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An in-depth understanding of pearl formation, the role of molluscs, and the process of pearl culture. It covers the introduction to pearls, pearl formation, culture of pearls, and collection of oysters. Important pearl-bearing species are also discussed. useful for students of marine biology, zoology, and environmental sciences.
Typology: Exercises
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By,Dr. Purnima Das Bora Associate ProfessorDhing College
Pearl is a concretion formed by molluscs. It consists of nacre or mother of pearl. The nacre is formed of two substances , namely a calcium carbonate which is in the form of argonite or calcite and an albuminoid substance called conchiolin. Kokichi Mikimoto of Toba ( Japan ) is known to be the father of pearl industry. He discovered a method to
induce foreign particle between the mantle and the shell of the pearl oyester and thus stimulated pearl formation.
Fig. 1 : Pinctada vulgaris
Pearl formation :- The pearl of oysters produce pearl as an adaptation against outside material. When a foreign material enter the body such as a particle of sand or a small parasite , it adheres with the mantle. The mantle epithelium starts secreting concentric layers of nacre around the foreign material. The completed structure is called pearl.
Most precious oysters are found in pearl oysters of the genus Pinctada. Important species for pearls are P. vulgaris , P. chemnitzi , P. margaritifera , P. anomioides and
Collection of Oysters : Oysters for pearl culture are obtained by three methods. They are as follows :
Preparation of Nucleus :
The nucleus is a foreign material which is inserted into the oyster. It in the form of a bead of 2 mm in diameter. It is prepared from the shell of molluscs.
Implantation : The oyster is placed on a table. The foot is exposed. A small incision is made on the foot.
On this incision the graft tissue is placed. Then the oyster is released in cages. The entire operation should be completed in 30 minutes.
Rearing of Oysters : The operated oysters are placed in cages and the cages are suspended from rafts in the sea
. This type of culturing oysters is called raft culture.
Harvesting :
