Furthermore, assimilation of nitrogen and phosphorus into shellfish tissues provides an opportunity to remove these nutrients from the environment, but this benefit has only recently been recognized.^[24][25][26] In California's Tomales Bay, native oyster presence is associated with higher species diversity of benthic invertebrates^[27] but other ecosystem services have not been studied.^[28] As the ecological and economic importance of oyster reefs has become more widely acknowledged, creation of oyster reef habitat through restoration efforts has become more important- often with the goal of restoring multipleecosystem services associated with natural oyster reefs.^[29]

Human history[edit]

Still-Life with Oysters by Alexander Adriaenssen

The Whaleback Shell Midden inMaine contains the shells from oyster harvested for food dating from 2200-1000 years ago

Middens testify to the prehistoric importance of oysters as food, with some middens in New South Wales, Australia dated at ten thousand years.^[30]They have been cultivated in Japan from at least 2000 BC.^[30] In the United Kingdom, the town of Whitstable is noted for oyster farming from beds on the Kentish Flats that have been used since Roman times. The borough of Colchester holds an annual Oyster Feast each October, at which "Colchester Natives" (the native oyster, Ostrea edulis) are consumed. The United Kingdom hosts several other annual oyster festivals, for example Woburn Oyster Festival is held in September. Many breweries produce Oyster Stout, a beer intended to be drunk with oysters that sometimes includes oysters in the brewing process.

The French seaside resort of Cancale in Brittany is noted for its oysters, which also date from Roman times. Sergius Orata of the Roman Republic is considered the first major merchant and cultivator of oysters. Using his considerable knowledge of hydraulics, he built a sophisticated cultivation system, including channels and locks, to control the tides. He was so famous for this, the Romans used to say he could breed oysters on the roof of his house.^[31]

In Ireland, it is traditional to eat them live with Guinness and buttered brown soda bread.^{[original research?]}

In the early 19th century, oysters were cheap and mainly eaten by the working class. Throughout the 19th century, oyster beds in New York Harbor became the largest source of oysters worldwide. On any day in the late 19th century, six million oysters could be found on barges tied up along the city's waterfront. They were naturally quite popular in New York City, and helped initiate the city's restaurant trade.^[32] New York's oystermen became skilled cultivators of their beds, which provided employment for hundreds of workers and nutritious food for thousands. Eventually, rising demand exhausted many of the beds. To increase production, they introduced foreign species, which brought disease; effluent and increasing sedimentation from erosion destroyed most of the beds by the early 20th century. Oysters' popularity has put ever-increasing demands on wild oyster stocks.^[33] This scarcity increased prices, converting them from their original role as working-class food to their current status as an expensivedelicacy.

In the United Kingdom, the native variety (Ostrea edulis) requires five years to mature and is protected by an Act of Parliament during the May to August spawning season. The current market is dominated by the larger Pacific oysterand rock oyster varieties which are farmed year round.

Fishing from the wild[edit]

Oysters are harvested by simply gathering them from their beds. In very shallow waters, they can be gathered by hand or with small rakes. In somewhat deeper water, long-handled rakes or oyster tongs are used to reach the beds. Patent tongs can be lowered on a line to reach beds that are too deep to reach directly. In all cases, the task is the same: the oysterman scrapes oysters into a pile, and then scoops them up with the rake or tongs.

In some areas, a scallop dredge is used. This is a toothed bar attached to a chain bag. The dredge is towed through an oyster bed by a boat, picking up the oysters in its path. While dredges collect oysters more quickly, they heavily damage the beds, and their use is highly restricted. Until 1965, Marylandlimited dredging to sailboats, and even since then motor boats can be used only on certain days of the week. These regulations prompted the development of specialized sailboats (the bugeye and later the skipjack) for dredging.

Similar laws were enacted in Connecticut before World War I and lasted until 1969. The laws restricted the harvesting of oysters in state-owned beds to vessels under sail. These laws prompted the construction of the oyster sloop-style vessel to last well into the 20th century. Hope is believed to be the last-built Connecticut oyster sloop, completed in 1948.

Oysters can also be collected by divers.

In any case, when the oysters are collected, they are sorted to eliminate dead animals, bycatch (unwanted catch), and debris. Then they are taken to market, where they are either canned or sold live.

Cultivating oysters[edit]

Oyster culture in Riec-sur-Belon,France

Main article: Oyster farming

Oysters have been cultured for well over a century. The Pacific oyster (Crassostrea gigas) is presently the most widely grown bivalve around the world.^[34] Two methods are commonly used, release and bagging. In both cases, oysters are cultivated onshore to the size of spat, when they can attach themselves to a substrate. They may be allowed to mature further to form 'seed oysters'. In either case, they are then placed in the water to mature. The release technique involves distributing the spat throughout existing oyster beds, allowing them to mature naturally to be collected like wild oysters. Bagging has the cultivator putting spat in racks or bags and keeping them above the bottom. Harvesting involves simply lifting the bags or rack to the surface and removing the mature oysters. The latter method prevents losses to some predators, but is more expensive.^[35]

The Pacific or Japanese oyster, Crassostrea gigas, has been grown in the outflow of mariculture ponds. When fish or prawns are grown in ponds, it takes typically 10 kg (22 lb) of feed to produce 1 kg (2.2 lb) of product (dry-drybasis). The other 9 kg (20 lb) goes into the pond and after mineralization, provides food for phytoplankton, which in turn feeds the oyster.

