Lesson: Molluscs: Snails, Bivalves and Octopus

For: Grades 1-3 (can be adapted to higher grades quite easily)
Unit: Science

BY: Robynn Honeychurch and Avril Bourquin

Length of Lesson: Approximately 3 hours*
*Please note that this is an extensive lesson plan containing lots of information and ideas. You, as the teacher should take the time to read through the following pages and determine which activities will work best for you and your students.


Instructional Goal
To provide students with an introduction to the invertebrate phylum of, mollusca and to help them gain a basic understanding of molluscs in general.
In this lesson plan, three main classes will be discussed in general. Those classes are; the gastropods, bivalves and cephalopods. The main emphasis will be on the terrestrial (land snail) gastropods. Discussions will cover such things as anatomy of the snail, needs of the snail and procreation of the snail. Your students will also learn how and why molluscs are important to humans and the environment.

 

Performance Objective
Students will create a report, including drawings and notes based on their observations of the snail, and what they've learned about them during the lesson. Students will participate in a discussion about molluscs, their value to humans and the environment.


Rationale
Molluscs are an integral part of our environment. In studying this life form, students will observe the way these animals are a very important member of our world today. The mollusc's reliance upon the environment in which they live, and the way in which humans rely on them, exemplifies the interconnectedness of all the ecosystems of the earth.

 

Lesson Content

  1. Introduction to molluscs, using terrestrial snails as the focus. Students will
  2. Introduction to the main classes of molluscs: gastropods (ex.: snails), bivalves (ex.: oysters and clams), and cephalopods (ex.: octopuses).
    Students will:

 

Planning Ahead
The following steps should be taken well in advance of teaching this lesson:

  1. Print out a copy of this lesson plan for yourself to follow. Decide what printed materials will be used for your lesson and have the appropriate pages photocopied.

  2. Research your locality for available resources such as, museums with shell collections, local aquariums, local shell clubs and or shell collectors in your vicinity. Often you can find someone willing to come into your classroom to present and display their shell collection. Field trips may also be planned as part of your lesson plan.

  3. Teachers should also collect some shells to share with their students. Do this a few weeks before you first lesson. Check your local museums, ask friends, look for shell clubs in your area. Many people collect shells and may have some to lend you.


  4. Several weeks before your first Mollusc lesson, encourage your students to look for shells of all kinds. Perhaps their relatives or friends will have shells which they are willing to lend out. Place each student's contribution in their own labeled bag, so that shells can be returned to the rightful owner after the completion of the lesson.

    If you live by the seashore, or lakes, or rivers encourage students to bring in their own shells to class. Make sure these shells are clean (a mild bleach and water solution under adult supervision cleans up most shells) and not inhabited or filled with decaying matter. These shells should also be placed in bags and labelled with the students name. You may also prompt the student to place a paper with their find as to where the shell was found the date it was found and if it was alive or dead when collected. Have them write down as many details as they can in regards to their finds.

    *** Be sure to heed this, and share this with students: if shells are brought from far away, make sure there is nothing living in them! Clean out the shells before they leave their place of origin. The propagation of misplaced molluscs can cause serious environmental and ecological damage!

  5. If in your lesson plan you are going to include living nails in a terrarium or aquarium; be sure you have the appropriate food, water and other necessities such as a calcium source available for feeding the snails that you will collect and house.. Have your snai'ls terrarium or aquarium created BEFORE you collect or purchase your snails. (See the MATERIALS section below for instructions on creating your snails' home.

  6. If you plan to use garden snails for your students to observe, plan to collect them well before you want to use them in the classroom. Sudden changes in the weather can send an apparently plentiful supply into hiding so that none will be available. This is also good advise if using live freshwater snails.
    Often live terrarium or aquarium snails can be purchased at pet stores. See details of collecting and looking after snails at the bottom of the Materials and Aids section of this lesson plan.

  7. Before your first lesson, Print out "Sammy's Adventure" story, additional activity pages and any other handout information sheets you plan to use for your class. You may also wish to photocopy the colouring pages included at the end of this lesson plan. Photocopy as many copies of each as you will need. All materials found on this lesson plan are the property of Man and Mollusc and are uncopyrighted for educational use and can be freely used for all educational needs. The exceptioon is "Sammy's Adventure" This story is copyrighted but may be used freely for all classroom lessons. An illustrated "Sammy's Adventure" story book will be published within the next year (2002). To learn where and when this book will be available, check with the owner, Avril Bourquin: avril@rockies.net

  8. Optional: A few weeks before you teach this lesson, check through some of the sites listed on the Additional Resources section at the end of this lesson plan. There are extra more games, puzzles, pictures or information about molluscs that you may wish to use.

