Slugs are simply terrestrial snails without shells. The yellow slug (Limax flavus) shown above is one of several species found in our local gardens. A native of Europe, this slug has been introduced around the world and is often found associated with humans, such as in gardens or damp cellars. It is usually nocturnal, but can be encountered outdoors during rainy weather.
The hole on the side of the animal's mantle is a breathing pore, or pneumostome, which allows air into the lung. The slug can keep it closed to prevent dehydration, but it must open it to breathe. This is one of the reasons that slugs are not active during very dry weather. The larger pair of tentacles are called the optical tentacles because they have the eyes, while the oral tentacles are the smaller pair below which allow for the sense of smell. The mucus that covers the body is a pale yellowish color, while that produced by the foot is clear.
Slugs feed on a variety of organic matter, including plant and animal remains, as well as fungus and living plants.