Journal Molluscan Studies Advance Access published online on December 10, 2007
Journal of Molluscan Studies, doi:10.1093/mollus/eym043
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SUSPENSION FEEDING AND KLEPTOPARASITISM WITHIN THE GENUS TRICHOTROPIS (GASTROPODA: CAPULIDAE)
Department of Biology, Muhlenberg College, 2400 W. Chew St., Allentown, PA 18104, USA
Correspondence: E.V. Iyenger; e-mail: iyengar{at}muhlenberg.edu
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The marine gastropod Trichotropis cancellata is a facultative kleptoparasite, either suspension feeding or parasitically stealing food from tube-dwelling polychaete worms. To determine whether conclusions drawn from long-term studies in the San Juan Islands, Washington, about the relative importance of suspension feeding and kleptoparasitism can be applied generally to T. cancellata across its biogeographic range, I expanded earlier studies to Alaska and British Columbia. Kleptoparasitism is pervasive throughout the range of T. cancellata, occurring with equal frequency throughout the areas studied. The average density and size of worm hosts are relatively constant across this range. Snail and worm densities are not significantly correlated at the larger scale of site (averaged over nearby sampling locations clustered around a city), but are correlated at the smaller local scale (within a sampling location). Larger worms do not support more snails. The abundance of uninfected worm hosts is usually not limiting, except potentially in some sampling locations in southwest Alaska where the use of a novel host (a holothurian) may be the result of low densities of uninfected worms. Additionally, I documented the feeding behaviours of other trichotropid species in these regions. Trichotropis conica is the second confirmed kleptoparasite within the genus Trichotropis, with kleptoparasitism as frequent in this species as in T. cancellata. Like T. cancellata, all sizes observed of T. conica are kleptoparasites. On the other hand, Trichotropis insignis is an obligate suspension feeder. Further studies are needed to determine exactly how many times this behaviour has arisen and been lost in Capulidae and related families.
(Received 31 May 2007; accepted 19 October 2007)