• The Korean Journal of Malacology
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• v.26 no.1
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• pp.45-49
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• 2010

Up until now, we have identified 17 exotic species of Mollusca in Korea. These include Achatina (Lissachatina) fulica, Limax flavus, Limax marginatus, Deroceras reticulatum, Hawaiia minuscula, Zonitoides yessoensis, Zonitoides arboreus, Physa acuta, Pomacea canaliculata, Pomacea insularus, Crepidula (Crepidula) onyx, Mytilus galloprovincialis, Xenotrobus securis, Perna viridis, Argopecten irradians irradians, Pinctada fucata, and Pinctada margaritifera. Among them Achatina (Lissachatina) fulica, Pomacea canaliculata, Pomacea insularus, Argopecten irradians irradians, Pinctada fucata, and Pinctada margaritifera were intentionally introduced, whereas remainings were unintentionally introduced into Korean fauna. These foreign species can be divided into three groups on the basis of their habitats: A. fulica, L. flavus, L. marginatus, D. reticulatum, H. minuscula, Z. yessoensis, and Z. arboreus in terrestrial habitat; P. acuta, P. canaliculata, and P. insularus in fresh water; and C. onyx, M. galloprovincialis, L. fortuneikikuchii, P. viridis, A. irradiansirradians, P. fucata, and P. margaritifera in sea water. Taxanomically, 11 species belong to Gastropoda, whereas 6 species are classified to Bivalvia.

• Ocean and Polar Research
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• v.27 no.3
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• pp.351-358
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• 2005

Reproductive condition of the tropical blacklip pearl oyster, Pinctada margaritifera collected during the period July through September 2003 from Chuuk Lagoon, Federated State of Micronesia was investigated using histology. The level of gonad development for each pearl oyster was determined with an average score of five microscopic fields, and the average score was used as the maturity index (ML). All wild pearl oysters collected in July did exhibit fully ripe eggs in their ovaries ($45{\sim}50{\mu}M$ in diameter), indicating that they were ready for spawning. In mid August most wild pearl oysters were in spawning and M1 dropped dramatically from mid- to late September, suggesting that the wild pearl oyster completed spawning during this period. In contrast, the cultivated pearl oysters collected in mid-September held ripe eggs in the ovaries and only a few of them spawned, indicating that gonad maturation of the cultivated pearl oyster was somewhat slower than that of the wild pearl oyster in Chuuk Lagoon during the summer period. Histological analysis also indicated that spawning of the pearl oyster is rather incomplete and they may spawn continuously during summer.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.5
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• pp.205-210
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• 2008

Pearl is the organic gemstone which does not come from mines but from the biomineralization inside mollusc. Mollusc with nacre on inner surface of the shell is inevitable to make pearl. In this paper we researched and analyzed the pearls cultured using Pen shell (Atrina pectinata) which is not used in pearl farming industry but has potential to make pearls because it has thick and beautiful nacre inside the shell. SEM analysis was conducted to reveal the pattern of nacre on the Atrina pectinata pearl. Specific characteristics as sea-water pearl are detected by further analysis with ED-XRF. Aragonite specific peaks such as $1083cm^{-1}$ and $705cm^{-1}$ were shown by Raman analysis. UV-Vis analysis of Atrina pectinata pearl showed different pattern of spectrum compared with Pinctada margaritifera pearl. The reason for this discrepancy is assumed by the metabolic difference of each species.