ヤドカリの求殻行動と計測能力

概要

論文の詳細を見る
Analysis of Shell-searching behavior, readily shown by the land harmit-crabs, Coenobita regosus after removal of their snail shells was made on each successive step of behavior, and sensory factors controlling the behavioral events were investigated. Discrimination of size at the first step of behavior, i.e. orientation and approaching to objects, depended not on the absolute size but on the visual angle formed at the crab's eye. The shape of object was measured independently by vertical and horizontal factors. The crabs prefered more or less flat object while the crabs tended to select larger object. When a hermit-crab came in close vicinity of large object, and the visual angle formed at crabs eye exceeded a certain critical value, the crab tried to keep away from the object. Holding of the object occured immediately after the crab came in direct contact with the object. Clear optimum existed with regard to size, height and width of the object adequate for the initiation of the response in naked hermit-crab. The selective initiation of the holding response was due to the measuring activity of exteroceptive or proprioceptive mechanism of claws and/or other walking legs. The hermit-crab carrying the shell also turned, approached to and took hold of the target object. In no case optimum was found in the selection of both height and width, contrary to the case of the naked crabs. The tendency of the shell-bearing crab to select and seize taller and broader object will help the crab to climb up large trees or hills. A thread tie given to cephalothorax or abdomen was enough to switch over the abovementioned behavior pattern from naked type to shell-bearing type. The holding response of the naked hermit-crab was almost always followed by the insertion of claws, no matter how wide or narrow was the concavity. The crabs bearing unconfortable shells or a thread tied on the abdomen also behaved like naked crabs with respect to the claw-insertion response. During the process of claw-insertion, the size of concavity was measured by the proprioceptive activity of a pair of claws, working as measuring tools to take the dimension of the hole, into which the hermit-crab was to insert the abdomen. The left claw played a principal part in the measurement, although the right claw and, further, the second walking legs took compensatory part. A crab settled down in the concavity escaped, in a long run, from the hollow models, no matter how adequately shaped the model might be. What was important for the long-lasting stay in the hole was the movability of the shell model.
社団法人日本動物学会の論文
1968-09-15

ヤドカリの求殻行動と計測能力

スポンサーリンク

概要

著者

関連論文

スポンサーリンク