Abstract
Methods are described that allow a quantitative estimation of selective ingestion of sedimentary organic matter by deposit-feeding animals. The estimation can be made independently of any information of possible modes of selection. Animals need not be starved for a feeding trial, as is usual in other electivity studies. The protobranch bivalve N. annulata, when offered silt-clay sediment in which it was living, ingested sedimentary organic matter non-selectively.