  9. A few days before your first class, search out books at your school or community library on molluscs to bring into your classroom and share with your students. Bring as many of your School Library books on molluscs to your class as possible. This way students will know what to look for in their own school library.

    Optional Ideas that take some pre-planning

  10. Escargot can usually be bought ahead of time at most grocery stores and can be brought in to class to show students an example of edible terrestrial snails. For class use; open a container of escargot, wash and place them in a clean container filled with rubbing alcohol. Replace alcohol, as needed, when it begins to go brown.

  11. Oysters, clams, scallops and mussels can usually be bought ahead of time at most grocery stores to be preserved for class as well.

  12. Living marine molluscs can also be purchased of found nearby if you live at the ocean and these may be kept in a saltwater aquarium and kept alive for the classroom. Use local beach water for these specimens unless you are used to maintaining a salt water aquarium. This water must be replaced regularily and an airation stone is a must. I would only encourage you to keep such living speimens for one day only unless you are proficient at salt water aquarium keeping.

  13. If you are a really ambitious and creative teacher you may even decide to cook up a seafood meal for his/her students as an introduction to this mollusc unit. Parents may also be of help in preparing a seafood or molluscan feast . Notes sent home with a student well in advance of this lesson may help you to locate volunteers.

  14. A field trip could be planned to search out molluscs; (snails oysters, and clam, etc.) and to observe them in their natural habitat. Seashore rock pool or tide pools, lake shores creeks, and rivers make an excellent field trip. Visit these areas well in advance of taking your students so that you know for sure where to locate snails. If going to a beach, be sure to know what the tide status will be for this day as well. Tide and rock pools may totally disappear if you have a ghigh tide. Also be sure to have adequate supervision for all students if undergoing such a fiels trip. Once agin, check wheter or not you have a local shell club which might be of help to you on such a trip.

  15. Museums or aquariums with a focus on sea life or molluscs can also make a good field-trip destination for this unit. Often if you speak to the curators of such facilities, special arrangements can be made to have a special display and onsite talk for your class. Give these people as much time as you can for arranging such a visit.

 

Materials and Aids

  1. Copy of the lesson plan
  2. Rubbing alcohol and jars with tight fitting lids for preserving any living tissues to be used for the classroom
  3. Bags and labeling pen for storing the students' shell contributions
  4. Collected shells (found by students or teacher or both)
  5. "Sammy's Adventure" story (enclosed at the end of this lesson for printing out)
  6. Colouring pictures (also enclosed at the end of this lesson plan)
  7. Printed handouts on molluscs for students (also enclosed at the end of this lesson plan)
  8. A large piece of coloured Bristol Board or poster paper for a final display
  9. Miscellaneous sheets of coloured paper
  10. Blank paper, pencils and erasers for drawing snails and recording facts
  11. Crayons and or pencil crayons for colouring pictures and drawing snails and shells
  12. Scissors for children's use
  13. Glue
  14. Terrarium or aquarium with snails, plus their food and water source. Keeping a living exhibit is discussed in the next section of this plan

 

Instructions on assembling a terrarium exhibit are as follows:

Active snails can be kept for classroom viewing in a terrarium made from an aquarium, a large, wide mouth jar turned on its side, or a fish bowl. The top should be securely covered with screen or part of a nylon stocking. Lids which have holes punched in them do not allow adequate ventilation and the sharp edges on the interior are a safety risk to both snails and students.

To collect terrestrial snails you will need a shovel,and a container (to put your snails in). Make sure your container is not airtight so that the snails can breathe by making tiny holes in the lid. Use a plastic container to avoid sharp edges. (You need a lid to cover your container because snails can crawl on any texture or surface.) to find the snails; choose a damp spot such as, under leaf litter or near a pond. Use your shovel to loosen the ground and you should find many snails just beneath the surface. Be sure to collect some of the soil or leaf litter for use in your terrarium.

Terrestrial snails may be collected around gardens and in trees in your own area. Be sure to locate these well in advance so you know where to find them for your classroom. Be sure to know what they eat and include it in your terrarium. Keep the terrarium clean and food and water supplies clean. Plan to release these snails back to their original home upon completion of the lesson. If they are a known pest, you might well have them properly destroyed and keep the shell for future use.

In your terrarium, water can be supplied in a shallow, plastic lid, in a deeper dish containing a water soaked sponge, or by generously sprinkling lettuce or other fresh, leafy food with water. Create a sample habitat by including damp soil, or sand, plants, and rocks.

