Snails take male role in sex when released from solitary confinement

The great pond snail prefers to play the man after being locked up and denied calcium, new research finds. Flickr/Roy Stead.

Pond snails kept in solitary confinement and starved of calcium for more than a week prefer to take the male role during post-liberation sex, researchers from the University of Calgary have found.

Using adult specimens of the great pond snail (Lymnaea stagnalis), the team from the university’s Hotchkiss Brain Institute subjected the hapless molluscs to a variety of deprivation experiments in order to explore the effects on cognition.

In findings published yesterday in the Journal of Experiemental Biology, the authors report that pond snails being hermaphrodites, “mating is usually reciprocal, [but] isolation of adults for 8 days results in individuals preferentially performing the male role.”

During their eight-day stretch of solitary confinement the incarcerated snails would have been able to sense each other, the authors report: “Alteration of copulatory behaviour occurs after snails were isolated using perforated jars maintained within the same aquaria, hence allowing any waterborne chemicals to pass freely between individuals, but not allowing direct contact.”

The paper, “Social snails: the effect of social isolation on cognition is dependent on environmental context”, does not describe what happens when pairs of newly released pond snails attempt to mate. However, the authors write that in their calcium-deprived state, the snails may have preferred to take the male role in sex because it is easier.

“Performing primarily as a male during copulation … and reducing [the subsequent] egg-laying behaviour … following isolation for 8 days will significantly reduce the calcium requirements of an individual snail,” the researchers report.

The authors also found that “social isolation enhanced long-term memory formation in snails exposed to low-calcium conditions, a stress that blocks blocks memory formation in groups”.

Yet, long-memory function in snails was blocked when the experimenters tormented the isolated snails by adding chemical signals to the water that indicated the presence of crayfish - a predator of the great pond snail.

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