To prevent spawning, sterile oysters are now cultured by crossbreeding tetraploid and diploid oysters. The resulting triploid oyster cannot propagate, which prevents introduced oysters from spreading into unwanted habitats.^[36]

Restoration and recovery[edit]

In many areas, non-native oysters have been introduced in attempts to prop up failing harvests of native varieties. For example, the eastern oyster(Crassostrea virginica) was introduced to California waters in 1875, while the Pacific oyster was introduced there in 1929.^[37] Proposals for further such introductions remain controversial.

The Pacific oyster prospered in Pendrell Sound, where the surface water is typically warm enough for spawning in the summer. Over the following years, spat spread out sporadically and populated adjacent areas. Eventually, possibly following adaptation to the local conditions, the Pacific oyster spread up and down the coast and now is the basis of the North American west coast oyster industry. Pendrell Sound is now a reserve that supplies spat for cultivation.^[38] Near the mouth of the Great Wicomico River in the Chesapeake Bay, five-year-old artificial reefs now harbor more than 180 million nativeCrassostrea virginica. That is far lower than in the late 1880s, when the bay's population was in the billions, and watermen harvested about 910,000 m³(25,000,000 imp bsh) annually. The 2009 harvest was less than 7,300 m³ (200,000 imp bsh). Researchers claim the keys to the project were:

·         using waste oyster shells to elevate the reef floor 25–45 cm (9.8–17.7 in) to keep the spat free of bottom sediments

·         building larger reefs, ranging up to 8.1 ha (20 acres) in size

·         disease-resistant broodstock^[39]

The "oyster-tecture" movement promotes the use of oyster reefs for water purification and wave attenuation. An oyster-tecture project has been implemented at Withers Estuary, Withers Swash, South Carolina, by Neil Chambers-led volunteers, at a site where pollution was affecting beach tourism.^[40]Currently, for the installation cost of $3000, roughly 4.8 million liters of water are being filtered daily. In New Jersey, however, the Department of Environmental Protection refused to allow oysters as a filtering system in Sandy Hook Bay and the Raritan Bay, citing worries that commercial shellfish growers would be at risk and that members of the public might disregard warnings and consume tainted oysters. New Jersey Baykeepers responded by changing their strategy for utilizing oysters to clean up the waterway, by partnering with Naval Weapons Station Earle. The Navy station is under 24/7 security and therefore eliminates any poaching and associated human health risk.^[41] Oyster-tecture projects have been proposed to protect coastal cities, such as New York, from the threat of rising sea levels due to climate change.^[42]

Depuration[edit]

Depuration of oysters is a common industry practice and widely researched in the scientific community but is not commonly known by end consumers. The main objective of seafood depuration is to remove fecal contamination in seafood before being sold to end consumers. Oyster depuration is useful since they are generally eaten raw and in many countries, the requirement to process is government regulated or mandatory. The United Nations Food and Agriculture Organization (FAO) formally recognizes depuration and has published detailed documents on the process,^[43] whereas the Codex Alimentarius, encourages the application of seafood depuration.^[44]

Oyster depuration begins after the harvest of oysters from farmed locations. The oysters are transported and placed into tanks pumped with clean water for periods of 48 to 72 hours. The holding temperatures and salinity vary according to species. The seawater that the oysters were originally farmed in does not remain in the oyster, since the water used for depuration must be fully sterilized, plus the depuration facility would not necessarily be located near the farming location.^[45] Depuration of oysters can remove moderate levels of contamination of most bacterial indicators and pathogens. Well-known contaminants include Vibrio parahaemolyticus which is a bacteria found in seawater animals that is temperature sensitive, and Escherichia coli which is a bacteria found in coastal waters near highly populated cities having sewage systems discharging waste nearby, or from agricultural discharges.^[46]Depuration expands beyond oysters into many shellfish and other related products, especially in seafood that is known to come from potentially polluted areas; depurated seafood is effectively a product cleansed from inside-out to make it safe for human consumption.

As food[edit]

Chargrilled oysters

Wikimedia Commons has media related to Oyster dishes.

Raw oysters presented on a plate

Oysters served on ice and with a piece of lemon on the side

Jonathan Swift is quoted as having said, "He was a bold man that first ate an oyster",^[47] but evidence of oyster consumption goes back into prehistory, evidenced by oyster middens found worldwide. Oysters were an important food source in all coastal areas where they could be found, and oyster fisheries were an important industry where they were plentiful. Overfishing and pressure from diseases and pollution have sharply reduced supplies, but they remain a popular treat celebrated in oyster festivals in many cities and towns.

It was once assumed that oysters were only safe to eat in months with the letter 'r' in their English and French names. This myth is based in truth, in that in the Northern Hemisphere, oysters are much more likely to spoil in May, June, July, and August.^[48] In recent years, pathogens such as Vibrio parahaemolyticus have caused outbreaks in several harvesting areas of the eastern United States during the summer months, lending further credence to this belief.

Nutrition[edit]

Oysters are an excellent source of zinc, iron, calcium, and selenium, as well as vitamin A and vitamin B₁₂. Oysters are low in food energy; one dozen raw oysters contains 110 kilocalories (460 kJ).^[49] They are rich in protein (approximately 9g in 100g of pacific oysters).^[50]

Traditionally, oysters are considered to be an aphrodisiac, partially because they resemble female sex organs.^[51] A team of American and Italian researchers analyzed bivalves and found they were rich in amino acids that trigger increased levels of sex hormones.^[52] Their high zinc content aids the production of testosterone.^[32]

Dietary supplements may contain calcium carbonate from oyster shells, though no evidence shows this offers any benefits beyond what calcium may offer.