Food can also be placed into a shallow plastic lid in the terrarium. Most terrestrial snails are vegetarians and eat many kinds of plant material. Cornmeal, oatmeal, and fresh green leaves are all appropriate foods. Chalk, a cuttlefish bone from pet store (NOTE: this is a mollusc) or eggshells should be placed into the terrarium to provide the calcium necessary for healthy shells.

Cleaning to remove moldy food, the build up of mucus, and droppings, should be done on a regular basis.

Overcrowding the snails should be avoided. In terrariums, too many snails in too small a space, or inadequate ventilation can cause the humidity to rise to unacceptable levels and the snails will die.

If time permits, (are you keeping the snail for a few weeks or more) , the lifecycle of the snail can be observed in the classroom. Adult snails can be recognized by a small lip that is added to the open end of their shell when growth is complete.
Most terrestrial snails are hermaphroditic (each snail had both male and female sex organs), any two snails can mate. Each fertilizes the eggs of the other. The eggs are usually laid in a hole that the snail digs in the damp soil or under bark or damp leaf litter The small, translucent white eggs about the size of small peas.

Snails which withdraw into their shells during class can usually be coaxed out by a brief dip in a shallow container of water.

Upon completion of your lesson, plan to return all snails to their original home. If they happen to be a known pest species, they may be disposed of appropriately and their shells cleaned and kept for future lessons. Soft parts may also be kept in formeldyhye or rubbing alcohol.

 

Instructions on assembling an aquarium exhibit are as follows:

For freshwater snails, search along the lake shores river or creeks. Be sure to look under wharfs, stones and on water plants. Use a fine meshed collecting net to retrieve snails. Be sure to collect a good supply of the water the snail is found in. This is the best way to make sure the snail remains healthy. Use only this water (you may add an aeration stone, and filter system to keep the snails healthy and happy. Rocks covered with mosses and algae found around the snail should also be added to the aquarium. This aquarium should also have a lid or stocking cover as pond snails sometime do crawl out of the water.

You may have a fully water-filled aquarium or just a pool of water around such things as rocks and old tree branches from the area where you found the snail. This allows the snail to crawl on and up out of the water. An aquarium lid or mesh top to prevent escapes is still a vital part of this setup.

Be sure to return all living snails to their place of origin or have them properly disposed of, if they by chance are a known pest species, at the completion of your lesson.

Sometimes salt water molluscs can be found at a pet stores or if you live by the ocean, they may also be collected on the seashore around rocks in the inter-tidal zone. Once again, be sure to collect a good supply of the water where they live for your aquarium. These molluscs should be returned back to the ocean ASAP as they will not survive long in a simple aquarium

If you are going to use an established salt water aquarium, I would strongly suggest that you understand the basics of maintaining such an aquarium. Another option would be to have a knowledge person placed in charge of your aquarium for you. Check at your local pet shops for such help.

 

Teaching Procedures

  1. Teacher should encourage students to share what knowledge they have about molluscs ahead of actually starting the lesson. Have students bring in shells and bag and label them as discussed above. This may be done any time before the beginning of the actual lesson plan.

  2. Teacher will read "Sammy's Adventure" to students, first instructing students to listen for the facts about snails that are hidden throughout the story.

  3. Teacher will ask students what they have learned about snails from this story.

  4. Students will be asked to carefully observe the snails in their habitat (the terrarium or aqaurium that the teacher has prepared.) Send students up in groups of four to study the habitat, while the other students remain in their seats and record, in note form on the same sheet where they will draw their snails, the facts they've learned about snails from the story they heard.

  5. If there's time and you're using terrestrial or pond snails, teacher can remove several snails from the habitat, and place them on mosit surface such as a big leaf from a head of lettuce. Encourage students to gently touch and pick up the snails so that they can closely observe their colours, shell pattern, body shape, size and texture. Remind students that they will be returning to their seats to do a detailed drawing of the snail they've observed. Have students also observe the contents of the habitat bottle, so that they can draw these in as well. If including this part of the lesson, YOU MUST have a place for the children to wash their hands well or at minimum have good disinfecting hand wipes available for use after handling the snails.

  6. Students will return to their seats and draw a snail in its habitat from memory, and write any additional facts or observations that they have learned from observing the snails. Encourage students to draw in as much details as they can: including the foot, tentacles, eyes, body and shell.

  7. Handout the snail diagram for students to study and label.

  8. Teacher will discuss the following facts with students:

  9. Teacher will encourage students to brainstorm:
    (If desired and have them prepared, hand out the pages on Introduction to Molluscs, Cephalopoda, Bivalves, and Gastropoda. These pages are from Man and Molluscs Beginner's Introduction to Molluscs found at: beginners_guide.html. The appropriate pages are also     printed at the end of this lesson plan.)

