Windowpane oyster
The Capiz Shell ( Placuna placenta ) is a common from the Gulf of Aden to India and the China Sea in the Indian Ocean shell. She has economic importance mainly because of their translucent shell. It is named after the province of Capiz (Filipino: Kaposi ) on the island of Panay, which is part of the island nation of the Philippines.
Features
The strongly flattened, almost circular housing with an irregularly shaped edge and a short, straight lock edge has a diameter of 5 to max. 18 cm, commonly to 10 cm. The dorsal edge can sometimes slightly forward and backward through. The left-side flap of the Capiz Shell is flat to slightly convex, the right housing flap slightly concave. The conch shell is thick up to 1 mm; it is more or less translucent and dull white. It consists of calcium carbonate in a matrix of organic material. The calcium carbonate is present in the mineral calcite modification. The case exterior is nearly smooth, it only shows numerous, very fine, radial lirae. Most also very fine concentric growth lines can form fine to strong, like roof tiles mounted wrinkles. The external ligament is a narrow band on both sides of the vertebra. The internal ligament forms a V-shaped structure, wherein the rear limb is significantly longer than the front limb. A Palliallinie missing. It is almost purely a central, nearly round sphincter present, as well as a very small, accreting Direction between the two branches of the internal ligament front Fußretraktormuskel. The rear left Fußretraktormuskel sits within the large sphincter. Below the upper edge on the right door, the added, very small, former Byssusloch can be seen. The inside of the housing is smooth and glossy pearl- colored, with faint radial lines. Only the front and rear inner edge rückenwärtige is often roughened.
Geographical distribution and habitat
The Capiz shell is common in the Indian Ocean from the Gulf of Aden to India and the China Sea. They can also be found in the tropical and warm coastal waters of the Philippine island of the world especially in the eponymous province of Capiz. She is there usually at a depth of about 3 to 20 m, rarely to be found up to 100 m.
Way of life
The Capiz shell is dioecious. Sperm and eggs are released into the open water, then where fertilization takes place. The eggs measure 56 ± 5 microns in diameter. According to observations in the laboratory, the embryonic phase is only about 6 hours ( at 27 ° and 33 parts per thousand salinity). The first crawling Pediveliger appeared on the 9th day, the metamorphosis was complete after 14 days. A fine linen, and a Byssusloch is formed very shortly after the larval phase; the Byssusloch is growing rapidly. Most of the time of life is neither linen nor a Byssusloch present and the animal lives not grown to the sediment surface. It is not attached, flat on the slurry on the right or left valve; without preference for one or the other flap.
System
The genus Placuna, 1977 was transferred together with the genus of the family Placunanomia Anomiidae in the Placunidae family. Placunanomia but differs from Capiz Shell and the other species of the genus by the Placuna Byssalapparat, with the remains of her life connected to the substrate, while Placuna after the larval stage performs a sessile lifestyle only a short life. Therefore, according to current knowledge, the family Placunidae includes only the species of the genus Placuna with Capiz Shell as type species. It has a different of the castle Anomiidae education to which a secondary lock band counts.
Economic Importance
In the 16th century, the translucent shells of Capiz shells were used by the Spanish colonizers to the manufacture of windows, what the capiz shells called the " window panes Shells " earned. Today the Capiz flakes for decoration of room dividers, paneling, lampshades, trays, wind chimes and Christmas decorations are used. The processing of capiz shells is complicated: First, the transparent inner side is separated from the outer shell, carefully cleaned and polished. It is then soaked with a peroxide solution and made malleable, then smoothed, tailored, and cured at 200 ° C in the oven. Finally, the Capiz - disc is primed as required and colored and provided with a food-grade resin coating.
The Capiz shell can form small beads that are used in the pharmaceutical industry.
Endangering
The high demand for capiz shells has led in recent decades to a significant depletion of the mussel colonies, so that natural stocks have fallen sharply. Protection measures in the Philippines in the form of restrictions on use by the controlled allocation of state harvest licenses, creation of protection zones and the determination of minimum harvest sizes have had little success. Today, therefore, an inventory support attempts by breeding in aquaculture.