The shorter pair of tentacles is used for smelling and sensory perception. Both land snails and slugs are considered pests by most gardeners. Land snails often make their way into heavily farmed areas after a rain shower. A capable traveler, land snails can slither their way across areas as narrow as the edge of a piece of paper, and have been known to do serious, long term damage to green crops. Slug trails are most commonly long and continuous.
Snails travel long distances, as well, but often leave a broken trail.
Freshwater snails are usually carried by birds' feet, on wind blown sticks or leaves, and during rainstorms. Those freshwater snails which end up out of their natural territory are often a problem to livestock and other warm blooded animals, as this species is a host to the flatworm. When snails are disturbed or fear danger, they pull themselves back into their shell. Once inside, the snail seals the entrance of the shell to prevent itself from drying up. Snails are most active at night or on cloudy, high humidity days.