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博士後期課程２年生の吉川晟弘 さんが論文を発表されました。おめでとうございます。
Morphology and Habitats of the Hermit-Crab-Associated
Calyptraeid Gastropod Ergaea walshi
Akihiro Yoshikawa, Ryutaro Goto, and Akira Asakura
ZOOLOGICAL SCIENCE 35: 494–504 (2018)
これはヤドカリが利用している巻貝の貝殻の内側につく珍しい貝の仲間の生態に関するものです。巻貝の仲間ですが、平たい笠型の形をしています。
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| 写真：吉川晟弘 Copyright |
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| 写真：吉川晟弘 Copyright |
Ergaea walshi, a gastropod with a markedly flat shell, often lives inside empty snail shells occupied by hermit crabs. We investigated its lifestyle, shell growth pattern, and habitat preference for host hermit crabs and host snail shells. Four hundred sixteen snail shells, including 363 shells with hermit crabs and 53 empty shells, were collected from intertidal zones of sandy and muddy flats around Kii Peninsula, Japan. The specimens comprised seven hermit crab species occupying 24 shell species; E. walshi was harbored in 13.2% of snail shells with hermit crabs and 17.0% of those without hermit crabs. Although no preference was detected for particular species of hermit crab or snail shell, E. walshi preferred to live inside of snail shells with wider apertures used by comparatively bigger hermit crabs. This suggests that the occurrence of E. walshi was influenced by host size rather than host species. When looking at growth patterns, we found that the attached shell portion of E. walshi continued to be enlarged horizontally, while growth in shell height slowed at approximately 5.0 mm. The conspicuously flattened shell of E. walshi is considered as a growth pattern for adapting to the narrow space within the snail shell occupied by hermit crabs. Consistent with this idea, our comparison of shell growth patterns in 23 calyptraeid species showed that shell of E. walshi is the flattest in this family.