| Project/Area Number |
11640640
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
生態
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| Research Institution | Natural History Museum and Institute, Chiba |
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Principal Investigator |
ASAKURA Akira Department of Animal Science, Natural History Museum and Institute, Chiba, Senior Researcher,, 動物学研究科, 上席研究員 (40250138)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1999: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | hermit crab / intertidal / interspecific competition / dominance / supeior competitor / aggressive behavior / shell fighting / zonation / 岩礁 / 競争 / 攻撃 / 防御 / 共存 / 潮問帯 / 貝殻 / 分布 / 貝殻利用 / 交尾行動 / 威嚇 |
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| Research Abstract |
Interspecific competition was investigated in three species of hermit crabs Pagurus lanuginosus, P.filholi, Clibanarius virescens, in which they are inhabiting intertidal rocky shores in Chiba. Habitats of these species were highly overlapped, but weak zonation patterns were recognized : P. filholi mainly inhabited the middle intertidal zone, with C. virescens occupying a lower and P. lanuginosus lowest zones. Shell utilization patterns were overlapped, all of these species using shells of Chlorostoma lischkei, Monodonta labio, Lunella coronata coreensis. Aggressive interaction was observed in laboratory. One individual from two species were put in a small aquaria and one individual was provided with a shell that aperture was artificially broken to promote aggressiveness and another was in natural state. The competitive superiors obtained shell from the inferiors by direct shell fighting. The attacker initially turned over the shell of the defender and then hold it with its ambulatory legs. At this moment, the defender completely withdrew into the shell. In this attitude, with shell apertures facing each other, the attacker inserted its chelipeds into the aperture hole of the defender's shell. The attacker then proceeded directly into rapping and get the defender's shell. C. virescens in broken shells got shells from P. filholi in 12 cases among 80 replicates(15%). P. lanuginosus with broken shells got shells from C. virescens in 2 among 72 replicates(3%). P. filholi in broken shells got shells from P. lanuginosus in 20 cases among 132 replicates (15%). P. lanuginosus with broken shells got shells from P. filholi :. 97 among 145 replicates(67%). Competitive hierarchy is (strongest first) : P. lanuginosus>C. virescens>P. filholi. This order coincidents with the order of habitat from lower to upper intertidal zones, suggesting the competitive dominant species occupies more comfortable areas.
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