Distribution in relation to life history in the directdeveloping gastropod Batillaria cumingi (Batillariidae) on two shores of contrasting substrata |
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Authors: | Adachi Naoko; Wada Keiji |
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Institution: |
Department of Biological Science, Faculty of Science, Nara Womenís University,
Kitauoya-nishimachi, Nara 630-8506, Japan |
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Abstract: | Population structure and spatial distribution with growth ofthe direct-developing
gastropod, Batillaria cumingi, were investigatedon two shores of differing substrata.
Sand-mud shore and rockyshore populations differed in size structure; first-year snailswere ca. 7
mm in shell length (SL) in both populations, whereassecond-year snails, merging with older
cohorts, measured 1525mm SL in the sand-mud shore population and ca. 15 mm SL in
therocky shore population. Egg distribution matched adult distributionin the sand-mud shore
population, but was more restricted thanthat of adults in the rocky shore population. The
distributionof newly-hatched juveniles (01 mm SL) was restricted inboth populations,
but the growth stage at which snails extendedtheir distribution differed between the two
populations; 12.5mm SL on the sand-mud shore and 5 mm SL on the rocky shore.
Floatingachieved by early juveniles (ca. 2 mm SL), was commonly observedin the sand-mud
population, but rarely in the rocky shore population.The sudden expansion in distribution of the
12.5 mm SLgrowth stage in the sand-mud shore population is consideredto have been
caused by floating, while expansion of the distributionof older growth stages (>5 mm SL) in
the rocky shore populationprobably occurs by crawling. (Received 13 May 1998; accepted 25 August 1998) |
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Keywords: | |
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