|
 The
class of mollusc,
belonging to the bivalves, with more than 10.000 kinds of mussels, is most
inportant. Only a few species can be used for the production of pearls,
and even fewer are economically significant. |
The
most important family is the Aviculides with the species Pinctada, living
in salt-water.
According to
geographical occurences, there are the breeds of Pinctada Vulgaris (Indian
and Pacific Ocean), Pictada Martensii (Japan), Pinctada Carchiarium (Australia),
Pinctada Maculata (Polynesia) und Pinctada Radiata (American pacific coast).
All species are
small with a miximum size of 7- 8 cm and can live for 7 years. The
pearls, produced by these species can´t be much larger than 9 mm
in diameter, only two other species are known to produce larger pearls:
Pinctada Maxima
(can grow up to 40 cm) and Pinctada Margaritifera (up to 20 cm). Both species
are living in the South Sea. |
|
|
Pearl-producing
freshwater pearls were
also found in the rivers of the northern latitudes (USA, England, Irland,
Scotland, Skandinavia, France, Austria, Germany...) in former times, but
due to increasing inviromental pollution, the population is falling off,
and thereforeeconomically uninpotant.
Of some economical
importance are only pearls from the specis Hyriopsis Schlegeli and Cristaria
Plikata, which are cultivated in the rivers and lakes of Japan and
China. |
| Pearl-producing
snails are the species Strombus Gigas or Giant Conch(Middle America) and
Haliotis Gigantea or Abalone (East Asia and Middle America), but pearls
are extremly seldom. |
 |
 |
A
pearl-producing species, that belongs
to the Cephalopodes, is known as Nautilus Pompilius (a cuttlefish). |
|