Selection, preparation and storage[edit]

Unlike most shellfish, oysters can have a fairly long shelf life of up to four weeks. However, their taste becomes less pleasant as they age. Oysters should be refrigerated out of water, not frozen, and in 100% humidity. Oysters stored in water under refrigeration will open, consume available oxygen, and die.

Freshly opened pearl oysters

Oysters must be eaten alive, or cooked alive. The shells of live oysters are normally tightly closed or snap shut given a slight tap. If the shell is open, the oyster is dead, and cannot be eaten safely. Cooking oysters in the shell kills the oysters and causes them to open by themselves. Traditionally, oysters that do not open have been assumed to be dead before cooking and therefore unsafe.^[53] However, according to at least one marine biologist, Nick Ruello, this advice may have arisen from an old, poorly researched cookbook's advice regarding mussels, which has now become an assumed truism for all shellfish. Ruello found 11.5% of all mussels failed to open during cooking, but when forced open, 100% were "both adequately cooked and safe to eat."^[54]

Giant oyster in southern Angola

Fried oyster with egg and flour is a common dish in Malaysia^[55] andSingapore.

Oysters can be eaten on the half shell, raw, smoked, boiled, baked, fried, roasted, stewed, canned, pickled,steamed, or broiled, or used in a variety of drinks. Eating can be as simple as opening the shell and eating the contents, including juice. Butter and salt are often added. In the case of oysters Rockefeller, preparation can be very elaborate. They are sometimes served on edible seaweed, such as brown algae.

Care should be taken when consuming oysters. Purists insist on eating them raw, with no dressing save perhapslemon juice, vinegar (most commonly shallot vinegar), or cocktail sauce. Upscale restaurants pair raw oysters with a home-made Mignonette sauce, which consists primarily of fresh chopped shallot, mixed peppercorn, dry white wineand lemon juice or sherry vinegar. Like fine wine, raw oysters have complex flavors that vary greatly among varieties and regions: salty, briny, buttery, metallic, or even fruity. The texture is soft and fleshy, but crisp on the palate. North American varieties include: Kumamoto and Yaquina Bay from Oregon, Duxbury and Wellfleet fromCape Cod, Massachusetts, Malpeque from Prince Edward Island, Canada, Blue Point from Long Island, New York,Permaquids from Maine, and Cape May oysters from New Jersey. Variations in water salinity, alkalinity, and mineral/nutritional content influence their flavor profile.

Oysters can contain harmful bacteria. Oysters are filter feeders, so will naturally concentrate anything present in the surrounding water. Oysters from the Gulf Coast of the United States, for example, contain high bacterial loads of human pathogens in the warm months, most notably Vibrio vulnificus and Vibrio parahaemolyticus. In these cases, the main danger is for immunocompromised individuals, who are unable to fight off infection and can succumb tosepticemia, leading to death. Vibrio vulnificus is the most deadly seafood-borne pathogen.

Opening oysters[edit]

Special knives for opening live oysters, such as this one, have short and stout blades.

Fresh oysters must be alive just before consumption or cooking. There is only one criterion: the oyster must be capable of tightly closing its shell. Open oysters should be tapped on the shell; a live oyster will close up and is safe to eat. Oysters which are open and unresponsive are dead and must be discarded. Some dead oysters, or oyster shells which are full of sand may be closed. These make a distinctive noise when tapped, and are known as 'clackers'.

Opening oysters, referred to as oyster-shucking, requires skill. The preferred method is to use a special knife (called an oyster knife, a variant of a shucking knife), with a short and thick blade about 5 cm (2.0 in) long.

While different methods are used to open an oyster (which sometimes depend on the type), the following is one commonly accepted oyster-shucking method.

·         Insert the blade, with moderate force and vibration if necessary, at the hinge between the two valves.

·         Twist the blade until there is a slight pop.

·         Slide the blade upward to cut the adductor muscle which holds the shell closed.

Inexperienced shuckers can apply too much force, which can result in injury if the blade slips. Heavy gloves are necessary; apart from the knife, the shell itself can be razor sharp. Professional shuckers require fewer than three seconds to open the shell.^[32]

If the oyster has a particularly soft shell, the knife can be inserted instead in the 'sidedoor', about halfway along one side where the oyster lips widen with a slight indentation.

Opening or "shucking" oysters has become a competitive sport. Oyster-shucking competitions are staged around the world. Widely acknowledged to be the premiere event, the Guinness World Oyster Opening Championship is held in September at the Galway Oyster Festival. The annual Clarenbridge Oyster Festival 'Oyster Opening Competition' is also held in Galway, Ireland.

 Media related to Oyster-shucking at Wikimedia Commons

Diseases[edit]

Oysters are subject to various diseases which can reduce harvests and severely deplete local populations. Disease control focuses on containing infections and breeding resistant strains, and is the subject of much ongoing research.

·         "Dermo" is caused by a protozoan parasite (Perkinsus marinus). It is a prevalent pathogen, causes massive mortality, and poses a significant economic threat to the oyster industry. The disease is not a direct threat to humans consuming infected oysters.^[56] Dermo first appeared in the Gulf of Mexico in the 1950s, and until 1978 was believed to be caused by a fungus. While it is most serious in warmer waters, it has gradually spread up the east coast of the United States.^[57]

·         Multinucleated sphere X (MSX) is caused by the protozoan Haplosporidium nelsoni, generally seen as a multinucleated Plasmodium. It is infectious and causes heavy mortality in the eastern oyster; survivors, however, develop resistance and can help propagate resistant populations. MSX is associated with high salinity and water temperatures.^[56] MSX was first noted in Delaware Bay in 1957, and is now found all up and down the East Coast of the United States. Evidence suggests it was brought to the US when Crassostrea gigas, a Japanese oyster variety, was introduced to Delaware Bay.^[57]

Some oysters also harbor bacterial species which can cause human disease; of importance is Vibrio vulnificus, which causes gastroenteritis, which is usually self-limiting, and cellulitis. Cellulitis can be so severe and rapidly spreading, often it requires amputation. It is usually acquired when the contents of the oyster come in contact with a cut skin lesion, as when shucking an oyster.

