In this work we have focused the study on single-entrance caves. These caves have neither the marked seasonality (due to the chimney effect) of the caves with two entrances, nor the complexity of the multi-entrance caves, nor the poor relations with the outside of the caves whose entrance is artificially closed. As single entrance is considered here a wide mouth through which can pass air (and the man who studies the cave). These caves are the least known from the climatic and dynamic point of view. In fact, caving has used the internal circulation of multi-entry caves since some decades to see if they are more extensive than it appears and to direct the searches for new galleries. Therefore, a vast scientific literature describes the ventilation mechanisms of these caves and the consequent thermal variations. Conversely, the lack of appreciable air circulation is considered by cavers as a clue to not extended cave, i.e. not interesting. However, from the biological point of view, in NW Italy the caves with single entrance are the most interesting: their more protected environment host many more endemic species.