Our first hypothesis (higher survival in substrata that keep higher moisture) was rejected because leaf litter showed the high-est moisture but also the lowest survival. This may be explained because of the faster desiccations rate found in this material. In fact the low survival found in leaf litter can be compared with that found in a previous study where animals were air-exposed (Alonso andCastro-Díez, 2012b). Therefore, the leaf litter scenario was similar to an air exposure, as animals were not completely covered by leaf litter. By contrast, in the clay and sediment substrata snails were completely covered by the substrata, which may create a more protective microenvironment against animal desiccation, in spite of the lower moisture of those materials. Additionally, the probabil-ities to be detached during transport in leaf litter could be higher than in sediment or clay.