See also[edit]

Wikibooks Cookbook has a recipe/module on ·         Oyster

Food portal

·         Angels on horseback (classic recipe)

·         Auckland oyster

·         Belon oyster

·         Bluff oyster

·         Eastern oyster

·         List of delicacies

·         List of smoked foods

·         Olympia oyster

·         Ostrea angasi (Australian southern mud or native flat oyster)

·         Oyster cracker

·         Oyster farming

·         Oyster festival

·         Oyster omelette

·         Oyster pirate

·         Oyster sauce

·         Oysters Kirkpatrick (classic recipe and minor English literary character)

·         Oysters Rockefeller

·         Pacific oyster

·         Pearl

·         Pearl oyster

·         Red tide

·         Rolled oyster

·         Rock oyster

·         San Leandro Oyster Beds

·         Shellder

·         Sydney rock oyster

·         Tabby (cement)

References[edit]

1.     Jump up^ Oysters in Cynee, Recipe for Oysters in Bread Sauce (Oysters in Cynee) from the 1390 English text, The Forme of Cury, from Celtnet Recipes

2.     Jump up^ ostrea, ostreum, Charlton T. Lewis, Charles Short, A Latin Dictionary, on Perseus

3.     Jump up^ ὄστρεον, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus

4.     Jump up^ ὀστέον, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus

5.     ^ Jump up to:^a b "A dozen ocean-cleaners and a pint of Guinness, please". The Economist. 2008-12-18. Retrieved 2008-12-26.

6.     Jump up^ http://www.worldngayon.com/2011/12/native-oyster-species-in-surigao-del-sur-draws-attention-for-rd/

7.     Jump up^ "Oyster Reefs: Ecological importance" (PDF). US National Oceanic and Atmospheric Administration. Retrieved 2008-01-16.

8.     Jump up^ Tran, D., Nadau, A., Durrieu, G., Ciret, P., Parisot, JP., Massabuau, JC. 2011. Field chronobiology of a Molluscan bivalve: how the moon and sun cycles interact to drive oyster activity rhythms. Chronobiology International, Vol. 28, Num. 4: 307-317.

9.     Jump up^ Ruesink Lab - About the Bay

10.  Jump up^ "China harvests almost 4 m tonnes of oyster in 2005".

11.  Jump up^ Padilla, D.K. 2010. Context-dependent Impacts of a Non-native Ecosystem Engineer, the Pacific Oyster Crassostrea gigas. Integrative and Comparative Biology, Vol. 50, Num. 2: 213-225.

12.  Jump up^ Jud and Layman. 2011. Loxahatchee River oyster reef restoration monitoring report: Using baselines derived from long-term monitoring of benthic community structure on natural oyster reefs to assess the outcome of large-scale oyster reef restoration. Prepared for Martin County, state of Florida.

13.  Jump up^ Jonas, R.B., 1997. Bacteria, dissolved organics and oxygens consumption in salinity stratified Chesapeake Bay, an anoxia paradigm. Am. Zool. 37, 612-620.

14.  Jump up^ Officer, C.B., Smayda, T.J. and Mann, R., 1982. Benthic Filter Feeding - a Natural Eutrophication Control. Mar. Ecol. Prog. Ser. 9, 203-210.

15.  Jump up^ Ulanowicz, R.E. and Tuttle, J.H., 1992. The Trophic Consequences of Oyster Stock Rehabilitation in Chesapeake Bay. Estuaries 15, 298-306.

16.  Jump up^ Newell, R. 2004. Ecosystem Influences of Natural and Cultivated Populations of Suspension-Feeding Bivalve Molluscs: A Review. J. Shellfish Research, 23(1):51-61.

17.  Jump up^ Crisp et al. 1985. Feeding by oyster larvae: the functional response, energy budget and comparison with mussel larvae. J. Marine Biology Assoc. U.K 65:759-783.

18.  Jump up^ "Oyster Restoration Projected to Provide Significant Boost to Bay Grasses While Removing Nitrogen Pollution from the Bay". Maryland Department of Natural Resources. Retrieved 2008-12-26.

19.  Jump up^ Newell, R.I.E., Fisher, T.R., Holyoke, R.R., Cornwell, J.C. (2005). "Influence of eastern oysters on nitrogen and phosphorus regeneration in Chesapeake Bay, USA". In Dame, R., Olenin, S. The Comparative Roles of Suspension Feeders in Ecosystems, Vol. 47 (NATO Science Series IV: Earth and Environmental Sciences ed.). Netherlands: Springer. pp. 93–120.

20.  Jump up^ Grabowski,J.H., Petersen, C.H. (2007). Cuddington, K., Byers, J.E., Wilson, W.G., Hastings, A, ed. Restoring oyster reefs to recover ecosystem services(Ecosystem Engineers: Concepts, Theory and Applications ed.). Amsterdam: Elsevier-Academic Press. pp. 281–298.

21.  Jump up^ Rose JM, Tedesco M, Wikfors GH, Yarish C. (2010). "International Workshop on Bioextractive Technologies for Nutrient Remediation Summary Report". US Dept Commer, Northeast Fish Sci Cent Ref Doc. 10-19; 12 p. Available from: National Marine Fisheries Service, 166 Water Street, Woods Hole, MA 02543-1026.

