Study on sociality of octopus at Octopolis specifically located in the Ryukyu Archipelago

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K19348
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 45:Biology at organismal to population levels and anthropology, and related fields
• Research Institution: University of the Ryukyus
• Principal Investigator: Ikeda Yuzuru 琉球大学, 理学部, 教授 (30342744)
• Project Period (FY): 2022-06-30 – 2024-03-31
• Keywords: タコ / 社会 / 脳 / 琉球列島

Outline of Final Research Achievements

This study aimed to investigate, based on field survey, state of Octopolis, a site with numerous octopuses exists, at the coast of the Ryukyu Archipelago, and to compare social behavior with brain anatomy of octopuses what were encountered at Octopolis. Coast at Okinawa Island were surveyed, and eight species of octopus were found. Among them, Octopus laqueus was the dominant species. Mating, intraspecific interactions, and interspecific interactions were observed. For brain anatomy, O. laqueus were observed, and some lobes were identified. Each lobe varies its volume and it likely to relates sociality and habitat of O. laqueus.

Free Research Field

動物行動学

Academic Significance and Societal Importance of the Research Achievements

本研究で調査したオクトポリスは広大であること、それは琉球列島という特異な場所で成立することを示した点で意義深い。また、そこに生息するソデフリダコは、顕著な社会性を示す種であり、それが脳構造にも反映されていることを示し得たことで、タコ類は単独性という定説に再考を促す契機となった。一方、タコ類は水産物として重要であるが、本研究の成果は水産資源としてのタコ類の動態についても有用な情報を提供した。