• Applied Microscopy
• /
• v.44 no.2
• /
• pp.47-52
• /
• 2014

Fine structural characteristics of eggs (nits) found on the scalp hairs of Korean children were observed with scanning electron microscopy. An egg is structurally composed of four parts: the cementum, nit body, operculum, and aerophyle. The total length of an egg is about 1.5 mm. The glue secreted from the female louse completely surrounds the 1 mm hair shaft and forms the cementum. The thickness of the cementum at the end of the nit body was found to be more than 5 times the thickness at the end toward the scalp. The nit body is shaped like a goblet with a very smooth surface. The operculum and aerophyles are located at the apiculus area. In the circular operculum, there are 10 aerophyles concentrated on the side of the hair shaft surface that are shaped like a dome. Three aerophyles in the center are surrounded by 7 aerophyles. Each aerophyle is dome shaped with a diameter of $65{\mu}m$ and a respiratory pathway with a $15{\sim}25{\mu}m$ opening at the center. On the cut surface where the operculum is separated as the egg hatches, long grooves about $1{\mu}m$ thick are uniformly formed transversely. These long grooves facilitate the separation of the operculum through body expansion at the time of hatching.

• Development and Reproduction
• /
• v.22 no.3
• /
• pp.275-281
• /
• 2018

The purpose of this study is to examine fluctuating asymmetry of eye diameter, maxilla length, operculum length, and the number of pectoral fin ray and pelvic fin ray between ploidy and sex in diploid and triploid marine medaka, Oryzias dancena. In all experimental groups, eye diameter and maxilla length showed no significant difference between left side and right side (p>0.05). Results of operculum length in triploid male group and pectoral fin ray's number in diploid male group showed similarity ones with results of operculum length in triploid female group and pectoral fin ray's number in diploid female group (p<0.05). However, the operculum length in diploid male group and pectoral fin ray's number in triploid male group showed consinderable difference with those of operculum length in diploid female group and pectoral fin in triploid female group. Findings of pelvic fin ray's number in all groups were similar to those of pectoral fin ray's number in all groups (p<0.01).

• The Korean Journal of Malacology
• /
• v.30 no.1
• /
• pp.25-32
• /
• 2014

The age and growth of Neptunea (Barbitonia) arthritica cumingii sampled from the West Sea of Korea were determined from 1,062 operculums from October 2007 to September 2008. Age of Neptunea (Barbitonia) arthritica cumingii was determined from the rings on the operculum. The relationship between shell height (SH; mm) and shell width (SW; mm) was expressed by the following equation : SW = 0.5757 SH + 0.222 ($R^2$ = 0.8723), and shell height (SH; mm) and total weight (TW; g) was highly correlated by the equation : TW = 0.0002 $SH^{2.8162}$ ($R^2$ = 0.9121). The main spawning periods was estimated June to July through fatness index analysis. The relationship between shell height and ring radius of operculum in each ring group was expressed as a regression line. Therefore, there is a correspondence in each ring formation. Based on the monthly variations in the marginal index (MI) of the operculum, it is assumed that the ring of this species was formed once a year during the period of July to August. Growth curves for shell height (SH) and total weight (TW) fitted to the von Bertalanffy's equation were expressed as follows : $$SH_t=173.964(1-e^{-0.164(t+1.173)})$$ $$TW_t=407.952(1-e^{-0.164(t+1.173)})^{2.8162}$$

• Korean Journal of Environmental Biology
• /
• v.26 no.3
• /
• pp.138-144
• /
• 2008

The effects of salinity on oxygen consumption, operculum movement number and ammonia nitrogen excretion were examined in cultured tilapia, Oreochromis mossambicus (total length 10$\pm$1.0 cm, total weight 17.3$\pm$4.2 g). The fish were exposured to certain salinities (0, 3, 9, 15, 21, 27 and 32 psu) step by step with 3 psu$\cdot$d$^{-1}$ and changed rapidly from certain salinity to another salinity. The oxygen consumption of the fish which was transferred step by step showed increasing tendency in the range of 3 $\sim$ 27 psu, but markedly appeared very low value at 32 psu. The tolerance limit in tilapia by salinity change without acclimation was shown 23.3 psu from 96-h TL$_{50}$. The oxygen consumption, operculum movement and ammonia nitrogen excretion of fish which was transferred rapidly from certain salinity to each salinity (0, 9, 15, 21 and 32 psu) showed a changing point at 15 psu; they showed increasing and/or decreasing pattern before 15 psu, and showed decreasing pattern after 15 psu. From these results, it was concluded that the appropriate salinity without physiological change for Java tilapia was below 15 psu.

• The Korean Journal of Malacology
• /
• v.25 no.3
• /
• pp.189-196
• /
• 2009

Based on 1,260 samples, the age and growth of purple whelk, Rapana venosa (Valenciennes) (Gastropoda:Muricidae) have been investigated. The samples were collected monthly during one year time (from February, 2004 to January, 2005) from the West Sea of Korea. The age of R. venosa was determined by the ring of the operculum analysis. The relationship between whelk's shell height and ring radius in each ring group was expressed as an equation of linear regression and later a correspondence in each ring formation was determined. Based on the monthly variations in the marginal index (MI) of the operculum, it was assumed that the ring of this species has been formed once a year during the period from July to August. The relationship between shell height and shell width was expressed by the equation SW = 0.7867 SH - 6.3988 ($R^2$=0.8604); and between shell height and total weight by the equation $TW=0.0000626{\times}SH^{3.206}$ ($R^2$=0.8324). The purple whelk's spawning period was estimated through the fatness analysis and has occurred during the period from May to July. Obtained results suggests that the ring formation occurs once a year (in July) and the length of time period since the first ring has been formed on the operculum is approximately 13 months (1.08 year). The purple whelk's growth curves for shell height and total weight fitted to the von Bertalanffy's equation and were expressed as follows: $SH_t=199.653(1-e^{-0.104(t+2.478)}$ $TW_t=1484.105(1-e^{0.104(t+2.478)})^{3.206}$.

