This document summarizes the process of pearl formation. It begins by introducing pearls as a round concretion produced biologically by molluscs. Pearls form when a foreign object or nucleus becomes enclosed in nacreous material secreted by the mollusc. The document then describes the multi-layered structure of mollusc shells. It discusses natural and artificial pearl production methods and the chemical composition and quality assessment of pearls. Key stages in pearl formation like nucleus insertion and convalescence are outlined. Finally, the document lists common pearl-producing mollusc species and their distribution.

1. KUNAL
17373016
MSc. 1ST Year
Taxonomy of marine organisms
Dr. T. GANESH
SUBMITTED TO SUBMITTED BY
PEARL FORMATION

2. INTRODUCTION
 IT IS ALSO KNOWN AS “MOTI”.
 A ROUND CONCRETION OF SKELETAL MATERIAL.
 BIOCHEMICAL PRODUCT OF MOLLUSC.
 ONLY GEM PRODUCED BY THE LIVING ANIMALS.
 HIGHLY SHINING GLOBULAR IN SHAPE.
 PEARL CONSISTS OF A CENTRAL NUCLEUS SURROUNDED BY A SERIES OF
PEARLY NACREOUS MATTER.
 NACRE/MOTHER-OF-PEARL IS A SHINY,HARD PEARLY IRIDESCENT SUBSTANCE
FORMING THE INNER LAYER OF A MOLLUSC SHELL.
 SHELL CONSISTS OF 3LAYERS, NAMELY AN OUTER ORGANIC LAYER OF
CONCHIN AND TWO INNER CALCAREOUS LAYERS

3. PRODUCTION OF PEARLS
NATURAL WAY
NATURAL PEARLS ARE FORMED
DUE TO NATURAL PROCESSES OR
DISTURBANCES IN THE
ENVIRONMEN WHERE THE OYSTER
LIVES.
ARTIFICIAL WAY
ARTIFICIALLY INDUCING THE
MOLLUSC TO SECRETE NACREOUS
MATTER AROUND AN INSERTED
NUCLEUS. IT IS PRODUCED BY
HUMAN INTERFERENCE AND IS
KNOWN AS CULTURED PEARL. CHIEF
IMITATIONS MADE OF PLASTICS
THAT HAVE A ARTIFICIAL LUSTRE ARE
KNOWN AS ARTIFICIAL PEARL.

4. CHEMICAL COMPOSITION OF PEARL
1.WATER - 3.97%
2.ORGANIC MATTER - 3.83%
3.ALCITE & ARAGONITE - 91.53%
4.LOSS - 0.67%
QUALITY OF PEARL IS DETERMINED BY ITS KERATIN CONTENT AND COLOR. THE
LATTER IS INFLUENCED BY THE COLOR OF THE SHELL OF DONOR MOLLUSCFROM
WHICH PALLIUM (Graft-tissue) HAD BEEN TAKEN AND THE PART FROM WHERE
IT IS EXTRACTED AND IMPLANTED.

5. PEARL OYSTERS AND THEIR DISTRIBUTION
1. Pinctada anomioides –Bombay, Madras Harbour, Andaman.
2. P. atropurpurea – Madras Harbour, Andaman.
3. P. chemnitzi - Madras Harbour, Palk Bay.
4. P. fucata – Common indian pearl oyster, Gulf of Kachch.
5. P. margaritifera – Common in Andaman and Nicobar.
6. P. sugillata – Gujarat, Tuticorin, Andaman.

6. STAGES IN THE PEARL FORMATION
1. PREPARATION OF HOST SHELL
2. NUCLEUS INSERTION
3. CONVALESCENCE
5.HARVESTING
6.PROCESSING OF PEARLS
4. PEARL FORMATION  Fig. Removing the oysters from
their shell.

7. PREPARATION OF HOST SHELL
 IN NATURE PEARLS MAY BE FORMED IN DIFFERENT REGIONS OF THE BODY NAMELY THE REGION OF ADDUCTOR
MUSCLES, MANTLE MARGIN, PALLIAL ZONE.
 THE BEST SITE FOR PEARL PRODUCTION IS CONSIDERED TO BE THE GONADIAL REGION,SPENT INDIVIDUALS
(individuals whose gonads are devoid of gametes) SERVES AS GOOD HOSTS.
 NUCLEUS IS INSERTED IN THE GONADIAL REGION.

8. NUCLEUS INSERTION
 IT INVOLVES SELECTION OF A SUITABLE DONOR SHELL OR ANY OTHER OBJECT FOR OBTAINING THE NUCLEAR
MATERIAL AND DONOR OYSTER OR MUSSEL FOR OBTAINING GRAFT TISSUE.
 THE SIZE OF THE NUCLEUS DETERMINES THE SIZE OF THE GRAFT TISSUE.
 AFTER OBTAINING THE NUCLEUS AND GRAFT TISSUE THE RECIPIENT OYSTER WILL BE OPERATED UPON AND THE
NUCLEUS IS IMPLANTED IN THE GONADIAL REGION.
 THE TIME AND NUMBER OF NUCLEI TO BE IMPLANTED WILL BE DETERMINED IN ADVANCE.

9. CONVALESCENCE (PERIOD OF TIME SPENT HEALING)
 AFTER OPERATION THE MUSSEL ARE ALLOWED TO BE RECOVER FROM THE DISTURBANCE CAUSED.
 THE OYESTER ARE KEPT IN CAGES.
PEARL FORMATION
 THE GRAFT TISSUE ON THE NUCLEUS GROWS INTO A PEARL SAC.
 THE EPITHELIAL CELLS OF THE PEARL SAC DEPOSIT NACREOUS LAYER AROUND THE NUCLEUS, WHICH ULTIMATELY
LEADS TO THE FORMATION PF A PEARL.
 IN PEARL OYSTERS IT TAKES TO 3-4 YEARS OF COMMERCIAL VALUE TO DEVELOP.
 IN FRESHWATER MUSSEL PEARLS ARE HARVESTED 2-3 YEARS AFTER IMPLANTATION.

10. HARVESTING
 OYESTERS OR MUSSELS WITH PEARLS ARE
BROUGHT TO THE LABORATORY. THE VALVES
ARE OPENED AND THE FLESHY PARTS ARE
EXTRACTED OUT. THE PEARLS ARE
OBTAINED BY PULVERISING THE EXTRACTED
PART.
PROCESSING OF PEARLS
 SOON AFTER THEIR SEPARATION FROM THE MEAT, PEARLS ARE WASHED WITH WATER TO
REMOVE THE MUCILAGINOUS MATTER AND MAINTAIN THE LUSTER. THE PEARLS ARE THEN
GRADED ACCORDING TO SIZE.

11. REFERENCEs
1.N.V. Subba Rao.,Records of the Zoological Survey of india, Indian seashells
2.Rebecca stott, Oyster
3.R.L. Kotpal, Invertebrates zoology
4. www.google.com