Bulletin of the Hiroshima University Museum Issue 12
2020-12-25 発行

瀬戸内海におけるムシロガイ科腹足類3種に共生するヒドロ虫類の生態学的研究

Ecological study of three hydrozoan species associated with three different nassariid gastropod species in the Seto Inland Sea
YONETANI, Mari
NAMIKAWA, Hiroshi
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abstract
Polyps of three hydrozoan species associated with three gastropod species of the family Nassariidae were observed in the Seto Inland Sea, Japan: (1) Leuckartiara sp. with Nassarius festivus occurring in the intertidal zone as well as (2) Cytaeis uchidae with N. livescens and (3) Stylactaria misakiensis with N. japonicus occurring in the sublittoral zone. Each hydrozoan species was highly host-specific, without any exceptional combination. The host utilization rates of the three hydrozoan species were markedly different; as such, the host utilization rate of Leuckartiara sp. occurring in the intertidal zone was less than 10%, whereas that of C. uchidae and S. misakiensis occurring in the subtidal zone ranged from 84% to 94%. Sexual reproduction was limited to summers in Leuckartiara sp. and C. uchidae, but it occurred yearround in S. misakiensis. The burying behavior of host shells differed among the three species; specifically, the intertidal N. festivus was buried in the sediments for over 20 h a day, while the subtidal C. uchidae and S. misakiensis were buried for less than 7 h a day. The ecological differences among the examined hydrozoan species associated with specific nassarrid hosts likely strengthen their niche segregation.
subject
囲皮
宿主特異性
生殖体
潜砂行動
プラヌラ
ポリプ
Burial behavior
Gonophore
Host specificity
Periderm
Planula
Polyp
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