Creature Feature: Garden Slug (Arion hortensis)
By CG Science Editor Emma Dean
Like many OU students, slugs are nocturnal, preferring the cool of night to the daytime. However, slugs stick to damp, dark areas beneath things like rocks and boards. In fact, slugs prefer to lay their eggs in these regions as well as beneath a layer of leaves. The oval-shaped, white eggs only hatch when the conditions are right, meaning moist—even if it means waiting around years later.
Slugs play an important role in ecology by eating decomposing vegetation, although gardeners often consider them to be pests. However, there are some plants that repel slugs such as corn, daffodils and pumpkins.
Evidence of the presence of slugs is a slimy substance. The substance helps slugs to move as well as protects them from sharp rocks, twigs and other obstacles in their way. Each slug has a unique slime and so it can follow its trail from the night before. Slugs often follow each other’s trails in search of food.
Slugs creep along by contracting a series of muscles on the underside of the body. The body, or foot, is actually a huge muscle itself. The slug is a special kind of mollusk, along with oysters and snails, called a gastropod, which is the second largest class in the animal kingdom. Gastropod also means “stomach foot.”
Not only are slugs invertebrates and without backbones, but they are also without any bones at all. From this muscle of a body are light-sensitive eyes that are positioned on a long tentacle at the top of the head. Extending downward, and used for feeling and smelling, are shorter tentacles. Slugs breath through the respiratory pore which is a tiny hole on the right side of their bodies. A slug can also absorb oxygen with its body directly from the atmosphere in addition to breathing through the respiratory pore.
- There are over 40 species of slugs in the United States.
- The biggest slug in the United States is the banana slug which can grow to be nearly a foot long.
- Slugs dislike hot weather and consequently are most active in the spring and fall.
- Slugs can live up to six years.
- Snails have a special organ called a radula helps to grind up food with tiny protrusions.
- Slug slime absorbs water which makes it difficult to wash off your hands.
- Slugs are hermaphrodites with both male and female reproductive systems.
- Slugs can stretch to 20 times their normal length in order to squeeze through small openings.