culture practices of pearl is discussed

2.  What is pearl and pearl culture?
 History of pearl culture
 Types of pearl culture
 Pearl producing molluscs
 Basic structure of pearl formation
 Pearl culture technique
 Composition of pearl
 Enemies of pearl culture
 Economic importance of pearl and pearl culture

3. PEARL(MOTI):- Pearl is a highly shining and precious
gem that is formed inside the shell of certain molluscs
(Oysters).
PEARLCULTURE:-
• ‘The rearing of bivalve molluscs in a controlled conditions
for obtained a pearl’.
• The bivalve molluscs are two different groups- the
freshwater and saltwater oysters.
• Pearls are formed inside the shell of certain molluscs as a
defence mechanism against a potentially threatening
irritant(parasite and injury of mantle tissue).
PEARL and PEARL CULTURE

4. The pearl culture technique was first initiated in Japan.
Father of Pearl culture- Kokichi Mikimoto (1858-1954),
Mikimoto was established a pearl farm in Toba (small island in Japan ).
He got pearl in July 1893 in his farm. In 1896, he did pearl patents.
Best quality pearl is called Lingha Pearl.
In India, the technological breakthrough in pearl culture was achieved in 1973 by the Central
Marine fisheries research institute(CMFRI-Kochi, Kerala) at Tuticorin, Tamil Nadu.
Pearl Oyster Fisheries In India: Two Main Areas
1. The Gulf of Mannar of Tuticorin coast (Tamil-Nadu) and
2. The Gulf of Kutch (Gujarat).

5. • Three types of pearl:
1.Natural Pearl: may be formed within the oyster or
mussels by either accidental entrance of a solid or
accidental wound with in the shell tissues. This type of
pearl is very rare.
2.Cultured Pearl: are produced by human
interference.
3.Artificial Pearl: these are made up of plastic, glass,
and fish scales.

6. • All bivalve oysters can make a pearl.
• But for economic purposes, only some oyster species are used.
Sl.no. Species Common Name Remarks
1 Pinctada margaritifera Black-lip pearl oyster Best pearl
2 Pinctada fucata Akoya pearl oyster Pinctada vulgaris- Indian pearl oyster (India)
Pinctada martensii (Japan )
3 Placuna maxima Gold-lip or silver-lip pearl
oyster
4 Pinctada atropurpurea Fragile pearl shell oyster
5 Pferia penguin Penguin wing oyster

7. Sl.no. Species Common name Remarks
6 Tridacna gigas Giant Clam (Natural) Large size pearl
7 Lamellidens marginalis In India and South Asia is
used.
Freshwater pearl
8 Lamellidens corrianus In India Fresh water mussels
 Other genus: Haliothis, and Mytilus (Low quality pearl).

8. Kingdom: Animalia
Phylum: Mollusca
Class: Bivalvia
Order:Pteriida
Family: Pteriidae
Genus: Pinctada

9. • Two part are found in an Oyster:
1. Shell and
2. Mantle
▪ Mantle: In Bivalve, Mantle layer present just below to Shell, in which
outer most layer is columnar epithelium cells (this layer contains Nacre
secreting unicellular cells that form Pearl).
▪ Connecting tissue found below to outer layer and innermost layer is
formed by ciliated epithelium cells (secretion of Mucous).
 Shell: Shell made up of 03 layers
1. Peri-ostracum:
2. Prismatic Layer:
3. Nacreous Layer:

10. 1. Peri-ostracum: Outermost layer of shell which is made
up of organic substance (Conchiolin- a protein).
 It work as a protective layer.
 It's formed by epithelium cells in the larval stage and in
the adult stage is formed by the edges of the mantle.
2. Prismatic Layer: It is the middle layer secreted by
mantle. These crystals are arranged perpendicular to the
shell surface. It gives strength and rigidity to the shell.
3. Nacreous Laver: Innermost layer of Shell. This is made
up of Calcium carbonate and arranged in parallel form.
This layer is called 'Mother of Peral’. Form by secretion of
Epithelium ceIls of Mantle.

11.  Pearl is formed due to secretion of mantle part in response
to irritations caused by foreign particles (parasite, soil,
Marine algae, piece of grass, and micro insect).
 The Pearl attached with mantle.
 Mantle epithelium cells secreted calcium carbonate
surround to it and form many layer.
 This structure is will be made a
Pearl after dry.

