• Animal cells and systems
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• v.11 no.1
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• pp.51-54
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• 2007

The first zoea of Pugettia gracilis is described and illustrated for the first time. Its morphological characteristics are compared with those of other known species of the genus from the northern Pacific waters. Although the Pugettia zoeas of the northwestern and the northeastern Pacifies are very similar, they can be easily distinguished by their dorsal carapace spine. In the northwestern Pacific it is spinulate with a spinous tip, while in the northeastern Pacific it is smooth with a blunt tip.

• Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.78-84
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• 1999

Ultrastructural changes in the cuticle of Paleamon serrifer associated with the intermolt cycle were examined and quantified as changes in the cuticular thickness. The cuticular thickness in each zoea stage increased with time elapsed after molting. The cuticle in the premolt stage was about 1.5 and 3 times thicker than that in the postmolt and intermolt stage, respectively. The cuticle in the premolt stage, including the molting space, was more than 5 times as thick as in the postmolt stage. In addition, newly hatched larvae were individually reared in the laboratory and body length for each specimen was measured frequently until the end of zoea VI. An average increase in body length between one zoea stage and the next is about $10\%$ of the length of the previous stage. Within individual zoea stages, the premolt stage had a body length some 0.3% longer than that of the postmolt stage, indicating a growth rate of about 0.03 mm/d.

• Animal Systematics, Evolution and Diversity
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• v.23 no.1
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• pp.69-74
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• 2007

First zoea of cyclograpsinine crab Chasmagnathus convexus (De Haan, 1835) belonging to the family Varunidae, is described and illustrated in detail based on laboratory-hatched material from an ovigerous female collected in Seumjingang river mouth, southern Korea. Morphological comparison is made with previous description of C. convexus from Japan, The first zoea of C. convexus can be readily distinguished from those of six species of Cyclograpsus intermedius Ortmann, 1894, Helicana japonica (K. Sakai and Yatsuzuka, 1980), Helicana wuana (Rathbun, 1931), Helice tientsinensis Rathbun, 1931, Helice tridens (De Man, 1835), and Pseudohelice quadrata (Dana, 1851), the other known cyclograpsinine species in Korea by having the lateral carapace spine, a pair of dorsolateral processes on the fourth abdominal somite, the exopod of antenna with three setae, and the exopod of antenna as being 24.7% length to the protopod.

• Journal of Aquaculture
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• v.14 no.1
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• pp.51-56
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• 2001

At 5$^{\circ}C$ incubation of the brooded eggs of the snow crab, Chionoecetes opilio lasted for 297 days; freshly hatched prezoea molted to become the first zoea in one hour. Length (from the tip of the rostral spines to the tip of the dorsal spines) of the first and second zoeae measured 4.8 and 6.4mm, respectively. Experimental rearing of the larvae at 5, 10, 15 and 2$0^{\circ}C$ indicated that the upper limit of thermal tolerance is 15$^{\circ}C$, as all the reared larvae succumbed at 2$0^{\circ}C$. Intermolt period from the first the first zoea to the second was 57, 32 and 23 days at 5, 10 and 15$^{\circ}C$, respectively and that of the second zoea was 52, 29 and 90 days, respectively. Largest number of larvae survived at 1$0^{\circ}C$.

• Animal cells and systems
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• v.8 no.4
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• pp.251-254
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• 2004

The first zoea of Petrolisthes trilobatus Osawa, 1996, from a female collected in Japan is described and illustrated. Its morphological characteristics are compared with those of other known species of the genus Petrolisthes. The first zoea of P. trilobatus appears very similar to those of P. lamarckii, P. asiaticus and P. hastatus. However, it could be distinguished from the others in having a spine on the lower posterior margin of the carapace, three pairs of setae on the postero-dorsal surface of the telson and minute spinules on the dorsal margins of the abdominal somites 2-5. Based on zoeal morphology, it is suggested that the zoeas of Petrolisthes could be divided into two groups: the first group (P. coccineus, P. moluccensis, P. lamarckii, P. trilobatus, P. asiaticus, P. hastatus, P. pubescens, P. tomentosus, and P. carinipes) and the second one (P. ohshimai, P. armatus, P. boscii, P. tridentatus, P. tonsorius, and P. japonicus).

