Snail trail tale

Most female snails excrete a substance in their mucous trails that enables males to follow them in order to find a partner for mating. However, scientists at the University of Gothenburg have shown that females of the rough periwinkle (Littorina saxatilis) have stopped labelling their mucous trails, thereby concealing their gender identity.

The consequence of this for the females is, apparently, that they mate less frequently, since the males often follow the trails of other males and therefore spend twice as long looking for a female.

Though it would appear to be in the females’ interests to mate often, this is actually costly for them, say the researchers, because they already mate more than is required to fertilise all their eggs. Females that mate less often than other females have a greater chance of surviving.

For males, on the other hand, it is beneficial to mate as often as possible, since this is the only way they can influence the number of offspring they father.

Such “sexual conflicts of interest” can arise in various situations, and this is one of few examples of a conflict in which females try to hide their gender.