Status of Windowpane oyster Placuna placenta placenta (Linne

Status of Windowpane
oyster Placuna placenta
(Linne)
Linne) population in Goa
Baban Ingole & Sandhya Clemente
NIO, Goa
•Human interest in molluscs as food
& objects incorporated or depicted
in art and religion far predates any
scientific study
•Shells – as ornaments, money
among primitive people over
4,000yrs
•Among the bivalves, ‘OYSTER’
ranks highest in dollar value
•The cowries and tusk shell
were used as money
Botticelli's Birth of Venus has
Venus rising from the foam in
a Scallop shell.
PLACUNA PLACENTA -THE
WINDOWPANE OYSTER
•Commonly known as “kapiz” “Methy” in Goa
•Shell – flat thin rounded and translucent
•Muddy or sandy substrata – from shallow
water to 100m depth.
•Filter feeders
After two years, when it reaches maturity, the
shell becomes white and shiny
DISTRIBUTION
Gulf of Aden around
India, the Malay Peninsula,
southern coasts of China
and northern coasts of
Borneo to the Philippines.
Major Fishery:
East coast :Kakinada bay, where
10% population produce pearl
West coast: Gulf of Kuchchh-26%
population used to produce pearl.
ECONOMIC IMPORTANCE
• Meat – food value
• Shell
–
curios,
shellac,
soldering lead and paints
• Lampshades and wind-bells.
• Pearls
–
used
in
pharmaceutical preparation
of
medicines
and
in
ornaments
• Kakinada Bay – revenue
obtained
from
pearl
is
90,000/kg.
ARCHEOLOGICAL SIGNIFICANCE
• During the Filipino Spanish period (15thcentury) shells were used for
windowpanes in houses
• Most of the traditional Goan houses (14thcentury)–window pane oyster.
• The windows are made from the flat valve of the shells.
• Mombassa (16th century) - Among the most numerous items on the
wreck of Santo Antonio ship were finish items from window pane shell“TRADING”
13--14
11--12
9--10
7--8
5--6
3--4
Size Frequency of Placuna placenta from Goa
1--2
% Frequency
35
30
25
20
15
10
5
0
Size class (cm)
• Shell size (dia) varied from 1.8-13.1 cm
•Size range of 3-8cm form major population.
•Highest abundance ≈ 350 ind.m-2
•Smallest & largest size showed low density.
• Total weight of oyster– 116.3 gm (12 cm dia.)
79.99 gm (11 cm dia.)
• Single oyster yielded 14 pearls
• Pearls – spherical, ivory white in color
Pearls from Placuna placenta
PEARL FORMATION
Principal causative factorfactor- (organic or inorganic
origin)
Parasites (adults or larvae), molluscan eggs,
sand grains, part of shell of same animal.
•Enter the oyster when the shell valves are
open for feeding and respiration.
•The mollusc protects itself by depositing
nacreous matter at the point of invasion.
•Thus a most coveted
•treasures of the ocean
•the “PEARL” is formed.
“BUT” Windopane
Oyster population is
dwindling
Coastal pollution is a
major cause
Presently, major fishery
at Kakinada bay
In Goa, although
available at few places,
ecology is not known
Hence, immediate
attention is needed