Substratwahlversuche an Pisidium casertanum und Pisidium amnicum (Bivalvia)

Two species of Sphaeriidae ( Pisidium casertanum and P. amnicum) could choose between two different substrates (coarse-grained and finely-grained sand, mud and substrate of leaves respectively). Significant differences in behaviour concerning different substrates are discussed. It is concluded that these findings are in contradiction to observations of natural behavior which demonstrates that experiments in laboratory conditions can lead to doubtful results.