Is hermit crab shell fight facilitated by predation risk-mediated sensory trapping?

2023 Fiscal Year Final Research Report

• Project/Area Number: 18K06416
• 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: Wakayama University
• Principal Investigator: Tsunenori Koga 和歌山大学, 教育学部, 教授 (50324984)
• Co-Investigator(Kenkyū-buntansha): 吉野 健児 国立水俣病総合研究センター, その他部局等, 室長 (40380290)
• Project Period (FY): 2018-04-01 – 2024-03-31
• Keywords: 感覚トラップ / ヤドカリ / 殻交換 / 捕食リスク

Outline of Final Research Achievements

In shell exchange of hermit crabs (a struggle for the shell), it is curious that the defender gives up and sheds the shell rather easily, even though the rapping attack by the attacker to deprive the shell of the opponent does not appear to be fierce. Therefore, we conducted experiments using two species of hermit crabs based on the hypothesis that the rapping attack functions as a sensory trap to deceive the defender as if he perceived attack from predators, and that the defender cannot resist and shed easily. The results showed that, as predicted, both species showed a significant tendency to give up their shells more easily in response to the attacker's rapping attack when the defender recognized the predation risk than when did not. However, we also realized that further experiments are needed to complete testing the hypothesis.

Free Research Field

進化行動生態学

Academic Significance and Societal Importance of the Research Achievements

生物界では広く食う・食われるの関係が見られ、同種個体の様々な生態に天敵の存在が影響することが知られる。例えば、配偶者や食べ物、棲み場所といった資源を巡る競争において、捕食リスクの有無により勝敗が逆転することがある。しかし、ヤドカリの殻交換（殻を巡る闘争）については、どういった個体が強いのか、またアタッカーのどんな攻撃がディフェンダーを効果的に追い出せるのか等について様々な研究が行われてきたものの、捕食者の影響を考慮した研究は世界的に皆無であった。本研究の成果は、捕食リスクの有無が殻闘争行動に影響することを示した世界初の研究となり、ヤドカリの生態の研究に新たな展開をもたらすことが期待される。