• Development and Reproduction
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• v.17 no.1
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• pp.25-35
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• 2013

We investigated the effects of shell height on reproductive potential of the female Rapana venosa in three regions of different salinities (the coastal zone of the Gwangyang Bay (S-1); the upper reaches (S-3); lower reaches (S-2) of the Seomjin River). The number of egg capsules, egg capsule height, and fecundity associated with reproductive potential of larger female rapa whelks were higher than those of smaller individuals in all three regions. Correlation analyses showed that there is a significant positive correlation between egg capsule and female shell height. Mean of shell heights, egg capsule heights, the number of egg capsules in an egg mass, and fecundity in an egg capsule produced from female individuals inhabiting S-1 region were markedly higher than those inhabiting S-2 and S-3 regions. In particular, the fecundity of the rapa whelk increased with the salinity and shell height. Although large rapa whelks produced a large number of egg capsules at S-1 region, those at S-3 habitat laid less egg capsules with smaller size. If these rapa whelks were put into S-2 region, the number of egg capsules produced by a female at S-2 region was slightly larger than those produced by a female at S-3 region. This provides a clear evidence that the number of the egg capsules can be controlled by the salinity. In the coastal zone of the Gwangyang Bay and the upper reaches of Seomjin River, the fecundity of this species was estimated to be approximately 182,000-1,302,000 eggs/ind./yr.

• The Korean Journal of Malacology
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• v.19 no.2
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• pp.111-115
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• 2003

Morphological aspects of the eggs and egg capsules of the neptune whelk, Neptunea constricta (Dall, 1907) (Mollusca: Gastropoda: Buccinidae) are described and illustrated with capsular dimension and enumerations of eggs and egg capsules based on the specimens collected from continental shelf of East Sea, Korea.

• Korean Journal of Ichthyology
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• v.22 no.4
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• pp.217-224
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• 2010

An investigation was carried out to obtain basic information needed to develop methods for artificial propagation and conservation of the mottled skate Raja pulchra, an important food resource in western Korea that has declined from overfishing. In this paper we provide evidence of multiple spawning and describe properties of the ovary, and morphology of the egg capsule and the fully-formed offspring. The vitellogenic follicles in the ovary was $179.8{\pm}57.1$ (54~247) and can be classified into five size groups, which the last group of ova are considered as the moving to the capsule gland where fertilization and encapsulation of ova take place. The morphology of the egg capsule of R. pulchra is unique among the species of the family Rajidae and showed multi-embryo characteristics, having two to six yolks in each capsule. The adaptive morphological changes of larvae developing inside the egg capsule are described based on specimens extracted from the capsule.

• Development and Reproduction
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• v.18 no.1
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• pp.25-31
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• 2014

This study was investigated spawning behavior, structure of egg masses and egg development in Aplysia kurodai inhabiting the coastal waters of Jeju Island, Korea. The mating and courtship behavior of A. kurodai occurred in the form of unilateral copulating with chain formation. In chain copulation, only the first animal acted as a female; the second and succeeding animals acted as males (sperm donors) to the animals in front and as females to the animals behind. The fertilized eggs were packaged in capsules that are embedded in jelly to form a cylindrical string called an egg masses. The number of capsule per cm of the egg masses was 55 to 60 capsules and each capsule within the egg masses held 15 to 25 eggs. After spawning, the egg masses were bright yellow or orange in color. This egg masses color not changed until embryos developed into trochophore stage. Thereafter, as embryo developed from trochophore stage to veliger stage the egg masses color became brownish. The fertilized eggs were spherical, with a diameter of approximately $80{\pm}1{\mu}m$ at spawning. At 5 to 6 days after spawning, the embryo developed into trochophore stage and began to rotate within the egg capsule. In the trochophore stage, the precursor of the velum, called the prototroch or prevelum, developed. At 10 days after spawning, the prevelum is transformed into the velum, and the trochophore developed into veliger stage. Between 10 to 15 days after spawning, the veligers broke out of the egg capsule, and hatched as free-swimming larvae.

• Korean Journal of Ichthyology
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• v.21 no.4
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• pp.283-286
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• 2009

The egg capsule of Hongeo koreana is newly described based on two egg capsules extracted from the uterus of a female collected near the type locality, the southwestern coast of the Korean Peninsula. The egg capsule of H. koreana has the following characters: medium sized, measuring 124.5~133.7 mm in total length including horns, 102.8~109.4 mm in length excluding horns, and 41.0~42.2 mm in maximum width; asymmetrical, with the egg capsule more convex ventrally in lateral view; the surface relatively smooth, with longitudinal striations distinct, and covered with masses of sticky silky fibers; anterior and posterior aprons distinct; all four horns short, tube-like in shape, elliptical in cross section, anterior horns recurved inwardly; respiratory fissure present at tip of each of the four horns. The color of the fresh capsule is bright brown.

