Does Ayu have laterality?

2005 Fiscal Year Final Research Report Summary

• Project/Area Number: 16380134
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: General fisheries
• Research Institution: Kochi University
• Principal Investigator: YAMAOKA Kosaku Kochi University, Graduate School of Kuroshio Science, Professor, 大学院黒潮圏海洋科学研究科, 教授 (20200587)
• Co-Investigator(Kenkyū-buntansha): HORI Michio Kyoto University, Graduate School of Science, Professor, 大学院理学研究科, 教授 (40112552) ; SEKI Shingo Kochi University, Faculty of Agriculture, Associate Professor, 農学部栽培漁業学科, 助教授 (20216518)
• Project Period (FY): 2004 – 2005
• Keywords: Ayu / Handedness / Feeding behavior / Morphology / Genetic features / Artificial seedling / Lake Biwa population / Marine population

Research Abstract

We observed the feeding behavior of 81 individuals of 3 strains of ayu under artificial current water condition. Three strains were fish of artificial seedlings, of Lake Biwa population and of marine population. The observation was conducted 100 times per fish per day. After observation, they were numbed with ice water, and then hung with the caudal up in 10% formalin solution in a bucket. The reason why we performed such a troublesome method is to exclude every force affecting body shape, mainly the body axis, before rigor mortis except the gravity. We used the location of the of lower jaw ariticulation as the character for judging the laterality. We also used the curve of the body axis for judging the laterality. Fifty-two individuals showed significant difference in the frequency between rightward and leftward feeding bites (as: r.9,l.10, LB: r.10,l.10, mp: r.7,l.6). No difference could be found among the 3 strains about the feeding behavior. Every rightward biting individuals showed the body curve of reverse C shape from above and vice versa. Rightward biting individuals have morphological left-handedness and leftward biting ones have morphological right-handedness. So there is a reverse relation between behavioral handedness and morphological handedness in ayu. This fact suggests that there are intimate interrelationships among the position of lower jaw joint, body curve and feeding behavior. For the pectoral fin, 61 individuals had shorter length at the body side of handedness. These facts suggest that there is an intimate interrelationship between morphological handedness and paired fins length.