• The Korean Journal of Malacology
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• v.24 no.3
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• pp.167-173
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• 2008

The survival and growth of Glossaulax didyma didyma ($R{\ddot{o}}ding$) were measured in the laboratory under controlled conditions, such as water temperature, salinity and diet. The effect of temperature on G. didyma didyma was examined at four different levels (15, 20, 25 and $30^{\circ}C$) with 30 psu for 30 days. The results show that the growth and survival rates of G. didyma didyma were significantly higher at $15^{\circ}C$ and $20^{\circ}C$ than at other temperatures. The effect of salinity on G. didyma didyma was also examined at six different levels (10, 15, 20, 25, 30 and 35 psu) in $20^{\circ}C$ for 40 days. The results showed that the growth and survival rates of G. didyma didyma were significantly higher at 30 psu and 35 psu than at other salinities. Finally, the effect of diets on G. didyma didyma was examined with three single-component diets (prawn, shellfish and fish) at $20^{\circ}C$ and 30 psu for 60 days. The results showed that the growth and survival rates of G. didyma didyma fed on shellfish were significantly higher than those fed on prawn and fish.

• Proceedings of the Malacological Society of Korea Conference
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• 2000.11a
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• pp.26-28
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• 2000

• The Korean Journal of Malacology
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• v.27 no.2
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• pp.131-141
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• 2011

Boring caracteristics, boring rate, and predation, rates on the valves of the seed and adult clams of Meretrix petechialis by Glossaulax didyma didyma in the shellfish aquafarm and the indoor rearing aquarium were investigated by various morphometric data. The investigations were carried out from June to September, 2007. The morphology of drilled holes on the valves of M. petechialis showed the crater type as seen in the spats of Ruditapes philippinarum and M. lusoria. The sizes of the outer diameters of holes were greater than the inner diameters of the holes on the valves of M. petechialis in the shellfish aquafarm and the indoor aquarium at the laboratory. On the whole, the sizes of the holes on the valves of the seeds of M. petechialis was smaller than those bored holes on the adult valves. The location of the bored holes on the valves of the seeds varied widely with the the sizes of the individuals of M. petichialis, while most of holes on the valves of adult clams were located near the umbo position of the valves of the clams in the shellfish aquafarm and the indoor aquarium at the laboratory. On the whole, the outer and inner diameters of the bored holes increased with increase of shell lengths of the clams in the shellfish aquafarm and the indoor rearing aquarium at the laboratory. The authors could confirm experimentally the boring snail, G. didyma didyma, drilled the seeds and adult clams of M. petechialis. In the experiments for 15 days (three times repeated) in the indoor rearing aquarium at the laboratory, the mortality of dead shells to total shells of M. petechialis by boring snail Glossaulax didyma didyma was totally average 41.5%, and percent of drilled shells to total dead shells of clams by the boring snail was average 47.1%. Of total shells, percent of drilled shells to total shells of clams by the boring snail was totally average 19.3%. Predation of G. didyma didyma were greater at night than the day time. Average 0.5 seed and adult individuals of M. petewchialis were consumed per G. didyma didyma, per day. Predation varied with shell lengths of M. petechialis and shell widths of G. didyma didyma.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.520-521
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• 2000

큰구슬우렁이 (Glossaulax didyma)는 복족강 (Gastropoda), 중복족목(Gastropoda), 구슬우렁이과 (Naicidae)에 속하고 내만의 조간대에서 수심 10m 가까이의 진흙과 모래가 섞인 조하대애 묻혀 살며 일본과 우리나라 전역에 분포한다 (유, 1976). 큰구슬우렁이는 이매패나 복족류의 껍질에 구멍을 뚫어 섭식하는 육식성패류로 패류양식장 등의 해적생물로 알려져 있다 (유, 1976). 그러나 이들은 식용으로 이용되고 있어 지방에 따라 배꼽고둥, 배꼽, 우렁이, 잠빼기, 말띠, 미소라, 개소랑, 명지고둥, 가내기, 해구 등으로 폭넓게 불려진다. 이와 같이 식용으로 널리 이용되고 있는 큰구슬우렁이는 산업종으로 중요한 위치에 있어 자원관리적 측면에서 이들의 생식생물학적 조사가 조속히 이뤄져야 할 종이다. (중략)

• Proceedings of the Korean Aquaculture Society Conference
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• 2006.05a
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• pp.629-630
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• 2006

• The Korean Journal of Malacology
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• v.22 no.1 s.35
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• pp.13-22
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• 2006

