Is the waving of ocypodoid crabs sensory trap?

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K06841
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 45040:Ecology and environment-related
• Research Institution: Kumamoto University
• Principal Investigator: Henmi Yasuhisa 熊本大学, くまもと水循環・減災研究教育センター, 教授 (40304985)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: シオマネキ類 / waving / スナガニ類 / 求愛ディスプレイ / モデル選択実験 / 行動の進化 / 行動の起源 / 干潟

Outline of Final Research Achievements

During the breeding season, courting males of many ocypodoids (famously, fiddler crabs) perform claw-waving displays, in which they rhythmically raise, often extend, and lower their chelipeds when they are near their burrows. This conspicuous display sometimes attracts wandering (burrow-less) sexually receptive females to males' burrows where the crabs mate. However, since most of claw waving is not directed to a particular receiver, the display may also attract males and unreceptive females that are searching for new burrows, not mates. We showed that male claws and the claw waving of Austruca lactea and Ilyoplax pusilla may reveal to unintended receivers the locations of burrows that these crabs can use temporarily as refuges.

Free Research Field

動物行動学

Academic Significance and Societal Importance of the Research Achievements

スナガニ類のwavingは，科学者だけでなく，一般の人も興味を持つ，非常に目立つ行動である．しかし，wavingを行わない種類も多く，その起源や進化については不明な点が多かった．本研究は，ハサミモデルやそれをマイコンを使って動かすハサミロボットを用い，それに対する放浪個体（オスや成熟度の異なるメス）の誘引の有無を実験的に調べ，『wavingは，巣穴を持たない個体（放浪個体）が一時的に他個体（巣穴個体）の巣穴に逃げ込む時に，ハサミの動きという視覚的刺激に誘引されたのが起源』であることを示した．