• Animal cells and systems
• /
• v.9 no.1
• /
• pp.13-18
• /
• 2005

Cannibalism plays important roles at the levels of both individual and population. To enhance overall rate of successful survival and reproduction, salamander larvae may have evolved to consume both conspecifics and heterospecifics. Consuming conspecifics could result in decreased inclusive fitness possibly by killing relatives. In several salamander species, discrimination of salamander larval siblings from non-siblings and heterospecifics to avoid such a risk has been reported. To determine whether the Korean salamander larvae consume non-siblings more often than siblings and to analyze prey preferences of the salamander larvae in several different experimental conditions, a series of foraging experiments was conducted in the laboratory. We found that 1) large cannibal larvae preyed on small sibling more often than small non-sibling in a mixed group of sibling and non-sibling, 2) cannibal larvae prefered to consume live, weak, and small larvae to dead, healthy, and large larvae, and 3) cannibal larvae consumed heterospecific tadpoles more often than conspecific nonsibling larvae in a mixed group. In addition, the larval density was positively correlated with the occurrence of spacing behavior, one of the agonistic predator behaviors among salamander larvae.

• Journal of Ecology and Environment
• /
• v.31 no.1
• /
• pp.31-36
• /
• 2008

Larvae of the long-tailed clawed salamander, Onychodactylus fischeri, have a relatively long larval period, spending a year or more within the stream where they hatch; therefore, a well-established larval population could be critical for the conservation of adult populations. To study the population dynamics of long-tailed clawed salamander larvae, we surveyed a field population once or twice a month from September, 2005 to June, 2006, and determined the age of larval clawed salamanders collected from three different populations in October, 2004 using skeletochronology. The age of long-tailed clawed salamander larvae ranged from 0 to 3 years. New recruitment of larvae in the population primarily occurred in November, 2005, and mid-March, 2006. Larvae with a snout-vent length of more than 30 mm disappeared from the streams in September, 2005, suggesting that two to three year-old clawed salamander larvae metamorphosed during this period.

• Korean Journal of Environmental Biology
• /
• v.32 no.1
• /
• pp.68-74
• /
• 2014

Scientific study has investigated the body condition differences by habitat characteristics in larvae Korea salamander (Hynobius leechii) from March to April in 2012. To examine the sensitivity of external environment (predation risk), we divided two groups according to habitat characteristic; 1) Permanent pond and 2) Temporary pond. Howere, each larva was measured by head width at the level of the eye (HWE), largest head width (LHW) and snout-vent length, and we calculated the ratio of the head size by dividing HWE/LHW. As a result, larvae were larger in permanent pond group, had a faster growth rate than in temporary pond group. When exposed to the predator, larvae in permanent pond were smaller HWE/LHW than larvae in permanent pond. Therefore, these results indicate larvae in temporary pond more sensitive to the external environment.

• Korean Journal of Environment and Ecology
• /
• v.25 no.5
• /
• pp.666-672
• /
• 2011

This study examined the different growth rate of larval salamander Hynobius leechii by the predation risk. We collected salamander's eggs from Mountain Inwang. Eggs were treated by two different conditions: (1) cue - which had a predation risk three times a day; (2) no cue - which had no predation risk. Predation risk was conducted by using chemical cue from Chinese minnows. The chemical cue treatment started from the next day after the collection and ended one week after the hatching. Between the first week and the second week after the hatching we fed salamander larvae with tubifex ad. libitium. After the treatment phase, we measured snout - vent length of the each larva on the first week and the second week after the hatching. The results showed that there was a significant difference in the growth rate by the predation risk. From these results we found that predation risk can cause the different growth rate to the larval salamander and these changes could be affect their mortality.

• Korean Journal of Environment and Ecology
• /
• v.26 no.3
• /
• pp.342-347
• /
• 2012

This study was conducted to demonstrate the relationship between experience of cannibalism and difference of phenotype in the Korean salamander Hynobius leechii from March to April 2011. We examined whether the different polyphenism of larval salamander is induced as a result of indirect cannibalism in early life cycle. We divided into two groups(one group continuously exposed to the indirect cannibalism and the other group never exposed to the cannibalism). We measured the head width at the level of eyes(HWE), the largest head width(LHW) and snout-vent length(SVL) of the each larva then calculated the ratio of the head size by dividing HWE by LHW. We found that exposure of indirect cannibalism in early life cycle cause the different polyphenism. Our result means the larval salamander responded to the chemical cue from conspecific.

