Particle Selection in Suspension-Feeding Bivalves

Abstract
Particle selection was studied in 10 spp. of suspension-feeding bivalves by comparing the proportion of algae in the pseudofeces with that in the surrounding water. All species examined exhibited particle selection, but with different efficiencies. Spisula subtruncata was most efficient, followed, in decreasing order of efficiency, by Corbula gibba, Mytilus edulis (from Wadden Sea [Netherlands]), Acanthocardia echinata, Aequipecten opercularis, Musculus niger, Crassostrea gigas, Mya arenaria, Cerastoderma edule, M. edulis (from Oresund [Sweden, Denmark]) and Arctica islandica. Selection efficiency correlated with the size of the labial palps. Particles rejected as pseudofeces were embedded in mucus; ingested particles were always in free suspension in M. edulis. Apparently, different particles have different probabilities of being trapped in mucus, and thus rejected as pseudofeces. The properties which determine this probability are unknown.