is a shell-less pulmonate and lives in the middle and high intertidal zone. It is considered as a commercially important species owing to its high nutritive value and beneficial effects in Chinese medicine. is also regarded as an important representative species for a better understanding of the evolution from aquatic to terrestrial life since this species has two methods of respiration-epidermal respiration and pulmonary respiration. Epidermal respiration plays an important role in the underwater life stageor stationary stage of , while pulmonary respiration contributes to its creeping or terrestrial life stage. In the present study, the effect of body size, water temperature (15℃, 20℃, 25℃, and 30℃), salinity (5, 15, 25, 35, and 45) and pH (7.5, 7.8, 8.1, and 8.4) on underwater oxygen consumption rate (OCR) and epidermal histology was determined to provide valuable information for understanding the respiratory mechanism of and its evolutionary characteristics. These results demonstrated that smaller had higher underwater OCR than larger individuals. Epidermal respiration differed significantly at various temperatures, salinities, and pH values (<0.05). The OCR and the inner and outer diameter of the mucus gland increased as water temperature increased below 25℃. The highest values were observed at 25℃ and then began to decrease gradually at temperature above 25℃. The thickness of the dermis decreased with increasing temperature. The number and the inner and outer diameter of the granular gland did not differ considerably between temperature groups. The differences with respect to salinity in dermis thickness and inner and outer diameter of the mucus gland/granular gland were the same as those with respect to temperature. The highest values were observed at salinity 25. The pH also had a significant effect on respiration. The OCR and inner and outer diameter of the mucus gland increased with pH, while dermis thickness and inner and outer diameter of the granular gland decreased. The number of granular glands first increased and then decreased; peak values were observed at a pH of 8.1. However, respiration levels decreased with time in all groups. In conclusion, environmental factors such as temperature, salinity, and pH had significant effects on underwater epidermal respiration. Items such as dermis thickness and the inner and outer diameter of the granular gland play more important roles in epidermal respiration in than the granular gland, which may be key to keeping the body wet and protecting it from invasion or damage from its habitats. showed optimum respiration metabolism in water at a temperature of 25℃, salinity 25, and pH 8.1. At lower temperature (15℃), higher salinity (45 psu), and lower pH (pH 7.5), this organism will be under considerable stress. This might be related with to the factors associated with its optimal living conditions. The results of this study will provide basic information for the protection and aquaculture of this species and will also be helpful to understand the evolution from aquatic to terrestrial life.