[Observation on moving patterns of Oncomelania snails in rivers and canals].

Objective: To understand the moving patterns of Oncomelania snails, intermediate host of S. japonicum, in the water bodies.

Methods: Based on the biological features of the snails, methods and techniques in relation to hydraulics and silt engineering were adopted to investigate the active scrawl ability and passive movement of the snails.

Results And Conclusion: The scrawl speed of the snails themselves was very low, 2.45 mm per minute only. The active movement in the water current was therefore almost negligible. The major moving patterns of the snails in rivers and canals were that: 1. Snails adsorbed on different kinds of carriers drifted on the water. 2. Snails suspended on the water and drifted with the current, these were the young snails under 7 weeks of age. Adult snail showed a strong ability of adhesion, 12 times higher than its body weight.