PG Department of Zoology
SD Degree College mzn
M.Sc. Zoology 2022-23
Topic – Pearl Culture
Presented by:
Raina baliyan

Content
• What is pearl and pearl culture
• Types of pearl
• Pearl producing mollusc
• Basic structure of pearl formation
• Pearl culture technique
• Composition of pearl
• Economic importance of pearl and
pearl Culture

• Pearl and pearl culture
• Pearl- pearl is highly shining and
precious gem that is formed inside the
shell of certain mollusc (oyster)
• Pearl culture- pearl are formed inside
the shell of certain mollusc as à
defence mechanism against à
potentially threatening irritant
(parasitic and injury) .

Types of pearl
• Natural pearl- natural pearl may be found within oyster Or
mussels by either accidental entrance of à solid Or accident
wound within the shell tissue this type of pearl is very rare
• Cultured pearl- cultured pearl are produced by human
interference.
• Artificial pearl- these are made up of plastic , glass and fish
scales

Pearl producing Molluscs
• All bivalve oyster can make pearl
• But for economic purpuse only some oyster are used
• Pictada margaritifera – best pearl producing mollusca
• Pintada fucata – pinctada vulgaris indian pearl oyster
• Pinctada maxima

Basic structure of pearl formation
• Two part are found in oyster
1. Shell shell is made up of 3 layers
• Peri ostracum –calchiolin
• Prismatic layer –provide strength and rigidity
• Nacreous layer –calcium carbonate
(Mother of pearl) formed by inner epithillim.
2.Mantle is bivalve layer present just below to the shell in which
outer most layer is columnar epithelial cells ( this layer contain
nacre secreting mollusc cell that form pearl.

Pearl formation
• Pearl is formed due to secretion of mantle part in response to irritation by
foreign parasite, soil, marine algae, piece of grass and Micro insect.
• The pearl attached with mentle
• Mantle epithilum secreted calcium carbonate surround to it and form layer
• This structure is will made a pearl after dry

Pearl culture technique
• Pearl culture is done by trained and specialist. It involve
cultivation Or culture of pearl is in controlled condition.
• Process divided into following step
1. Collection of oyster ।
Spats are collected from spat falling areas. Oyster are reared in
marine water and fresh water bodies. The divers collection the
oyster shell be done from july to november due to spat are easily
available.
These collected oyster are now transferred to rearing cages and
reared untill they mature enough to undergo the grafting . Rearing
cage are suspended in the deapth of 6 mtr.

Pearl culture technique
• Insertion of nucleus:
• insertion of nucleus in the oyster, nacre layer will Be
start for secretion.
• The shape of the pearl depand on the graft that is inserted
• Nishikawa method is used –
• Reporductive organ are removed
• The oyster is opened with spécial wedges and plier then à
scalped slit is made in the soft tissue near the reproductive
organisation and graft is inserted and then tranfered to the
pearl farm.

Pearl culture technique
• Post operational care of oyster
• The rearing basket Or cages are attached to
long lines connected to floating raft and
draped down
• With in 6-7 days the wound will Be filled so
rearing cages take out from water and check.
Dead Were removerd and then it must Be 14
mtr in depth of sea
• Cleaning is done by machines

Pearl culture technique
• Harvesting of pearl
• Harvesting process shall Be done from déc to
jan month Or it depend on the weather.
• For obtained pearl the oyster two shell valve
must Be opened (cutting the adductor muscle.
Making an infection on the gonad) and then push
out the pearl by pressure
• Harvested pearl then washed with distilled
water. Polished with refined salt.

Composition of pearl
• Pearl consist of water, organic matter, calcium carbonate and the
residue
• Calcium carbonate 85-90%
• Organic matter (chonchiolin protein
• Water 02-04%
• Residue0.1-0.8%

Thank you