Particle selection and regulation of particle uptake by the slipper limpet Crepipatella fecunda

We established the role of the pallial filter in the suspension-feeding slipper limpet Crepipatella fecunda (Gastropoda, Calyptraeidae), which inhabits coastal areas of southern Chile characterised by sediment resuspension resulting from tidal forces. We determined that this spe- cies is capable of qualitative and quantitative pre-ingestive selection of particles. We exposed individual limpets to diets composed of a mixture of sediment and microalgae and measured the particle concentrations in the inhalent region, the infrabranchial cavity and the exhalent region, allowing us to derive an electivity index individually for the pallial filter and the gill. At a particle concentration at which pseudofaeces are always produced, and regardless of the proportion of sediment in the diet, the pallial filter selectively removed sediment (inorganic) material from sus- pension and diverted it into the lateral canal of the mantle for rejection. Qualitative particle selec- tion on the gill was observed when the proportion of microalgae in the diet was low and micro- algae were preferentially retained. When the diet was composed entirely of sediment, the gill retained only 15% of the suspended particles. The gill is more a collector than a selector of parti- cles, while the pallial filter regulates the concentration of particles entering the pallial cavity and increases the nutritional quality of the suspension available for removal by the gill, thereby par- tially compensating for the high proportions of inorganic matter in the resuspended sediment which the limpet encounters during the tidal cycle, especially in the periods immediately before exposure to air and after reimmersion.