22.  ^ Jump up to:^a b Brown, Ashton (June 10, 2013). "'Aquaculture' shellfish harvesting bill moves forward". Delaware State News. Retrieved June 11, 2013.

23.  Jump up^ Schulte, David M. et al. 2009. Unprecedented Restoration of a Native Oyster Metapopulation. Science 1124, 325.

24.  ^ Jump up to:^a b Wikfors, Gary H. 2011. Trophic interactions between phytoplankton and bivalve aquaculture. In, Shellfish Aquaculture and the Environment. Ed: S.E. Shumway. John Wiley & Sons.

25.  Jump up^ Officer, C.B., T.J. Smayda & R. Mann. 1982. Benthic filter feeding, a natural eutrophication control. Marine Ecology Progress Series. 9:203-120.

26.  Jump up^ Lindahl, O., et al. 2005. Improving marine water quality by mussel farming- a profitable solution for Swedish society. Ambio 131-138.

27.  Jump up^ Kimbro, D. L. & E. D. Grosholz. 2006. Disturbance influences oyster community richness and evenness, but not diversity. Ecology 87:2378–2388

28.  Jump up^ Camara, M. and Vadopalas, B. 2009. Genetic aspects of restoring Olympia oysters and other native bivalves: Balancing the need for action, good intentions, and the risk of making things worse. Journal of Shellfish Research 28(1):121-145

29.  Jump up^ Jud and Layman. 2011. Loxahatchee River oyster reef restoration monitoring report: Using baselines derived from long-term monitoring of benthic community structure on natural reefs to assess the outcome of large-scale oyster reef restoration.http://www.loxahatcheeriver.org/pdf/FIU_NOAAMonitRpt_2011.pdf

30.  ^ Jump up to:^a b "Oyster industry in NSW". NSW Department of Primary Industries. NSW Government. Retrieved 20 December 2015.

31.  Jump up^ Holland, Tom (2003). Rubicon. ISBN 0-385-50313-X.

32.  ^ Jump up to:^a b c Kurlansky, Mark (2006). The Big Oyster: History on the Half Shell. New York: Ballantine Books. ISBN 978-0-345-47638-8.

33.  Jump up^ Clover, Charles (2004). The End of the Line: How overfishing is changing the world and what we eat. London: Ebury Press. ISBN 0-09-189780-7.

34.  Jump up^ FAO Fisheries & Aquaculture - Aquatic species

35.  Jump up^ "Oyster Farming in Louisiana" (PDF). Louisiana State University. Retrieved 2008-01-16.

36.  Jump up^ Nell J. A. (2002). "Farming triploid oysters". Aquaculture 210: 69–88.doi:10.1016/S0044-8486(01)00861-4.

37.  Jump up^ Conte, Fred S. "California Oyster Culture" (PDF). University of California, Davis Department of Animal Science. Archived from the original (PDF) on 2007-12-01. Retrieved 2008-01-16.

38.  Jump up^ "Shellfish Tenures Locations Map". Retrieved 2008-01-16.

39.  Jump up^ Fountain, Henry (August 3, 2009). "Oysters Are on the Rebound in the Chesapeake Bay". The New York Times. Retrieved August 25, 2009.

40.  Jump up^ http://dirt.asla.org/2011/02/24/oyster-tecture-in-action/

41.  Jump up^ Welcome to BayKeeper

42.  Jump up^ http://www.scapestudio.com/projects/oyster-tecture/

43.  Jump up^ (Bivalve Depuration: fundamental and practical aspects. FAO Fisheries Technical paper. No 511. Rome FAO 2008.)

44.  Jump up^ (Code of Practice for fish and fishery products (first edition) Rome 2009. WHO and FAO ISBN 978-92-5-105914-2)

45.  Jump up^ (Impact of water salinity and types of oysters on depuration for reducing Vibrio parahaemolyticus in Pacific oysters (Crassostrea gigas) Feb 2013 Sureerat Phuvasate, Yi-Cheng Su)

46.  Jump up^ (Escherichia coli in seafood: A brief overview, Renata Albuquerque Costa, Fisheries Engineering, INTA Faculty, Sobral-Ceara, Brazil feb 2013)

47.  Jump up^ Polite Conversations, 1738, cited e.g. in "Oyster Heaven". Wilmington Magazine (Wilmington Star-News). November 24, 2004. Retrieved 2008-01-16.

48.  Jump up^ "Nefsc Fish Faq". Nefsc.noaa.gov. 2011-06-16. Retrieved 2011-08-16.

49.  Jump up^ "Nutrition Facts and Analysis for Mollusks, oyster, eastern, wild, raw". Nutritiondata.com. Retrieved 2011-08-16.

50.  Jump up^ "Calories in pacific Oyster". Recipeofhealth.com. 2015-03-28.

51.  Jump up^ Stott, Rebecca (2004). Oyster. The University of Chicago Press.ISBN 9781861892218. Retrieved 2008-01-16.

52.  Jump up^ "Pearly wisdom: oysters are an aphrodisiac". The Sydney Morning Herald. 2005-03-24.

53.  Jump up^ "Safely Cooking Oysters and Other Molluscan Shellfish". SafeOysters.org. 2009-03-09. Retrieved 2015-06-13.

54.  Jump up^ "Mussel myth an open and shut case". ABC Science. 2008-10-29. Retrieved 2012-04-20.

55.  Jump up^ "Fried Oyster". Best Malaysian Food Guide. Retrieved 24 July 2015.

56.  ^ Jump up to:^a b "Oyster Diseases". Connecticut Department of Agriculture. Retrieved2008-01-16. External link in |publisher= (help)

57.  ^ Jump up to:^a b "MSX/Dermo". Chesapeake Bay Program. Retrieved 2009-04-05.External link in |publisher= (help)

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همچنین:

عرق اللؤلؤ (بالإنجليزية: Nacre) المعروف أيضاً باسم أم اللؤلؤ، و هو عبارة عن مجموعة من المواد العضوية، وغير العضوية المركبة التي تنتجها بعض الرخويات باعتبارها طبقة قشرة داخلية، وهي أيضاً ما يتكون منها اللؤلؤ. تركيبته قوية جداً ومرنة، وقزحي اللون.

