In surveys conducted along 2,000 kilometers of salt marshes on the southern U.S. shoreline, the researchers observed that the snail, Littoraria irrorata, actively grazes a live salt-marsh cordgrass. As the snail crawls along the grass surface, it scrapes grass tissue with its band of saw-like teeth and creates longitudinal cuts in leaf surfaces, making a much larger meal possible. While it travels, the snail also deposits feces laden with fungal spores and nutrients into the sensitive inner-tissue of the leaf, effectively stimulating and fertilizing fungal crops.
The result of snail grazing on marsh grass surface is an infestation of fungi, a major diet component for the snail, and the slowing of marsh grass growth.
"In its manner of manipulating fungi, the snail is conducting a low-level form of food production," said lead scientist Brian Silliman, an ecology and evolutionary biology doctoral candidate at Brown University. "This is fungal farming in a completely new group (phylum) of organisms and the first demonstration in the marine environment."
This method of agriculture called "fungiculture" was thought to occur only in three distinct insect lineages, including certain ants, termites and beetles. The development of fungus-growing behavior has enabled these insects to rise to major ecological importance in land communities where they can strongly affect ecosystem process and community structure through their farming activities.