Handbook of Nature-Study · Lesson CVI · Topic 17: Snail, earthworm and crayfish
106. The garden snail
Goal: Your child can describe how a snail moves on its one foot, where its eyes and feelers are, and how its shell grows.
You'll need
- A snail or two from the garden (after rain, under boards or leaves)
- A clear jar or plastic box with damp soil, moss and a lettuce leaf, and a cloth cover
- A piece of clear glass or plastic
- A hand lens (magnifying glass)
- A nature notebook and a pencil (colored pencils if you have them)
What's in the book
Section VII of the book, "Other Invertebrate-Animal Study", opens with Comstock's story of the snail: its wonderful single foot, its slime track, its eyes on stalks, its rasping tongue, its breathing hole and its spiral shell. Then Lesson CVI's leading thought, a method with directions for a snailery, eleven questions, and a poem.
The lesson, step by step
When and where
Spring to fall, on damp mornings and evenings or after rain. Look under boards, stones, flowerpots and leaves in gardens.
Safety first
Snails and slugs can carry germs and parasites. Wash hands with soap and water after handling them, never put fingers in mouths, and never eat a wild snail. Keep them for a few days at most and put them back where you found them.
A snailery
Comstock's directions: a glass jar "with a little soil and some moss or leaves at the bottom, and a shallow dish of water at one side. The moss and soil should be kept moist." Give fresh leaves or bits of fruit, and cover the top with cloth and a rubber band.
Keep the big idea in mind
Comstock's "leading thought" is the one idea the lesson is meant to lead to. Read it to yourself now, and save it to share at the end, after your child has looked and answered:
The snail carries his dwelling with him, and retires within it in time of danger. He can climb on any smooth surface.
One foot
Let a snail crawl onto the clear glass and look at it from underneath.
How does a snail walk? Describe its "foot." How can it move with only one foot? Describe how it climbs the side of the glass jar. How does it cling?
What sort of a track does a snail leave behind it? What is the use of this mucus?
Look for ripples moving along the underside of the foot.
Eyes and feelers
Where are the snail's eyes? Why is this arrangement convenient? If we touch one of the eyes what happens?
Touch an eye-stalk only very lightly, with the tip of a soft grass blade.
Look below the eyes for a pair of feelers. What happens to these if you touch them?
The shell
What is the use of its shell to a snail? What does the snail do if startled?
How many spiral turns are there in the full-grown shell? Are there as many in the shell of a young snail? Can you see the little ridges on the shell? Do you think that these show the way the shell grew?
Then read the leading thought aloud.
Nature notebook
Draw the snail from the side with its eyes on their long stalks and the short feelers below, and draw the shell from above with its spiral. Count and write the number of turns.
Afterwards
Listen closely when a snail eats a lettuce leaf: you may hear its rasping tongue. Comstock asks: "Describe the way it eats. Can you see the horny upper jaw?"