• Animal Systematics, Evolution and Diversity
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• v.38 no.2
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• pp.83-90
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• 2022

Ovigerous crab of Sphaerozius nitidus of the family Menippidae was collected from Geojedo, Gyeongsangnamdo and hatched in the laboratory. Digital imaging of live zoeas of the first zoea stage of S. nitidus has been reported for the first time in the world, and its morphology has been redescribed and illustrated. This study is different from former study in that it has three unequal setae with exopod of antenna, 5+4 setae with basial endite of maxilla, and dorsomedial spine and lateral minute spine with fork of telson. The first zoea of S. nitidus has black pigments occurring behind the eyes, on the dorsal spine medially and on the basis of lateral carapace spines, on basal of basis of maxillipeds 1, 2, and posterior margins of somites 1-5, and yellowish green chromatophores on the dorsal spine.

• Journal of Aquaculture
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• v.5 no.1
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• pp.29-67
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• 1992

Life cycle and seed production of the freshwater prawn, Macrobrachium nipponense, were studied and the results are as follows : 1. Larval development : Embryos hatched out as zoea larvae of 2.06 mm in mean body length. The larvae passed through 9 zoea stages in $15{\~}20$ days and then metamorphosed into postlarvae measuring 5.68 mm in mean body length. Each zoea stage can be identified based on the shapes of the first and second antennae, exo- and endopodites of the first and second pereiopods, telson and maxillae. 2. Environmental requirements of zoea larvae : Zoea larvae grew healthy when fed with Artemia nauplii. Metamorphosing rate was $65{\~}72{\%}$ at $26{\~}28\%$ and $7.85{\~}8.28\%_{\circ}Cl.$. The relationship between the zoeal period (Y in days) and water temperature (X in $^{\circ}C$) is expressed as Y=46.0900-0.9673X. Zoeas showed best survival in a water temperature range of $26{\~}32^{\circ}C$ (optimum temperature $28^{\circ}C$), at which the metamorphosing rate into postlarvae was $54{\~}72\%$ The zoeas survived more successfully in chlorinity range of $4.12{\~}14.08{\%_{\circ}}Cl.$, (optimum chlorinity $7.6{\~}11.6\;{\%_{\circ}}Cl.$.), at which the metamorphosing rate was $42{\~}76{\%}$. The whole zoeal stages tended to be longer in proportion as the chlorinity deviated from the optimum range and particularly toward high chlorinity. Zoeas at all stages could not tolerate in the freshwater. 3. Environmental requirements of postlarvae and juveniles : Postlarvae showed normal growth at water temperatures between $24{\~}32^{\circ}C$ (optimun temperature $26{\~}28^{\circ}$. The survival rate up to the juvenile stage was $41{\~}63{\%}$. Water temperatures below $24^{\circ}C$ and above $32^{\circ}$ resulted in lower growth, and postlarvae scarcely grew at below $17^{\circ}C$. Cannibalism tended to occur more frequently under optimum range of temperatures. The range of chlorinity for normal growth of postlarvae and juveniles was from 0.00 (freshwater) to $11.24{\%_{\circ}}Cl.$, at which the survival rate was $32{\~}35\%$. The postlarvae grew more successfully in low chlorinities, and the best growth was found at $0.00\~2.21{\%_{\circ}}Cl.$. The postlarvae and juveniles showed better growth in freshwater but did not survive in normal sea water. 4. Feeding effect of diet on zoea Ilarvae : Zoea larvae were successfully survived and metamorposed into postlarvae when fed commercial artificial plankton, rotifers, and Artemia nauplii in the aquaria. However, the zoea larvae that were fed Artemia nauplii and reared in Chlorella mixed green water showed better results. The rate of metamorphosis was $68\~{\%}75$. The larvae fed cow live powder, egg powder, and Chlorella alone did not survive. 5. Diets of postlarvae, juveniles and adults : Artemia nauplii and/or copepods were good food for postlarvae. Juveniles and adults were successfully fed fish or shellfish flesh, annelids, corn grain, pelleted feed along with viscera of domestic animals or fruits. 6. Growth of postlarvae, juveniles and adults : Under favorable conditions, postlarvae molted every five or six days and attained to the juvenile stage within two months and they reached 1.78 cm in body length and 0.17 g in body weight. The juveniles grew to 3.52 cm in body length and 1.07 g in body weight in about four months. Their sexes became determinable based on the appearance of male's rudimental processes (a secondary sex character) on the endopodites of second pereiopods of males. The males commonly reached sexual maturity in seven months after attaining the postlarvae stage and they grew to 5.65 cm in body length and 3.41 g in body weight. Whereas the females attained sexual maturity within six to seven months, when they measured 4.93 cm in body length and 2.43 g in body weight. Nine or ten months after hatching, the males grew $6.62{\~}7.14$ cm in body length and $6.68{\~}8.36$ g in body weight, while females became $5.58{\~}6.08$ cm and $4.04{\~}5.54$ g. 7. Stocking density : The maximum stocking density in aquaria for successful survival and growth was $60{\~}100$ individuals/$\ell$ for zoeas in 30-days rearing (survival rate to postlarvae, $73{\~}80{\%}$) ; $100{\~}300$ individuals/$m^2$ for postlarvae of 0.57 cm in body length (survival rate for 120 days, $78{\~}85{\%}$) ; $40{\~}60$ individuals/$m^2$ for juveniles of 2.72 cm in body length (survival rate for 120 days, $63{\~}90{\%}$) : $20{\~}40$ individuals/$m^2$ for young prawns of 5.2 cm in body length (survival rate for 120 days, $62\~90{\%}$) ; and $10\~30$ individuals/$m^2$ for adults of 6.1 cm in body length (survival rate for 60 days, $73\~100{\%}$). The stocking density of juveniles, youngs and adults could be increased up to twice by providing shelters.

