We were hanging out in the Wonderopolis garden the other day and overheard two earthworms named Larry and Moe telling jokes:
Larry: What's a slug?
Moe: I don't know.
Larry: A snail with a housing problem!
Moe: Ha! That's a good one, Larry.
Larry: Hey Moe, what should you do if you see two snails fighting?
Moe: I have no clue, Larry.
Larry: Leave them alone and let them slug it out!
Moe: You're on a roll today, Larry.
Snails and slugs are both part of the same class of creatures called gastropods. Gastropod comes from the Greek words gastros (stomach) and podos (foot). If you've ever seen a snail in an aquarium eating as it moves slowly along the glass, you probably understand why “stomach foot" might be an appropriate name!
The most obvious difference between snails and slugs is the fact that snails have shells. A snail's shell is like a home it carries around on its back. Slugs, on the other hand, have no shell. Otherwise, snails and slugs are remarkably similar.
Their only other differences are in habitat and behavior, but these differences are the result of the fact that snails have shells and slugs don't. Without those big shells to carry around, slugs can squeeze themselves into many different habitats that snails can't. For example, you may find slugs under loose bark on trees or stones and logs on the ground — places that snails could never go with their shells.
If you spend much time in a garden or the great outdoors, you may be more familiar with snails and slugs that live on land. As they move along, you've probably noticed that they often leave behind a slimy trail.
That slime is called mucus. Snails and slugs make mucus so that they can move on the ground. The mucus keeps their bodies from losing moisture to the dry soil beneath them. It also protects them from being cut by sharp objects in the soil.
Unfortunately, most gardeners view snails and slugs as pests. Snails and slugs can completely destroy gardens by eating plants and fruits, including their roots, leaves, and stems. Gardeners sometimes use salt or other chemicals to dry out and drive away snails and slugs.
Some people even turn the tables on snails and slugs and eat them! All over the world, snails and slugs are a source of protein in the diets of many people. They're even considered a delicacy in some places. For example, in France, escargot is a specialty dish made of a certain type of land snail.
Because of their small size and the way they move, snails and slugs are naturally slow-moving creatures. If it takes you a long time to do your homework, your parents may accuse you of moving “at a snail's pace," for example. Likewise, in today's modern world of instant communication via e-mail, regular mail via the postal service can take days and is now sometimes referred to as “snail mail."