AICME II abstracts
Mathematical aspects of fragmentation and ...
Interactions among individuals in a fish school based on measured parameters of natural fish school and analytical model Yoshinobu Inada1 , Keiji Kawachi2 and Hao Liu3 . Schooling motion of two species of fish (Bearded silverside, or Atherion elymus; and Hardyhead silverside, or Atherinomorus lacunosus) was studied focusing on two types of motion: approaching motion, where an individual moves toward the position of its neighbors, and parallel orientating motion, where an individual adjusts its body direction to be parallel with those of its neighbor’s body direction. Correlation of measured motion parameters (position, body direction, and moving direction) among individuals was used to determine which motion each individual was executing. Most individuals throughout the school usually executed parallel orientating motion, and individuals in the middle or rear part of the school simultaneously executed parallel orientating and approaching motions. Conspicuous differences between the two motions were evident in the direction of interacting neighbors from the body direction of an individual and in the time delay of an individual from the motion of interacting neighbors, but not in the number of interacting neighbors or in the distance to interacting neighbors. These similarities and differences between the two motions depend on the sensitivity of a fish’s sensory organs, such as eyes and also depend on the chain of interaction among individuals 1
Japan Science and Technology Corporation (JST), Department of Electronics & Mechanical Engineering, Faculty of Engineering, Chiba University, 1-33 Yayoi-cho, Inageku, Chiba 263-8522, Japan (e-mail:
[email protected]). 2 Department of Aeronautics and Astronautics, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan (e-mail:
[email protected]). 3 Department of Electronics & Mechanical Engineering, Faculty of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan (e-mail:
[email protected]).
11-Ina-a
Mathematical aspects of fragmentation and ...
AICME II abstracts
where the interaction in the vicinity of individual spreads to surrounding neighbors accompanied by time delay. The results of observation provide insight for analytical study of schooling motion. Analytical model to simulate individual motion in the school was designed based on approaching motion and parallel orientating motion, and was used to study the relationship between local interaction among individuals and global properties of schooling motion. Individual motion parameters that control the intensity of approaching or parallel orientating motion affect the global properties of school, such as adhesiveness, polarity, expansion, or aspect ratio of school. Thus, the study clarified the effects of individual motion property on the schooling motion both quantitatively and qualitatively using the model based on measured parameters of natural fish school.
References [1] Huth, A. & C. Wissel, 1992, The simulation of the movement of fish schools, J. theor. Biol., 156, 365-385. [2] Inada, Y & K. Kawachi, 2002, Order and Flexibility in the Motion of Fish Schools, J. theor. Biol., 214(3), 371-387. [3] Parrish, J.K. & L. Edelstein-Keshet, 1999, Complexity, Pattern, and Evolutionary Trade-Offs in Animal Aggregation, Science, 284, 99-101. [4] Partridge, B. L. & T. J. Pitcher, 1980, The sensory basis of fish schools: relative role of lateral line and vision, J. comp. Physiol., 135, 315-325.
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