• The Korean Journal of Malacology
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• v.2 no.1
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• pp.10-12
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• 1986

Pettancylus nipponicus (freshwater limpet) collected from the Lake Choon Cheon were cultrued in aquarium and studied in the respects of an egg deposition and the developmental characters of cleavage. The species were collected only in the Lake Uiam and Choon Cheon and easily sampled on the debris like vinyls and cans. Those smooth surfaces were suitalble substrata for attaching. P. nipponicus, about 4 mm in adult, deposited an egg in one calcareous egg-capsule on the aquarium walls, while many eggs are surrounded in a jelly-like egg-envelope in the most gastropods. And another special features was that an egg-capsule was consisted of two valves and the suture was opended as hatching. A diameter of its egg was $55{{\mu}m}$ and the length of an egg capsule was $620{{\mu}m}$ and $510{{\mu}m}$ in long and short diameter, respectively. It took about 8 hours from beginning cleavage to 16-cell stage and about one year to become an adult.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.531-532
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• 2000

The morphology of molluscan egg capsule is generally regarded as being species specific (Turner, 1992), and form and structure of the egg capsule reflect the degree of anatomical complexity of the reproductive organs (Fretter ＆ Hian, 1984). Ceratostoma rorifluum and Ocinebrellus inornatum are common and widespread muricid species found throughout the Korean rocky and boulder shores, and Neptunnea constricta is found frequently from continental shelf of the eastern sea of Korea. In spite of their predominance along the Korean coasts, morphology of their eggs and egg capsules is unknown so far. The purpose of the present study, therefore, is to provide descriptions and illustrations for identifying egg capsules of the foregoing 3 stenoglossan gastropod species. (omitted)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.625-631
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• 2003

The aim of the present study was to investigate the ecological relationship between female body size (=shell length) and fecundity in a Korean population of protandric hermaphrodite, Crepidula onyx Sowerby, using 6 reproductive variables (the number of capsules per brood, capsule size, the number of embryos per capsule, total number of embryos per brood, egg size, and larval size). The investigation was based on 32 females, 107 egg capsules, 263 eggs, and 250 veliger larvae sampled in January 2000, from Yangpo, the southeastern coast of Korea. All foregoing reproductive variables, except larval size, were significantly correlated with the female body size (p<0.001$\~0.01$). There was a significant increase both in the number of capsules per brood and the number of embryos per capsule with female body size (p<0.001). Consequently, the fecundity of the female C. onyx increased with female body size to over 14.65 mm (the minimum size of egg brooding in the present study). This investigation, therefore, provides additional evidence that female fecundity of protandric hermaphrodites is positively correlated with female body size.

• The Korean Journal of Malacology
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• v.9 no.2
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• pp.1-15
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• 1993

The reproductive ecology of the purple shell, Rapana venosa was investigated by the histological observations on depositions of the egg capsules, and hatching of larvae in the laboratory and the subtidal zone of the vicinity of piung-do, Chollabud-do, west coast of korea, for one year from June 1992 to May 1993. The results are summarized as follows:1. Rapana venosa is dioecious in sex. The ovary is composed of a number of ovarian lobules, and the testis comprises a number of ovarian lobules, and the testis comprises of gonads could be classified into 4 stages in males and 5 stages in females: 1) growing stage(in female subdivided into 2 stages of early and late growing stage). 2)mature stage. 3)spent stage or copulationstage. 4)rdcovering stage. The early growing stage in females of the purple shell was in September through February, late gorwing stage was in October to March, mature stage was in September to January, mature stage was in September to July, copulation stage was in Februaty to June and recovering stage in April to October.3. Spawning occurred 3-4 times at intervals of 1-3 days, and completed within 10 days from the beginning of spawning during the spawning season of the year.4. From the results of laboratory and field observations, egg masses are composed of a number of egg capsules, egg masses are occurred from May to late August, and in mid August depositions of egg mass in composed of 90-113 egg capsules, fecundity in an egg capsule was ranged 984 to 1,241 eggs(average 1,096 egg). Therefore, fecundity in total egg capsules spawned per individual during the spawning season is estimated as approximately 320,000 to 450,000 egges.5. The incubation period during deposition of an egg capsule to hatching larvad tood 17 days at 18.3-20.4%C(water temperature)and 1.021 (specific gravity fo sea water).

• Animal cells and systems
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• v.3 no.4
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• pp.375-383
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• 1999

Gonadal development, gametogenesis, reproductive cycle, and first sexual maturity of Reishia clavigera were investigated monthly from July 1998 to June 1999 through cytological and histological observations. R. clavigera had separate sexes, and was an internal fertilizer. The ma1e penis was located near the two tentacles. The ovary and testis were composed of a great number of oogenic lobules and spermatogenic tubules, respectively. The size of ripe oocyte ranged from 130 to 140 ${\mu}$m in diameter. The peripheral cytoplasm of the germinal vesicle of the ripe oocyte in many cases were surrounded by smaller yolk granules, while the eccentric cytoplasm was occupied with larger ones. The reproductive cycle of R. clavigera could be classified into five successive stages: early active, late active, ripe, spawning, and recovery. Spawning of females occurred from early July to August when the seawater reached above 24.8$^{\circ}C$. Spawning of males occurred from early June to August in the water above 22.8$^{\circ}C$. Minimum size for sexual maturity of both sexes was above 10.0 mm in shell height. Each egg capsule was a cylinder or spindle in shape, 4-6 mm in length and 1-2 mm in width. Colors of newly spawned egg capsules showed yellowish white or pale yellow, while those with veliger larvae showed pale black, and released larvae or dead egg capsules showed black violet. The fecundity in an egg capsule ranged from 70 to 91 eggs (mean＝80.28 eggs).