ハマダンゴムシの日週期活動 : IV.波の週期的な運動に伴なう週期活動(ヒゲナガハマトビムシとの比較)
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概要
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Characteristic activities of animals, which are concerned with ebb and flow, have been studied by many authors.(WELSH'38,CALHOUN'44,MORI'45,'50,BROWN et al. '48,'49,'51,'53,'54,'55,'56). Generally, it can be said that both internal and external factors have some relations to the rhythmic movements of animals. From this point of view, observations and experimental analyses of the locomotor activity with the periodic movement of waves were carried out on the sand hopper, Talorchestia brito and the shore sowbug, Tylos granulatus, under natural and laboratory conditions. 1) Sand hopper and shore sowbug are very common along the drift line on the coast of Tottori. They exhibit locomotor activity in the night, but not in the daytime. Their usual positions in sand in the daytime are indicated in Fig. 1. 2) These animals exhibit the following characteristic movement in the night. When the wave advances to the beach line, the shore sowbugs turn to the right or left just in front of the surf and move towards the higher parts of the shore so as to not to be carried away by the retreating wave. When the wave retreats, however, they return to the drift line. On the contrary, the sand hoppers are prompted to jump on the beating wave crest. By such an action, they get to the high parts of the shore. When the wave retreats, they move towards the drift line by jumping up-and-down. By repeating these characteristic behaviors, they do up-and-down migration with waves in the night. These are indicated in Fig.2. 3) Some experimental analyses were also performed to confirm the kind of sense these animals responded to the environments. In the laboratory experiment, the vibration sent out from the electric tuning fork(number of vibration was 50 hertz per minute)was used as the source of mechanical stimuli, the arrangement of which is shown in Fig. 3. The behavior observed in the laboratory experiments are represented in Figs. 4 and 5. It was proved that these animals had special sense to the vibrating stimuli caused by the electric tuning fork. From these laboratory experiments and some experiments executed at the natural habitat, it was supposed that the periodic behaviors in nature were evoked by the vibration of sand or shock given by the waves when they broke down and beat the shore. 4) When kept in the laboratory(first six days under normal day-night conditions and the successive eight days under constant darkness), the shore sowbug persisted its diurnal rhythmic activity for about two weeks, but after that time(again under normal day-night conditions)the activity became irregular and deceased on the 19th day from the beginning of the experiment. Whereas, the same activity of the sand hopper was modified within 3-5 days in the laboratory under normal day-night conditions, and deceased on the 6-7th day from the beginning of the experiment. The normality of the response to the mechanical stimuli mentioned above was decreased in accord with the change in the activity. 5) It was ascertained in the processes of above experiments and observations that the endogenous nature was participated in the exhibition of the diurnal rhythmic activity.
- 1958-07-30