著者

岩田 清二 渡辺 宗孝

出版者

社団法人日本動物学会

雑誌

動物学雑誌 (ISSN:00445118)

巻号頁・発行日

vol.66, no.12, pp.464-467, 1957-12-15

---

A terrestrial isopod pill-bug, Armadillidium vulgare, shows a positive thigmotactic behavior in a L-T maze as shown in Fig. 1. The so-called alternate turning response of this animal seems to be a natural result of this thigmotaxis as described in the following lines. The animals started from the starting box continue to progress until they come to the L-point and knock against the wall which blocks their straight passage, and there they are forced to turn to the right and run along the left wall of the straight path keeping close contact with it. This causes an oblique progression somewhat leftwards at T-point after they have been freed from the contact with the wall, perhaps owing to the homostrophic reflex. In this way, they strike against the distal wall of the T-point with their right body-sides. Further progress ensues keeping the contact of this body-side with the distal wall, resulting in the leftward turning. This is a typical behavior observed in the majority of the animals in the maze, indicating that the basic mechanism of behavior is thigmotaxis. As is stated above, the animals found in the left area at the end of the straight path turn to the left alternating with the preceding rightward turning at L-point. However, those found exceptionally in the right area turn to the right agreeing with the preceding. This fact seems to indicate that the turning is directly based on the mechanism depending upon thigmotaxis (homostrophic reflex) rather than what is predicted by the place avoidance theory or the reactive inhibition theory, both of which claim that the direction of turning at T-point is determined by that in preceding turn.