宮入貝Oncomelania nosophora(ROBSON)の日週期活動

概要

論文の詳細を見る
The environmental factors infiuencing the activities of Oncomelania nosophora (ROBSON) were analysed. The observations were made at Mamezu (Saga) in a grassy river-bed of the Chikugo River during 1956 and 1957. Under the seasons of favorable conditions this snail shows daily rhythmic activity that belongs to a type of dependent rhythmicity having two peaks in the night. During daytime it almost rests, but resumes its normal activity after sunset when light intensity reduces to about 0 lux, and after a few hours the activity reaches the maximum. Thereafter the activity declines slightly, but when light intensity increases over about 0 lux, the snails begin to resume their activity. Then after sunrise it gradually declines and scarcely moves. The first peak of activity corresponds to their feeding behavior and the second represents their returning behavior to the rest place during daytime. The principal environmental factor conditioning the daily rhythmicity is the light under the conditions of optimum temperature and wet habitat. When the temperature is lower than 10℃ and the habitat is dry, the activities of these snails are limited, while the rainfall accelerates them. In the habitat under observation their normal activities are seen in spring, autumn and rainy summer.
日本生態学会の論文
1958-10-30