A Method for Breeding and Studying Freshwater Snails Under Continuous Water Change, With Some Remarks On Growth and Reproduction in Lymnaea Stagnalis (L.)

Abstract

Many experimental studies of freshwater snails are hampered by the fact that the medium in which the animals are kept should be renewed repeatedly. This treatment will affect physiological processes (e.g., oviposition; cf. TIMMERMANS, 1959; VAN DER STEEN, 1967) to a con- siderable extent. Indeed, when periodic water change is applied, effects of other external factors to be studied can be obscured. More- over, the variability in experiments involving serial observation periods is then increased. VAN DER STEEN (1967), investigating the effects of environment on reproduction in Lymnaea stagnalis, applied continuous water change to avoid the above mentioned difficulties. The relevant experimental set-up was realized by keeping snails in perforated glass jars which were standing in continuously changed water. In the present paper an improved set-up for continuous water change is described. An experiment on the culture of Lymnaea stagnalis under continuous water change is discussed. This experiment also yielded some data on growth and reproduction.