The spotted leopard slug. |
The air-breathing molluscs (Pulvionates) in which the shell is internal or entirely absent are popularly called slugs ( Limacidce ). On the front part of the back, near the head, these animals have a fleshy plate, the mantle, near the right edge of which is the opening or pore by which they breathe. Slugs closely resemble snails in structure ; indeed, all the six families into which slugs may be divided, seem to have been derived separately from shell-bearing ancestors. They love dark and damp places, and crowd together in cellars and outhouses and under planks and stones. As they hide themselves during the day and only issue forth at night the damage done by them is often attributed to other creatures, though the presence of slugs may be recognized by streaks of slime in the neighborhood. All the air-breathing molluscs can secrete mucus from their body, and in slugs this power is highly developed. When the animal is irritated the secretion of mucus is greatly increased, the secretion being partly defensive. They use the secretion in another way, for these animals will lower themselves from a tree or shrub by means of threads of mucus. Like snails, slugs often lift their heads and move their tentacles in search of objects around them. When they are frightened they draw their heads under their mantles and contract their foot. They lay their eggs, which look like small oval bags of jelly, in moist places. The eggs are from twenty to forty days in hatching, and the young slug attains its full size in a year.
Required for Observation: A live slug; a cabbage leaf; and a live snail. A picture of the slug, and a sketch of its teeth. a rasp
Method of Student Observation:
- Compare the body of the slug with that of the garden snail.
- Show the sticky nature of the slime, and point out that the slug will sometimes let itself down from a tree by a thread formed of its slime.
- Compare with the head of a snail. Explain that the horns are pulled inside out as they are retracted ; and imitate the movement by pulling the finger of a glove inside out by means of a string attached to the tip.
- Exhibit a diagram of the teeth.
- The children should watch the slug as it crawls, and observe the slimy track made by it. They should also be allowed to see the wave-like contraction of the under surface as the slug crawls on a piece of window-glass.
- Note that the slug is an air-breathing animal, and that it cannot live in water. Point out the pulmonary aperture on the right side.
- Show a rasp, and compare the action of the slug's teeth with that of the rasp.
- The children should be encouraged to seek the slug in its haunts, and observe its habits in the garden or during their rambles.
- Slugs' eggs should be procured if possible. They may be found under stones and other objects.
How To Grade Study Notes For Student Journals: Every student will need a journal to write in weekly for this online nature study series. Teacher will assign the weekly content in advance.
- Make sure the facts are: written in complete sentences, the first word of each sentence capitalized, and a period should be included at the end of each sentence.
- Spell check your vocabulary and write the words correctly.
- Dress up your journal entries with student clip art, drawings of your own in color or in black and white.
- Student may also include photographs of their own taking for extra credit.
Look for the following facts about slugs inside of student journals. Assign a point value to the quality of the content.
- General form - Body elongated and tapering before and behind. Convex above and flat beneath.
- Skin - Soft and slimy. In some species much wrinkled. Color whitish, yellowish, brown, or black, according to the species.
- Head - Provided with four retractile horns - -two longer and two shorter. Horns used as feelers, and the eyes are situated at the tip of the longer pair.
- Mouth on the under side of the head, and provided with numerous small teeth in parallel rows.
- Crawling - The slug crawls on its belly, moving itself along by a wave-like contraction of the muscles of its under surface. As it crawls it leaves behind it a streak of slime, which soon hardens on exposure to air.
- Breathing - The slug breathes by means of a lung, the air passing through an opening on the right side of the body.
- Feeding - It feeds on various vegetable substances, biting off small pieces with its teeth.
- The Slug at rest. The slug does not like the light and heat of the sun. It hides under cover during the day, and crawls about and feeds at night. It goes to sleep all winter, taking no food.
- Young - The young of the slug are produced from eggs. They do not undergo changes, like insects, but are, from the first, of the same form as their parents.
Video at Youtube for Students to Watch:The finished slug craft
photographed outdoors
- Solar-powered slugs by SciShow Kids
- Banana Slugs: secret of the slime by Deep Look
- Common Leopard Slugs Are Cool! by Discover Downeast
The Life Cycle of The Slug: Students will need writing and drawing tools, two white paper plates, scissors, white school glue and one brass-plated fastener. The teacher should supply the two paper plates and fastener per student. Draw the different stages of a slugs' life on the first paper plate dividing these into separate pie shaped grid. Color the second paper plate with leaves and twigs; the kinds of natural stuff found on a forest floor. Cut away one small pie shaped window so that the life stages may be viewed through the top paper plate after it has been joined to the first using a fastener at the center of both.
Craft a Slug From An Egg Carton: You will need the following supplies: masking tape, a 2 chenille stems. recycled cardboard egg carton, white school glue, tissue paper, acrylic paints, and Mod Podge
Left, the cardboard egg carton cut apart and chenille stem threaded through units. |
See the paper mache slug prior to painting after it has been covered with a layer of glue and tissue. |
The slug as seen from the top, side and bottom after painting it. |
I painted my version of a slug using multiple tan and brown colors because it is to represent a spotted leopard slug. However, students may choose to paint a banana slug yellow or some other kind of slug in it's own color variations. Once the painted surfaces are dry, cover the entire slug in stages with Mod Podge to seal it properly.
Free Student Clip Art: Clip art may be printed from a home computer, a classroom computer or from a computer at a library and/or a local printing service provider. This may be done from multiple locations as needed because our education blog is online and available to the general public.
Illustrated in the clip art above are the anatomical features of all slugs. |
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