قشرة الصدف قزحي الألوان.

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·         بوابة علم الأحجار الكريمة والمجوهرات

هذه بذرة مقالة بحاجة للتوسيع. شارك في تحريرها.

في كومنز صور وملفات عن: عرق اللؤلؤ

تصنيفات: 

·         لؤلؤ

·         مجوهرات

·         أحجار كريمة

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به عبری:

אם הפנינה או דַּר או צִדְפַּת הַפְּנִינִים היא חומר מרוכב אורגני ולא אורגני המיוצר על ידי מספר רכיכות.

אם פנינה ססגונית של קונכיית הנאוטילוס

אם הפנינה היא גמישה, חזקה וססגונית. פנינים והרבדים הפנימיים של קליפת הצדפות נעשות מחומר זה.

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به ترکی  صِدِف:

Sedef, midye ve istiridye gibi deniz hayvanlarının kabuğunda bulunan süslemecilikte kullanılan, pırıltılı, beyaz, sert bir maddedir. 10-20 mikrometre genişliğinde ve 0,5 mikrometre kalınlığında CaCO₃ plakaların birleşmesinden meydana gelen sedef kompozit bir malzemedir. İstanbul, Kudüs ve Viyana gibi merkezlerde, çeşitli zamanlarda süsleme amaçlı kullanılmıştır.

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Nacre (/ˈneɪkər/ nay-kər also /ˈnækrə/ nak-rə),^[1] also known as mother of pearl, is an organic-inorganic composite material produced by some molluscs as an inner shell layer; it also makes up the outer coating of pearls. It is strong, resilient, and iridescent.

Nacre is found in some of the more ancient lineages of bivalves, gastropods, and cephalopods. However, the inner layer in the great majority of mollusc shells is porcellaneous, not nacreous, and this usually results in a non-iridescent shine, or more rarely in non-nacreous iridescence such as flame structure as is found in conch pearls.

The outer layer of pearls and the inside layer of pearl oyster and freshwater pearl mussel shells are made of nacre. Other mollusc families that have a nacreous inner shell layer include marine gastropods such as the Haliotidae, theTrochidae and the Turbinidae.

Contents

  [show] 

Physical characteristics[edit]

Structure and appearance[edit]

Further information: Structural coloration

Schematic of the microscopic structure of nacre layers

Electron microscopy image of a fractured surface of nacre

Nacre is composed of hexagonal platelets of aragonite (a form of calcium carbonate) 10–20 µm wide and 0.5 µm thick arranged in a continuous parallel lamina.^[2] These layers are separated by sheets of organic matrix composed of elastic biopolymers (such aschitin, lustrin and silk-like proteins). This mixture of brittle platelets and the thin layers of elastic biopolymers makes the material strong and resilient, with a Young's modulus of 70 GPa (when dry).^[3] Strength and resilience are also likely to be due to adhesion by the "brickwork" arrangement of the platelets, which inhibits transverse crack propagation. This structure, at multiple length sizes, greatly increases its toughness, making it almost as strong as silicon.

Nacre appears iridescent because the thickness of the aragonite platelets is close to the wavelength of visible light. These structures interfere constructively and destructively with different wavelengths of light at different viewing angles, creating structural colours.

The crystallographic c-axis points approximately perpendicular to the shell wall, but the direction of the other axes varies between groups. Adjacent tablets have been shown to have dramatically different c-axis orientation, generally randomly oriented within ~20° of vertical.^[4][5] In bivalves and cephalopods, the b-axis points in the direction of shell growth, whereas in the monoplacophora it is the a-axis that is this way inclined.^[6] The interlocking of bricks of nacre has large impact on both the deformation mechanism as well as its toughness.^[7] In addition, the mineral–organic interface results in enhanced resilience and strength of the organic interlayers.^[8][9][10]

Formation[edit]

Nacre formation is not fully understood. The initial onset assembly, as observed in Pina nobilis, is driven by the aggregation of nanoparticles (~50–80 nm) within an organic matrix that arrange in fibre-like polycrystalline configurations.^[11] The particle number increases successively and, when critical packing is reached, they merge into early-nacre platelets. Nacre growth is mediated by organics, controlling the onset, duration and form of crystal growth.^[12] Individual aragonite "bricks" are believed to quickly grow to the full height of the nacreous layer, and expand until they abut adjacent bricks.^[6] This produces the hexagonal close-packing characteristic of nacre.^[6]Bricks may nucleate on randomly dispersed elements within the organic layer,^[13] well-defined arrangements of proteins,^[2] or may grow epitaxially from mineral bridges extending from the underlying tablet.^[14][15] Nacre differs from fibrous aragonite – a brittle mineral of the same form – in that the growth in the c-axis (i.e., approximately perpendicular to the shell, in nacre) is slow in nacre, and fast in fibrous aragonite.^[16]

Function[edit]

Fossil nautiloid shell with original iridescent nacre in fossiliferous asphaltic limestone, Oklahoma. Dated to the late Middle Pennsylvanian, which makes it - by far - the oldest deposit in the world with aragonitic nacreous shelly fossils.^[17]

Nacre is secreted by the epithelial cells of the mantle tissue of various molluscs. The nacre is continuously deposited onto the inner surface of the shell, the iridescent nacreous layer, commonly known as mother of pearl. The layers of nacre smooth the shell surface and help defend the soft tissues against parasites and damaging debris by entombing them in successive layers of nacre, forming either a blister pearl attached to the interior of the shell, or a free pearl within the mantle tissues. The process is called encystation and it continues as long as the mollusc lives.