• Korean Journal of Environment and Ecology
• /
• v.24 no.6
• /
• pp.744-750
• /
• 2010

This study examined the different polyphenism of larval salamander Hynobius ieechii according to two habitats, pond and stream. We collected salamander's eggs from three regions including Mountain Inwang, Surak and Gwangju. Eggs were treated by four different conditions according to predation level and habitat: high risk - which had a predation risk three times a day; low risk - which had no predation risk, pond and stream habitat. Predation risk was conducted by using chemical cue from Chinese minnows. The chemical cue treatment started from the day of collection and ended one week after the hatching. After the treatment phase, we measured the head width at the level of the eyes(HWE) and the largest head width(LHW) and snout-vent length of the each larva. We calculated the ratio of the head size by dividing HWE by LHW and made a comparison with each of the average ratio of head size according to the predation risk. The results showed that there was a significant difference in the ratio of the head size and snout-vent length according to the predation risk and habitat. From these results we found that predation risk and habitat condition can cause the different polyphenism to the larval salamander and these morphological changes could be affect their mortality.

• Journal of Korean Ophthalmic Optics Society
• /
• v.3 no.1
• /
• pp.9-13
• /
• 1998

Visual system of Korean Salamander(Hynobius leechi) was morphologically studied. Fertilized eggs in egg sacs were collected and were developed in sterile saline solution. Various sized larvae of 5-30mm in length were fixed. Specimens were paraffin sectioned and were observed under light microscope. In 5mm length larva, lens rudiment induced by optic cup was combined with sensory ectoderm. The shape of lens was changed as spherical in 12mm length larva, but the retinal layer did not differentiated into three layers. The differentiation of retinal layer was clear in 14-16mm length larva. The central region of lens fibers was degenerated. Iris and ciliary body were formed from the marginal zone of optic cup in 20mm length larva. Choroid was thicker in elder eye of 30mm length larva and cartilage developed at outer region of optic cup. The outer segment of photoreceptor cell layer grew longitudinally. Optic nerve was connected to the ventral part of brain through cartilage.

• Proceedings of the Korea Society of Environmental Biology Conference
• /
• 2005.12a
• /
• pp.38-45
• /
• 2005

The egg bags of Korean salamander(Hynobius leechii) were collected from farmlands in Gyeongsangnam-do area. The assumed breeding time, numerical variation of embryos in each egg bag, mortality and the rates of abnormalities were investigated. The toxicity of benomyl, the metabolite carbendazim and BIC which were frequently spread in agricultural area and caused spontaneous embryonic malformation was investigated. The assumed breeding time between the end of February and the end of March has the difference about a month because of a habitat and it takes about 2 or 3 weeks from laying eggs to hatching. The length of each egg bag and the number of embryos were very varied in each area. It is due to geographical variation. Among egg bags in total study area, only 406 of egg bags(17.70% of total egg bags) developed all of embryos to normal larvae, and 78.49% of total embryos were normally developed. The patterns of spontaneous embryonic malformation were 26 species from A to Z and the abnormal patterns in individual were 8 species and above. the geographical differences about the abnormal pattern were identified and 11 habitats categorized 4 groups. The most frequent abnormality in Gyeongsangnam-do area is the dysplasia of external gill. The caudal dysplasia, abdominal blister and dysplasia of fin were also frequently observed. Individuals showing severe external defect were histologically studied and they showed retinal hypo-pigmentation, thyroid carcinoma, somatic muscular dysplasia, degeneration of cephalic neuron and various organ dysplasia. Benomyl and carbendazim were treated by 10pM$^{\sim}$10uM and BIC was treated by 1$^{\sim}$40ppm to know the effect of toxicity about toxic substance of salamander. After benomyl was treated, a survival rate was sharply dropped from 2 to 8 days. $LC_{100}$ identified in $1{\mu}M$, $LC_{50}$ identified between 100nM and $1{\mu}M$. $EC_{50}$ was assumed between 10nM and 100nM. The prevalent external malformation was abdomen swelled abnormally and histo-pathological effects were abdomen, neural tube and lens hernia. This suggests that benomyl is the toxicitic substance which inhibits the development of digestive system and nervous system. The result of treated carbendazim was similar to that of the treated benomyl. The survival rate is sharply dropped between 2 and 6 days. $LC_{100}$ was identified $1{\mu}M$ and $LC_{50}$ was identified between 10nM and 100nM. This shows that cabendazim has stronger lethal toxicity than benomyl. Ventral blister, eye dysplasia and cephalic dysplasia in the individual of external malformation mean that cabendazim affected nervous system much more than benomyl. Because the toxicity of BIC affected less in the beginning but affected more in the near hatching period, the period causing toxicity is somewhat different. $LC_{100}$ identified near 40ppm and $LC_{50}$ identified near 25ppm. The external defect shows mainly ventral blister and histo-pathological results show intestinal deformities. This result suggests the BIC inhibited strongly the development of digestive system. These abnormal developments may be caused by antimitotic action, inhibition of tubulin complex, destruction of microtubule, inhibitions of neurulation and closing of neural fold, and by the inhibition of movement of neural crest cells of benomyl. These abnormal developments may be caused by the rupture of epithelium, the loss of microtubule, the reduction of spindle size, the inhibition of spindle assembly formation, the destruction of spindle poles of carbendazim. These abnormal developments may be caused cytotoxicity by inhibition of the synthesis of a number of macromolecules and similar reaction the inhibition of benomyl.