Slugs (from the mollusk family)
Slugs play and important role in the environment because of their tendency to eat dead leaves, fungi, and decaying vegetable material. But when they start feeding of living plants, such as the tomato plant is when many gardeners get fed up. Slugs tend to leave slime where they have been and eat the tomato plant leaves. The slime left behind is basically a trail in which other slugs will recognize and follow. Due to this, when you have one slug in your garden, you better get rid of it quick, because typically it means many are to come! In a garden, slugs are also destructive to cabbage, lettuce, turnips, and carrots.