Lady beach snails can say, "Not now, I have a headache" to romantic males, according to studies conducted this summer by scientists at the University of Gothenburg's Department of Marine Ecology, Göteborg University in Sweden.

The female snails also have a more foolproof method of spurning the affectionate advances of suitors than merely wrinkling brows, frowning and holding a hand to their foreheads: they fool the guys into thinking they are also men, rather than women.


The trick takes advantage of the habit of ladies in the species Littorina sax of secreting a slimy trail behind where they slither so that the so inclined guys can more easily follow and find them. On the other hand, the males, who also secrete a trail, leave mucus of a different consistency. By not leaving an effeminate aphrodisiac like substance, females confuse males who are left only with their own gender's slime to slither after.

"This can seem strange, because females ought to be interested in mating. But in this study, we show that sexual encounters are costly for females when they have already had more than sufficient matings to fertilize all their eggs," said Kerstin Johannesson, professor of marine ecology at Gothenburg University.

In previous research nearby on the island of Tjärnö, scientists found that a female can bear the offspring from as man was 20 males. Evolution favors anonymous females who mask their tracks, thereby enduring significantly fewer matings that their more licentious sisters of their species and increasing their chances of survival.

"Males benefit from mating as many times as possible, because this is their only way to influence how many offspring they have. For females, it is costly to mate so often because it takes more to survive while they are carrying the offspring," noted Johannesson.

However, the research team of Johannesson, in collaboration with Sara Saltin, Iris Duranovic, Jon Havenhand and Per Jonsson, pointed out that this is one of the few instances in animals of a sexual conflict in which the females try to hide their gender.