Types of pearl oyster |
●Marine pearl oyster
The five main types of marine pearl oysters used in pearl farming are pearl oysters, white oysters, black oysters, mabe and abalone.
Akoya pearl oyster : Pinctada fucata martensii Dunker
It is a bivalve that produces Akoya pearls, which can be said to be the "originator of cultured pearls." The Japanese species of Pinctadafucata Gould, which is widely distributed in the Indian and Western Pacific Oceans, is Akoya. The mother oysters for pearl farming, which is carried out from the northern part of Hainan Island in China to the Leizhou Peninsula, and from around the peninsula to the border with Vietnam, also belongs to this group. ” is called.
In Japan, the northern limit of pearl oysters is said to be the Boso Peninsula on the Pacific Ocean side and the Oga Peninsula on the Sea of Japan side. It attaches to relatively shallow reefs on the bottom of the sea, up to a depth of 10m, with byssus threads. The optimum water temperature is about 15 to 25 degrees Celsius, and it is said that you need to be careful if it is below 10 degrees Celsius, and that it will die if it is below 8 degrees Celsius.
The size of the Akoya oyster is about 7-10 cm in shell height and about 40 g in weight, which is smaller than other oyster shells. The outer surface of the shell literally varies in color from dark purple to tan to greenish, but in contrast, the nacre on the inner surface of the shell has a beautiful iridescence.
Recently, as the practice of crossbreeding Japanese pearl oysters with foreign pearl oysters to create a large number of hybrids called “half-shells” and using them for farming spreads nationwide, there is even a fear of the extinction of purely domestic pearl oysters. .
White oyster (Silver/Gold-lipped pearl oyster : Pinctada maxima)
The white mussel inhabits the Indian Ocean and the Southwest Pacific around the equator, and the main sea areas are Australia, Indonesia, the Philippines, and Myanmar. In Japan, pearl farming using white clams is also carried out in Kagoshima and Okinawa.
They live in a wide range of habitats, ranging from shallow seabeds exposed at low tide to deep waters as deep as 70m. The water temperature suitable for inhabitation is 25 to 29 degrees Celsius, and mussels become active at 28 to 29 degrees Celsius. Conversely, if the water temperature drops below 25°C, the movement of shellfish will be inactive. There is a close relationship between the water temperature and the thickness of the nacre layer, that is, the "rolling" of the pearls, and the difference in water temperature in the cultivation area also affects the cultivation period.
White mussels are the largest pearl oysters used in pearl farming. In Australia, shell heights of 25 cm and weights of 2 kg are common, but larger ones can reach 30 cm or more in height and weigh as much as 5 kg. On the other hand, unlike Australia, most of Indonesian white mussels are artificially collected seedlings, and they are generally small. The difference in the size of this shellfish is related to the size of the cultured pearls. Australian pearls are 10-20mm, while Indonesian pearls are small at 8-13mm.
There are two types of white lip, one with a silvery-white nacre rim and the other with a yellow nacreous rim. The former is called "Silver lip" and the latter is called "Gold lip". Silver-lipped pearls are common in Australia, while gold-lipped pearls are common in the Philippines and Indonesia. There are many yellow ones such as yellow and golden.
Black-lipped pearl oyster Pinctada margaritifera
The black-necked mussel has a wide range of habitats, extending from the Kii Peninsula and southwards to Amami and Okinawa in Japan. Its distribution extends from Taiwan to the West Indian Ocean, the Persian Gulf and the Red Sea, or from the South Pacific such as Micronesia and Polynesia to the Gulf of California and the Gulf of Panama. Due to its wide distribution, it is classified into several subspecies, such as Pinctada margaritifera cumingi from Polynesia, Pinctada margaritifera mazatlanica from California and Panama, and Pinctada margaritifera eryth-rensis from the Red Sea. increase.
The black clam is a bivalve that inhabits well-drained coral reef waters at depths of more than 10 meters and adheres firmly to rocky areas with byssus threads. The optimum water temperature is 24 to 29 degrees Celsius, and it is said that growth stops below 18 degrees Celsius, becomes dangerous below 15 degrees Celsius, and dies at 11 to 12 degrees Celsius. Black lipped mussels are generally smaller than white lipped mussels, and are 4-5 year old with a shell height of about 15 cm. The inner nacreous layer of the shell is silvery white, and the peripheral part contains a lot of unique black pigment, and the color is blackish, ranging from silvery gray to black purple. Polynesian black-lipped oysters in particular have a very beautiful reddish dark green color, and these mother oysters produce wonderful pearls with a similar color called "peacock color".
Mabe (Black-winged pearl oyster : Pteria penguin)
It is a bivalve with a wing-like rear ear that is more than 20 cm in size. In Japan, they inhabit the waters south of Shikoku, and semi-shaped pearls are cultivated using this shellfish in the Amami region. The range further extends from Hong Kong, Malaysia, Indonesia, Thailand, Cambodia and the Western Pacific to the Indian Ocean. It inhabits deep waters at a depth of about 20m, and firmly adheres to reefs, sea pine, and coral trunks with strong byssus threads. Mabe do not live in groups. The outer surface of the shell is black, but the inner
The mother-of-pearl has a very beautiful iridescence and exhibits a wonderful pearl luster.
A subspecies of mabe is the rainbow mabe (Western Winged pearl oyster:Pteria sterna). This shellfish is rather small, about 6 to 14 cm in size, and inhabits the waters of the Gulf of California from Baja California to Peru. Purple to black pearls are produced from this pearl oyster, and recently Mexican pearl traders have started culturing black pearls using this mother oyster.