• Journal of Aquaculture
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• v.11 no.3
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• pp.337-344
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• 1998

This paper documented mophological changes of embryonic development and first zoea larvae of snow crab, Chinoecetes opilio. Female crabs were sampled by the Danish seine fishery at the depth about 200m in Sep. 1997 in the eastern coast of Korea. Female with newly berried eggs was reared at the water temperature of 5$^{\circ}C$ till the time of hatching. The results obtained are as follwos. Embryonic development : According to morphogenesis of fertilized eggs, the developemental process of the embryo was classified into the following seven stages : First stage (cleavage and blastula stage, 24 days) Second stage (gastrula stage, 72 days) Third stage (nauplius stage, 22 days) Fourth stage (metanauplius stage, 57days) Fifth stage (stage of a pigmentary deposit in the compound eye, 30 days) sixth stage (chromatophore appearance stage in maxillipede, 56 days) Seventh stage (hatching stage, 36 days) Larvae hatched as prezoeas and they molted to first zoea in about an hour. The first zoea is 4.6 to 5.1mm in length, 3.2~3.6mm in width. The abdomen consists of five segments and a bifurcate telson.

• Animal Systematics, Evolution and Diversity
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• v.21 no.2
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• pp.193-199
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• 2005

The first zoea of Liomera bella belonging to the subfamily Liomerinae is described and illustrated for the first time. Its morphological characteristics are compared with those of other known species of the Xanthidae The general morphology of it corresponds well with zoeas of the Xanthidae. Based on the zoeal morphology, the zoea of L. bella shows a greatest affinity with those of Xontho incisus and Pseudomedaeus agassizii by having the exopod of antenna with two setae, the terminal segment of the endopod of the second maxilliped with six setae, and the fork of telson with one stout and one smaller lateral spines.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.2
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• pp.162-166
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• 2011

The distribution and occurrence of Charybdis japonica larvae were investigated off Yeonpyong-do, Korea, in the Yellow Sea. C. japonica larvae were collected monthly at 15 stations from early June to late October in 2006 and 2007. At each station, a Bongo net with 303 and $505{\mu}m$ mesh was deployed once with a double oblique tow. No larvae were caught in June, in both years. Zoea I was predominant in late July in 2006 and early August in 2007, whereas Zoea I accounted for 84% of all larvae collected and no larval stages later than Zoea III were sampled. Megalopa were the most abundant larval stage at all stations in late August in both years. The timing of larval hatching of C. japonica may be related to that of phytoplankton blooms in the study area. The finding that Zoea I and Megalopa were predominant in the study are may indicate that C. charybdis larvae are carried by advection.