Gonadosomatic index (GSI), oogenesis and reproductive cycle of Glossaulax didyma were investigated by the cytological histological obserbations and morphometric data. Samples were collected monthly from the intertidal zone of Biin Bay, Seocheon, Korea, for one year. Monthly variations in the GSI showed similar patterns with gonadal development. In the early vitellogenic oocyte, the Golgi complex and mitochondria were invovled in the formation of lipid droplet and yolk precursor. In the late vitellogenic oocytes, the rough endoplasmic reticulum and multivesicular bodies were involved in the formation of profeid yolk granules in the cytoplasm. A mature yolk granule was composed of three components: main body (central core), superficial layer, and the limiting membrane. The spawning season was from early June to late August, and the main spawning occurred between July and August when the seawater temperature was above $19^{\circ}C$. The female reproductive cycle can be classified into five successive stages: early active stage (December to February), late active stage (February to March), ripe stage (April to July), spawning stage (June to August), recovery stage (August to November). Fully mature oocytes were approximately $250-270{\mu}m$ in diameter.

• The Korean Journal of Malacology
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• v.23 no.2
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• pp.189-198
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• 2007

The reproductive cycle, egg capsules in the egg-mass, first sexual maturity, and sex ratio of the bladder moon, Glossaulax didyma ($R\ddot{o}ding$) were investigated. The gastropods collected from the intertidal zone of Biin Bay, Seocheon, Korea were studied by using histological analysis and morphometric data. The gonadosomatic index (GSI) of females and males began to increase in March and reached maximum in May. Then their values sharply decreased from late in May to August due to spawning. The condition index (CI) began to increase in February and reached maximum in May, then gradually declined in the spawning period. The CI calculated for determination of the spawning period was coincided with changes in the GSI and gonadal phases. Spawning occurred between late in May to August in females and early in May to August in males. Spawning peak was observed between July and August when the seawater temperature rose to 19 $^{\circ}C$. Reproductive cycle with the gonadal development phases of this species can be divided into five successive stages in females and four in males: in females, early active stage (December to February), late active stage (February to March), ripe stage (April recovery stage (August to November); in males, active stage (December to March), ripe stage (March to July), copulation stage (early May to August), and recovery stage (August to January). Fully matured oocytes were approximately 250-270 ${\mu}m$ in size. The egg-mass was a hat in shape, and a number of egg capsules were found in an egg-mass. An egg capsule was 0.53-0.57 mm in size. An embryo (veliger larva) hatched from an egg capsule. Percentage of first sexual maturity in females and males were over 50% for individuals that are 40.1-45.0 mm in shell radius, and 100% for those that are over 45.1 mm. The sex ratio of female to male was significantly different from 1:1 $(x^2\;=\;57.22,\;p\;<\;0.05)$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.935-944
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• 2014

To elucidate the variation of species composition, biomass and size distribution of fishery resource in the Uljin marine ranching area was investigated at the 4 stations from 2009 to 2010 based on the dredge sampling. During the survey period, a total of 41 fishery resource species were sampled with a mean density of $2,554,633\;ind./km^2$ and mean biomass was $32,946kg/km^2$. A total 36 fishery resource species were sampled with a mean density of $3,198,793\;ind./km^2$ and mean biomass $41,177kg/km^2$ in 2009 and it were sampled a total 31 species, mean $1,910,473kg/km^2$ and $24,716kg/km^2$ in 2010. The major individual-dominant species, occupying over 1% of total individuals, were Gomphina veneriformis (2,491,818 ind., 82.2%), Umbonium costatum (221,973 ind., 8.7%), Mactra chinensis (49,879 ind., 2.0%), Glossaulax didyma hayashii (49,879 ind., 1.9%), Blepharipoda liberate (37,714 ind., 1.5%) and Paguridae spp. (27,266 ind., 1.1%). The major biomass-dominant species, occupying over 1% of total biomass, were G. veneriformis (25,124 kg, 76.3%), G. didyma hayashii (2,596 kg, 7.9%), M. chinensis (2,024 kg, 6.1%), Ovalipes punctatus (921 kg, 2.8%) and Glossaulax didyma didyma (567 kg, 1.7%). From the cluster analysis based on Bray-Curtis similarity matrix of fourth root transformed data of species number and individuals was divided into 2 different groups of the fishery resource community (Group A-St.1, Group B-Sts. 2, 3, 4). The 2009 and 2010 mean Shell length (mm) of G. veneriformis was 37.73 mm, 29.76 mm and M. chinensis was 62.03 mm, 44.94 mm, respectively.