• Korean Journal of Environmental Biology
• /
• v.38 no.4
• /
• pp.507-517
• /
• 2020

Several methods including morphometric analysis were used to distinguish small yellow croaker (Larimichthys polyactis) from yellow croaker (Larimichthys crocea), which have very similar external shapes. Morphometric analysis showed four considerable differences (p<0.05) among the total 48 morphometric dimensions, but no differences were seen in the classical dimensions (p>0.05). Rather, significant differences were seen in two truss dimensions: Insertion of dorsal fin base - origin of pectoral fin base and origin of anal fin base - origin of pectoral fin base, and two head part dimension: most anterior extension of the head - above of eye and above of eye - posterior aspect of operculum(p<0.05). However, the yellow croaker had higher values than the small yellow croaker in the other three morphometric dimensions except for the head part dimension of above of eye - posterior aspect of operculum of the four morphometric dimensions (p<0.05). The X-ray photographs indicated that the small yellow croaker (45.1±2.34°) had 8.4% more curved vertebral column than the yellow croaker(38.4±1.82°). A diamond-shaped cranium was found when the skin was peeled off from both fish but the commonly held fact that only the small yellow croaker has a diamond-shaped cranium is not accurate. Our results confirmed that the two fish could be definitely distinguished by their external body shape.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.54 no.4
• /
• pp.568-573
• /
• 2021

A single leptocephalus specimen of Albula glossodonta belonging to the family Albulidae under the order Albuliformes, was collected from the southern sea of Korea in May 21, 2019. This species is distinguished from A. vulpes in the number of melanophores at the base of the caudal fin. In addition, our specimen was readily distinguished from A. argentea in having no melanophores on the operculum, at the base of the dorsal fin and in front of the pectoral fin. Also it was well distinguished from A. gilberti in having no melanophores on the operculum, in front of the pectoral fin and on the lateral body. A molecular analysis based on 467 bp sequences of the mitochondrial DNA 16S rRNA shows that the leptocephalus is well matched to A. glossodonta adult (K2P distance=0.002). We report the first occurrence of A. glossodonta leptocephalus in the Korean waters, and propose it's new Korean name, "Nam-bang-yeoeul-myeol".

• Parasites, Hosts and Diseases
• /
• v.21 no.2
• /
• pp.150-156
• /
• 1983

Five cases of Diphyllobothrium latum infection were proved by collection of worms after treatment with bithionol, niclosamide or praziquantel, during 1975~1983. The patients were 4 males and one female aged 10~64 years residing in Seoul or Wando-gun, Chollanam-do, Korea. All of them remembered the history of eating several kinds of raw marine fish and 2 persons said they ate the raw mesh of perch, Lateolabrax japcnicus. Three amcnE them experienced abdominal pain, 2 natural discharge of a chain of segments, but none revealed any sign of anemia. The average egg size in stool varied $59~67{\times}41~48{\mu\textrm{m}}$ according to cases. The eggs were characterised by ovoid to elliptical shape, terminal operculum, and distinct abopercular protuberance. One naturally discharged segment (30cm) and 4 complete strobilae (320~680cm) with scolices obtained after treatments were examined. The morphological characters of proglottids such as rosette-form uterus with 3~6 loops, vaginal pore included in the cirrus sac, separated seminal vesicle from cirrus sac, etc. were all compatible with D. latum. These are the 7th~11th cases of D. latum infection proved by worms in Korea.

• Fisheries and Aquatic Sciences
• /
• v.14 no.2
• /
• pp.148-160
• /
• 2011

Thirty-one gross abnormalities that have been observed in tilapia are described: 10 fin, five eye, five jaw, four body shape, three head, two yolk sac, one operculum, and conjoined twins. Twenty-one have been described in published papers; the others were obtained from a survey. Breeding experiments revealed that three were heritable, while six were not heritable. Five could be caused by a bacterial infection, and one could be produced by a fungus. Four deformities were in offspring of males that had been injected with methyl methane sulphonate. Three were produced when sperm was treated with methyl methane sulphonate. Six were observed during sex reversal studies, and one was found following heat shock of fertilized eggs. Three were observed in polluted river water. The cause of other deformities is not known.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.49 no.5
• /
• pp.675-677
• /
• 2016

We report the first occurrence of a tailless Girella leonina, collected from Jeju Island, Korea, in July 2016. This specimen has 10 scales below the median spinous portion of the dorsal fin, a black posterior margin of the operculum, and no pale vertical band on the body, and is therefore similar to the normal species, except that it has no caudal peduncle or caudal fin. The posterior parts of the dorsal and anal fins are gathered vertically at the posterior end of the body. A radiograph indicates that this abnormal specimen is lacking the vertebrae after vertebra 20.