Gastric emptying; food consumption and feeding periodicity of Rapana venosa were investigated under laboratory condition's and in the field respectively. Gastric emptying was best described by an exponential function, that was independent-of meal size and the range of animal size when rapana were fed on fresh mussel. The fresh mussel (0.92-2.19 g) was,fully digested by an average of 47 g rapana within the 6-8 hours. No change in feeding intensity was detected over 24 hours suggesting that rapana feed continioussly. Using gastric emptying rates from the laboratory studies, the data obtained from the field was converted to the food consumption estimates and concluded that an average of 50 g rapana in the eastern Black Sea marine ecossystem consume 0.17-0.30 g. mussel in a day, meaning that rapana in the eastern Black Sea marine ecosystem may cause an important predatory impact on the mussel beds.