In different mollusc groups[edit]

Further information: Mollusc shell § Evolution

The form of nacre varies from group to group. In bivalves, the nacre layer is formed of single crystals in ahexagonal close packing. In gastropods, crystals are twinned, and in cephalopods, they are pseudohexagonal monocrystals, which are often twinned.^[6]

Commercial sources[edit]

The main commercial sources of mother of pearl have been the pearl oyster, freshwater pearl mussels, and to a lesser extent the abalone, popular for their sturdiness and beauty in the latter half of the 19th century.

Widely used for pearl buttons especially during the 1900s, were the shells of the great green turban snail Turbo marmoratus and the large top snail, Tectus niloticus. The international trade in mother of pearl is governed by theConvention on International Trade in Endangered Species of Wild Fauna and Flora, an agreement signed by more than 170 countries.^[18]

Decorative uses[edit]

·         Nacre has been used for centuries for a variety of decorative purposes

·        

Altarpiece, circa 1520, with extensive use of carved nacre.

·        

Nacre gunpowder flask, circa 1750, mostly consisting of the polished shell of a large sea snail Turbo marmoratus.

·        

Inlay with nacre tesserae, Baghdad pavilion, Topkapı Palace, Istanbul.

·        

Nacreous shell worked into a decorative object.

·        

Nacre pendant engraved Solomon Islands1838

Architecture[edit]

White nacre mosaic tiles in the ceiling of the Criterion Restaurant in London

Both black and white nacre are used for architectural purposes. The natural nacre may be artificially tinted to almost any color. Nacre tesserae may be cut into shapes and laminated to a ceramic tile or marble 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 about 2 millimetres (0.079 in) thick. The tesserae are then lacquered and polishedcreating a durable and glossy surface.

Instead of using a marble or tile base, the nacre tesserae can be glued to fiberglass. The result is a lightweight material that offers a seamless installation and there is no limit to the sheet size. Nacre 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.^{[citation needed]}

Fashion[edit]

Nacre bracelet

Mother of pearl buttons are used in clothing either for functional or decorative purposes. The Pearly Kings and Queens are an elaborate example of this.

Nacre is also used to decorate watches, knives, guns and jewellery.

Musical instruments[edit]

Nacre inlay is often used for music keys and other decorative motifs on musical instruments. Many accordion andconcertina bodies are completely covered in nacre, and some guitars have fingerboard or headstock inlays made of nacre (as well as some guitars having plastic inlays designed to imitate the appearance of nacre). The bouzoukiand baglamas (Greek plucked string instruments of the lute family) typically feature nacre decorations, as does the related Middle Eastern oud (typically around the sound holes and on the back of the instrument). Bows of stringed instruments such as the violin and cello often have mother of pearl inlay at the frog. It is traditionally used in the valve buttons of trumpets and other brass instruments as well.

Other[edit]

Mother of pearl is sometimes used to make spoon-like utensils for caviar, so as to not spoil the taste with metallic spoons.

Manufactured nacre[edit]

In 2012, researchers created calcium-based nacre in the laboratory by mimicking its natural growth process.^[19]

In 2014, researchers used lasers to create an analogue of nacre by engraving networks of wavy 3D "micro-cracks" in glass. When the slides were subjected to an impact, the micro-cracks absorbed and dispersed the energy, keeping the glass from shattering. Altogether, treated glass was reportedly 200 times tougher than untreated glass.^[20]

See also[edit]

·         Ammolite

·         Mollusc shell

·         Pearl

·         Raden

References[edit]

1.     Jump up^ Definition of nacre at dictionary.com.

2.     ^ Jump up to:^a b Nudelman, Fabio; Gotliv, Bat Ami; Addadi, Lia; Weiner, Steve (2006). "Mollusk shell formation: Mapping the distribution of organic matrix components underlying a single aragonitic tablet in nacre". Journal of Structural Biology 153 (2): 176–87. doi:10.1016/j.jsb.2005.09.009.PMID 16413789.

3.     Jump up^ Jackson, A. P.; Vincent, J. F. V; Turner, R. M. (1988). "The mechanical design of nacre". Proceedings of the Royal Society B: Biological Studies(The Royal Society, published 22 Sep 1988) 234 (1277): 415–440.doi:10.1098/rspb.1988.0056. JSTOR 36211. Retrieved 2013-11-12.

4.     Jump up^ Metzler, Rebecca; Abrecht, Mike; Olabisi, Ronke; Ariosa, Daniel; Johnson, Christopher; Frazer, Bradley; Coppersmith, Susan; Gilbert, PUPA (2007). "Architecture of columnar nacre, and implications for its formation mechanism".Physical Review Letters 98 (26): 268102.doi:10.1103/PhysRevLett.98.268102. PMID 17678131.

5.     Jump up^ Olson, Ian; Kozdon, Reinhard; Valley, John; Gilbert, PUPA (2012). "Mollusk shell nacre ultrastructure correlates with environmental temperature and pressure". Journal of the American Chemical Society 134 (17): 7351–7358.doi:10.1021/ja210808s. PMID 22313180.

