"It is beneficial for males to mate as often as possible, since this is the only way in which they can influence the number of offspring they father. But it is costly for the females to mate often, and this is important for them in surviving during the period they are carrying offspring."
The females of most species of snail excrete a substance in their mucous trails that enables males to find them more easily, since they can distinguish between trails from females and those from other males. The males follow the mucous trails laid down by females in order to find a partner for mating. However, the females of one of the species studied (Littorina saxatilis) have stopped labelling their mucous trails.