A Little Bit More
Although slugs are really impressive animals, their damage in gardens coupled with their slimy, mucous production when handled, means they’re unloved by most people. If you’ve ever tried picking one up in your hands, you know that they can produce a very sticky, thick mucous that is extremely difficult to remove. Mucous production is a defensive measure that works well against most predators.
Shelled mollusks (clams and snails) have a big advantage with their shells. Shells offer their owners protection from both predation and the elements. Slugs however, have evolved away from shell production yet have a distinct advantage over shelled snails – they’re able to live in areas of the country devoid of enough calcium for shell creation.
Mucous production makes it possible for slugs, and snails for that matter, to move about on land – they move on a thin coating of slippery mucous. This coating is so effective that a slug can crawl on the edge of a razor and not be hurt. Mucous trails are often easy to see on garden plants and flowers in the early morning where slugs and snails are common.
Although there are many remedies for ridding garden slugs, I find that working “with” slug natural tendencies, is an easy, chemical-free way to eliminate these hungry pests. Since slugs are prone to drying, they seek shelter under all kinds of rocks, plants, and boards during the day. By simply placing boards around your garden plants, one can lift the boards each day and remove those slugs hiding there – you’ll quickly eliminate most of your slugs.
Activities
Science – Slug It Out
Objectives: Close observation of slugs
Materials: Terrarium, slug, assorted plant material
One of the best ways to understand an animal, is to live with it! Have one or two of your students that have access to a garden/flower bed, try to find a couple of slugs to bring into your classroom.
You can set up a terrarium in the classroom in a dark corner of the room, place some rocks, small branches, and plant material in a covered container and introduce one or more slugs. You’ll need to keep things on the moist side but not so moist that any fungus begins to grow (a water spritzer can be used when necessary).
Slugs feed on a wide variety of plants so you may want to bring in different kinds of plants to see what they prefer. Any leafy vegetables will work plus dandelion greens, plantain leaves and any other weedy plants from outside. Not all of your offerings will be acceptable so your students can see which ones are preferred. Slugs have a scraping mouthpart and leave behind very obvious “holes” in the plants on which they feed so this should make it easy to see what they’re eating. If the terrarium is on the moist side, and not too brightly lit, your slugs should be active during daylight hours so all can watch their activity.
Some questions you may want to pursue:
1. Does the slug prefer to be in the lightest area or darkest area of its container?
2. Does the slug “respond to” your hand if it moves closely (don’t touch) across its head?
3. Offer different foods and see if it has any preferences (spinach, dandelion leaves, lettuce, carrot, mushroom, etc)?
4. If you gently touch the slug, how does it react?
Once you’ve all had a chance to get some good looks at these animals, they can be returned to their original location and released.
Key Concepts
Adaptations and Diversity, Identification, Structures and Functions
Questions
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