6.     ^ Jump up to:^a b c d Checa, Antonio G.; Ramírez-Rico, Joaquín; González-Segura, Alicia; Sánchez-Navas, Antonio (2008). "Nacre and false nacre (foliated aragonite) in extant monoplacophorans (=Tryblidiida: Mollusca)". Naturwissenschaften 96(1): 111–22. doi:10.1007/s00114-008-0461-1. PMID 18843476.

7.     Jump up^ Katti, Kalpana S.; Katti, Dinesh R.; Pradhan, Shashindra M.; Bhosle, Arundhati (2005). "Platelet interlocks are the key to toughness and strength in nacre". Journal of Materials Research 20 (5): 1097.doi:10.1557/JMR.2005.0171.

8.     Jump up^ Ghosh, Pijush; Katti, Dinesh R.; Katti, Kalpana S. (2008). "Mineral and Protein-Bound Water and Latching Action Control Mechanical Behavior at Protein-Mineral Interfaces in Biological Nanocomposites". Journal of Nanomaterials 2008: 1. doi:10.1155/2008/582973.

9.     Jump up^ Mohanty, Bedabibhas; Katti, Kalpana S.; Katti, Dinesh R. (2008). "Experimental investigation of nanomechanics of the mineral-protein interface in nacre". Mechanics Research Communications 35: 17.doi:10.1016/j.mechrescom.2007.09.006.

10.  Jump up^ Ghosh, Pijush; Katti, Dinesh R.; Katti, Kalpana S. (2007). "Mineral Proximity Influences Mechanical Response of Proteins in Biological Mineral−Protein Hybrid Systems". Biomacromolecules 8 (3): 851–6. doi:10.1021/bm060942h.PMID 17315945.

11.  Jump up^ Hovden, Robert; Wolf, Stephan; Marin, Frédéric; Holtz, Meganc; Muller, David; Lara, Estroff (2015). "Nanoscale assembly processes revealed in the nacroprismatic transition zone of Pinna nobilis mollusc shells". Nature Communications 6: 10097. doi:10.1038/ncomms10097.

12.  Jump up^ Jackson, D. J.; McDougall, C.; Woodcroft, B.; Moase, P.; Rose, R. A.; Kube, M.; Reinhardt, R.; Rokhsar, D. S.; et al. (2009). "Parallel Evolution of Nacre Building Gene Sets in Molluscs". Molecular Biology and Evolution 27 (3): 591–608. doi:10.1093/molbev/msp278. PMID 19915030.

13.  Jump up^ Addadi, Lia; Joester, Derk; Nudelman, Fabio; Weiner, Steve (2006). "Mollusk Shell Formation: A Source of New Concepts for Understanding Biomineralization Processes". ChemInform 37 (16).doi:10.1002/chin.200616269.

14.  Jump up^ Schäffer, Tilman; Ionescu-Zanetti, Cristian; Proksch, Roger; Fritz, Monika; Walters, Deron; Almquist, Nils; Zaremba, Charlotte; Belcher, Angela; Smith, Bettye; Stucky, Galen (1997). "Does abalone nacre form by heteroepitaxial nucleation or by growth through mineral bridges?". Chemistry of Materials 9(8): 1731–1740. doi:10.1021/cm960429i.

15.  Jump up^ Checa, Antonio; Cartwright, Julyan; Willinger, Marc-Georg (2011). "Mineral bridges in nacre". Journal of Structural Biology 176 (3): 330–339.doi:10.1016/j.jsb.2011.09.011. PMID 21982842.

16.  Jump up^ Bruce Runnegar & S Bengtson. "1.4". Origin of Hard Parts — Early Skeletal Fossils (PDF).

17.  Jump up^ Buckhorn Lagerstätte of Oklahoma Click on photo for more information.

18.  Jump up^ Jessica Hodin, "Contraband Chic: Mother-of-Pearl Items Sell With Export Restrictions", New York Observer, October 20, 2010

19.  Jump up^ Aron, Jacob (24 July 2012). "Artificial mother of pearl follows nature's recipe". New Scientist.

20.  Jump up^ "Super-tough glass based on mollusk shells". Gizmag.com. Retrieved2014-02-13.

Further reading[edit]

·         Frýda, J.; Bandel, K.; Frýdová, B. (2009). "Crystallographic texture of Late Triassic gastropod nacre: evidence of long-term stability of the mechanism controlling its formation". Bulletin of Geosciences 84 (4): 745–754. doi:10.3140/bull.geosci.1169.

·         Lin, A.; Meyers, M.A. (2005-01-15). "Growth and structure in abalone shell". Materials Science and Engineering A 390 (1–2): 27–41.doi:10.1016/j.msea.2004.06.072.

·         Mayer, G. (2005). "Rigid biological systems as models for synthetic composites". Science 310 (5751): 1144–1147. doi:10.1126/science.1116994.PMID 16293751.

·         Bruet, B.; Qi, H.J.; Boyce, M.C.; Panas, R.; Tai, K.; Frick, L.; Ortiz, C. (2005). "Nanoscale morphology and indentation of individual nacre tablets from the gastropod mollusc Trochus niloticus" (PDF). J. Mater. Res. 20 (9): 2400. doi:10.1557/JMR.2005.0273.

·         Antonio G. Checa, Julyan H. E. Cartwright, Marc-Georg Willinger and Steven M. Stanley, The Key Role of the Surface Membrane in Why Gastropod Nacre Grows in Towers; Proceedings of the National Academy of Sciences of the United States of America, Vol. 106, No. 1, Jan. 6, 2009