SNAILS usually destroy gardens, but one species creates its own. The marsh periwinkle, Littoraria irrorata, lives exclusively among the salt marsh grasses of the US eastern seaboard and cultivates fungus. This habit may be the secret of its evolutionary success.
The snails have a long-standing reputation for munching marsh grass, all the way from New England to Texas, and textbooks say they live off the stuff. But Brian Silliman of the University of Georgia, Athens, has discovered that their assiduous munching is in fact designed to create holes in the leaves, exposing the inner tissue to invasion by fungal spores…