12.  Pearl formation is a complex and technical process.
 Pearl culture is done by trained and specialists.
 Cultivation or culture of pearl is in controlled conditions.
Whole process is divided in to following steps:
1. Collection of Oysters:
2. Insertion of Nucleus:
3. Post operational care of Oysters:
4. Harvesting of Pearls:

13. Collection of oysters
rearing of oysters
selection of oysters
preparation of nuclear shell beads
preparation of graft tissue
insertion of nucleus
nursing the oyster
harvesting

14. 1. COLLECTION OF OYSTERS:
 This is first step. Spats (young one oysters) are collected from spat-falling areas.
 Oysters are reared in marine water and fresh water bodies.
 The divers, collect the oysters to the bottom of the sea.
 Collection of oysters shall be done from July to
November due to spats are easily available.
 These collected oysters are now transferred to rearing
cages.
 The young ones are reared until they are mature enough
to undergo the grafting procedure.
 Rearing cages are suspended in the sea at a depth of
6- meters.

15. 2. INSERTION OF NUCLEUS:
This process is fully technical.
 Nucleus is a special structure that will be inserted in to
mantle part of oysters.
 After the insertion of nucleus in to an oyster, nacre
layer will be start for secretion.
 The shape of pearl is depend on the graft that is inserted.
 For insertion of nucleus, Nishikawa method is used- (A healthy oyster will be put into hot and
warm water in an alternate, so the shell will be opened).
 Reproductive organs also removed.

16. 2. INSERTION OF NUCLEUS:
 The oyster is opened with special wedges and
pliers, then a scalpel slit is made in the soft tissue
near the reproductive organ.
 The graft (1-2) is inserted into mantle.
 Insertion process of nucleus will be completed
with in 3 minutes).
 Oysters that accepted the implanted are
transferred to the pearl farm.

17. 3.POST OPERATIONAL CARE OF OYSTER:
 The oysters are transferred to the pearl farm where
they are rearing baskets or cages that attached to
long lines connected to the floating rafts.
 The rafts are dropped down 2-3 meter into the water
just after the nucleus insertion.
 With in 6-7 days, the wound will be filled, so rearing
cages take out from water and check (dead oyster will be removed). Then it must be 14 meter
depth in ocean.
 Regular cleaning of the shells to remove seaweed results in better pearls.
 The cleaning is done by a machine which uses water jets and brushes to clean off any seaweed.

18. 4. HARVESTING OF PEARLS:
 The whole process of pearl culture taken 03-06
years.
 The harvesting process shall be done from
December to January month or it depends on
the weather.
 For obtained Peral, the oyster two shell valves
must be opened (cutting the adductor muscle, making an incision on the gonad)
and then push out the pearl by pressure.
 Finally, the harvested pearls are washed in distilled water, polished with refined salt
and sorted for sale according to size, colour, shape, lustre and other external
characteristics.

19. • Pearl consists of water, organic matter, calcium carbonate and
the residue.
1. Calcium carbonate: 85-90%
2. Organic matter (Conchiolin protein): 05-07%
3. Water: 02-04%
4. Residue: 0.1-0.8%

20.  Boringorganisms:
• Boring organisms comprising polychaetes, sponges, molluscs and isopods (crustaceans) may cause
considerable damage to the pearl oyster shell.
 Predator organisms:
• Predators in wild beds are mainly benthic fish which feed on young oysters below one year of age,
while rays, octopods and starfish feed on adult oysters.
• Cymatium cingulatum and Murex virgeneus have been found to be serious predators in natural
oyster beds.
• Usually in the culture sites crabs are the worst predators.
 Biofouling:
• Barnacles: The cirriped Balanus amphitrite is one of the major fouling organism. Heavy
settlement of barnacles cause physical obstruction to the opening and closing of the oyster valves.
• Ascidians, Bryozoans, Molluses, Sponges and other organisms such as amphipods, hydroids algae,
anthozoans, crabs, tubicolous polychaetes, Pycnogonids, and polyclad worms.
Enemies of pearl culture

21.  Used as an ornament and a symbol of grandeur.
 Used in ornamental handicraft.
 By-Products of Pearl: The by-products of pearl culture are seed pearls, shell and
flesh.
 Medicinal values (tiny seed pearls which are unsuitable as a gem) are used as:
 Use as Laxative, sedative, emetic and nutrition.
 Pearl powders act as an antacid.
 It is also used in heartburn and bilious affections.
 The pearl is used in formation of calcium tablets, and in allergic rection
treatment.
 Large oyster shells are used in shell craft.
 Small and broken shells of oysters are used as food ingredients in poultry.
 The flesh of oysters is used for human consumption and feeding fishes.

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