Pinctada maxima
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| ( Jameson , 1901) |
Pinctada maxima (Engl. Silver- or goldlip pearl oyster, according occasionally translated in English as silver lip or silberlippige pearl oyster) is a shell - type in the family of pteriidae (Pteriidae) from the order of Pteriida . It is the largest of the six or sospecies of pearl mussels used for pearl farming.
features
The very large, slightly unevenly hinged cases of Pinctada maxima are slightly oblique-rounded to rounded-square and reach a maximum size of up to 30.5 centimeters. The left valve is moderately convex, while the right valve is flat or only slightly convex. Often the left flap is also slightly larger and the right flap sits in the left flap. The degree of bulge decreases with age. The cases are usually slightly higher than they are long. The forward curved vertebra is almost in the middle. The edge of the lock is straight and drawn out more or less long to the front and back. The back ear is small, triangular and hardly separated from the body of the case. The front, larger ear is pointed triangular. The right flap has a byssus incision under the front ear . The lock is toothless in its adult stage.
The shell is thick and heavy, so a large specimen can weigh up to 6.3 kg. The housings are light beige on the outside, with some specimens the vortex region can be green, dark brown or purple. Juvenile specimens, on the other hand, can still have a wide range of colors, from whitish, gray, cream-colored, yellowish, green, brown, purple to black, while the lighter variants often have a purple or brown zigzag pattern. From a size of about 12 cm, most specimens are then colored brown, only the vertebra still retains the color of the juvenile stage. In very old specimens, the periostracum is often already rubbed off, so that indications of the color are no longer preserved during the juvenile stage. They have no radial elements in the ornamentation.
The inside of the bowl has a clear mother-of-pearl luster. On the edge of the case there can be a slightly gold or silver-colored band of different widths, from which the shell got its English name goldlip or silverlip perl oyster .
Similar species
The main difference between Pinctada maxima and the other Pinctada species is their enormous size . The housings are light beige in color and they lack the radial component in the ornamentation. Compared to Pinctada margaritifera , they are also less bulbous and have a longer lock edge.
Geographical distribution and habitat
Pinctada maxima comes in the eastern Indian Ocean from Myanmar south to the west coast of Australia to Shark Bay , in the (sub-) tropical western Pacific from the East China Sea south of Shanghai via the Philippines, the Indonesian islands, Papua New Guinea , the Bismarck Archipelago and the Solomon Islands as far as Eastern Australia at the level of Fraser Island . It lives in shallow, warm water to a depth of around 50 meters. They need plankton-rich but clean water. In intraspecific molecular-based diversity studies, it was found that the center of the greatest diversity in Indonesia is around the Banda Sea .
Way of life
The separated-sex animals are protandric hermaphrodites , i. H. after about two to three years and a shell size of 11 cm, they first mature into males, later from a shell size of around 13 cm many specimens become females, so that the male / female ratio from a size of about 17 cm is about 1: 1. Hermaphrodites are also very rare. However, it has been observed that the larger females can also become males again.
In Northern Australia, the reproductive phase lasts from September / October to April / May, the main phase is from mid-October to December; a second smaller maximum was observed in February / March. The animals release their sexual products into the open water several times during this period, where they are fertilized. The females produce between 0.5 × 10 6 and 12 × 10 6 relatively small, yellowish eggs per season . They have a diameter of 50 to a little over 60 µm, but the average is 60 µm. About three hours after fertilization, the morula stage was reached, after five hours the gastrula stage and after about seven hours the trochophoric stage. After about 18 to 24 hours, the larvae form the D-shaped Prodissoconch I, which is initially 79 µm wide and 67 µm high. After about six to nine days, 70 to 80% of the larvae developed a rudimentary vertebra ; the length of the Prodissoconch was 110 µm and the height 100 µm. After the tenth day the vertebrae were fully developed and the Prodissoconch was 11 µm in length and 103 µm in height. The fastest developing larvae had already reached the pediveliger stage after 12 to 14 days with a fully developed foot and two dark red eye spots and went on to soil life after 15 to 17 days. At this point the Prodissoconch had reached a length to height of 270 by 220 µm to 307 by 269 µm. The majority of the larvae (70%) only reached the pediveliger stage after 22 to 24 days. The transition to soil life began on the 25th day, but on the 28th day 60% were still in the pediveliger stage. After 35 days, the great majority of Pediveligers had gone over to soil life and had settled in contact with the substrate with the right valve. The Prodissoconch had an average length of 503 µm and a height of 417 µm (range from 410 to 820 µm in length). The Prodissoconch I had a length of 90 µm (four days old Veliger larva) and a lock with five vertical teeth, three of which were in the front and two in the rear. With a length of 180 µm (about 18-day-old Veliger larvae), the Prodissoconch had six teeth, three each in the front and rear. A 24-day-old Pediveliger larva with a Prodissoconch 230 µm in length had nine teeth, four teeth in the front and five teeth in the rear. The lock teeth are completely reduced in the further course of growth. The largest specimens of Pinctada maxima found so far could be up to 30 years old.
Taxonomy
The taxon was first described in 1901 by Lyster Jameson as Pteria (Margaritifera) maxima . The World Register of Marine Species only lists the synonym Pinctada anomioides (Reeve, 1857).
use
Pinctada maxima is grown on pearls mainly in Indonesia, the Philippines, Myanmar and Western Australia. The pearls of this type can be up to 20 mm in size, they are on average the largest and most valuable pearls. The added value of pearl farms in 2004 was estimated by the FAO to be around US $ 220 million, out of a total of US $ 625 million for all pearl oyster species combined. The pearls of Pinctada maxima and Pinctada margaritifera are marketed as South Sea pearl or South Sea cultured pearl .
Trivia
The Philippine National Bank has issued a 1000 Peso note with a Pinctada maxima .
supporting documents
literature
- MH Gervis, Neil Anthony Sims: The Biology and Culture of Pearl Oysters (Bivalvia Pteriidae). 1992 full view on Google Books
Individual evidence
- ↑ a b Curtis E. Lind, Brad S. Evans, Joseph JU Taylor, Dean R. Jerry: population genetics of a marine bivalve, Pinctada maxima, Throughout The Indo-Australian Archipelago shows differentiation and Decreased diversity at range limits. Molecular Ecology, 16: 5193-5203, 2007 doi : 10.1111 / j.1365-294X.2007.03598.x
- ↑ Robert A. Rose, Shane B. Baker: Larval and spat culture of the Western Australian silver- or goldlip pearl oyster, Pinctada maxima Jameson (Mollusca: Pteriidae). Aquaculture, 126: 35-50, 1994.
- ^ H. Lyster Jameson: On the identity and distribution of the Mother of Pearl Oysters with a revision of the subgenus Margaritifera. Proceedings of the Zoological Society of London, 1901 (1): 372-394, 1901 Online at www.biodiversitylibrary.org (p. 377)
- ↑ World Register of Marine Species: Pinctada maxima (Jameson, 1901)
- ^ Paul C. Southgate: Overview of the cultured marine pearl industry. In: MG Bondad-Reantaso, SF McGladdery, FCJ Berthe: (Ed.): Pearly oyster health management: a manual. FAO Fisheries Technical Paper, 503: 7-17, Rome 2007 PDF ( page no longer available , search in web archives ) Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.