  10. What other sea creatures and land beasties can your students think of that might be molluscs? (be sure not to get mixed up with such things as starfish, sea biscuits and sand dollars etc, which are echinodrems)

  11. What do your students think these molluscs eat? ( you may want to talk about herbivores, carnivoires and paratsites if the age group lends to this. Filter feeding bivlaves to the hunting carnivoires such as fish-eating cone shells may be touched upon here as well.)

  12. What do molluscs need to live? (food, mositure, and a clean oxygen supply)

  13. Can students think of ways in which humans use molluscs? And their shells?

  14. What do your students think happens when the environment (ocean) where molluscs live becomes polluted: like with an oil spill or when sewage, industrial pollutants and garbage gets dumped into the earth's water systems?
    Ballast water from ocean liners is also another danger to ports. This is how such things as the zebra mussel got into the Great Lakes where they have created massive damage.
    Snails moved from one habitat to another may become bad pests and devastated crops and other vegetation.

  15. Discuss with your students what happens when the environment is disrupted due to lack of molluscs that were once present or when new introduced species overruns an area. Animals and man that feed upon this mollusc are losing a food supply. Where invasive molluscs go, food supplies that other rely on are in jeprodised and or crops may also be destroyed. How does all this affect man?

  16. Age level and time permitting, you may even want to touch upon some ways in which the medical world is presently studying molluscs. Such things as pain killers, cancer cures, skin adhesives for operations and materials for healing broken bones are being developed from molluscs.
    Medically, molluscs are also responsible for spreading many illnesses such as schistosomiasis. More information on Molluscs and Medicine can be found on the Man and Mollusc site at: /links_medicine.html

 

NOTE: Students can write down additional facts on the report they are creating about snails, as the discussion progresses. Teacher should prompt for this, writing key words and ideas on the board.

 

General Mollusc Information That Should Be Covered:

A more complete list of molluscan facts to cover is in the next section on" Snail Facts to Refer to When Discussing and Marking Projects":

 

Snail Facts to Refer to When Discussing and Marking Projects:

Molluscs (Mollusks; both spellings are correct)

 

Gastropods: Terrestrial or Garden Snail Facts :


Achitina fulica (Giant African Land Snail)

 

Gastropods: Aquatic (Pond or other Freshwater) SNAIL Facts:


Pomacea bridgesi (Golden apple snail)

 

Marine Gastropods Facts (these are the conchs (Strombidae), whelks (Buccinidae), limpets (Lotiidae), periwinkles (Littorinidae), cones (Conidae), volutes (Volutidae), and cowries (Cypraeidae) that we mostly know)


Cypraea moneta (Money cowrie)

Bivalve Facts:


(Giant Bittersweet Clam)

Cephalopod Facts


Giant Pacific Octopus

 

 

Closure

  1. Have students examine the shells that have been collected for this lesson plan. With the use of books or Internet resources (like the visual identification kit suggested in the Resources section at the end of this lesson plan) see if students can identify their finds. Have each student choose a shell to take back to his or her desk to draw. Encourage them to use colour. Students can cut out their drawings once they are completed. Students can arrange cut-out shell drawings on the large poster board and glue them down. Shells can be labeled and poster displayed in class. Sample title for this is "Molluscs We Have Found."

  2. Provide students with colouring sheets to colour in class, or to take home, if there's not time in class. Discuss what colours the molluscs in the pictures would likely be (camouflage). Continue on with any additional activities that you wish to add to the unit.

  3. Collect snail drawings and fact notes.

  4. If time and space permits, keep the snails in their terrarium in the classroom for several weeks. Have the students help in feeding them and keeping their home clean. Have them observe the lifecycles of the snails, draw more pictures, and record their observations in the form of a small report about their lifecycle.

  5. OPTIONAL: Man and Mollusc has a children's art and story page set up online where children may have their works of art, stories, limericks, poems etc. placed. These can be viewed fro the Children's Zone at: /kid_zone.html. To have items placed on these pages, contact Avril Bourquin and arrange for this

 

Evaluation Procedures

  1. Evaluate what the students have learned (gleaned whether or not students are comprehending and absorbing the information presented). This can be done by:
  2. Mark the snail and shell drawings and listed facts based on: what student has been able to observe, learn, infer and record about snails, and molluscs in general.
  3. What students have learned and inferred regarding the class discussions and story should also be taken into account and related discussion and story.
  4. Consider the contribution each student made to the brainstorm/discussion on molluscs, as well.
  5. Consider the ability of each student, the accuracy of their observations, and the time they each spent on these class projects.
  6. Optional:If you have chosen to keep the snails in the classroom and have asked the students to do a follow-up report on the lifecycle of the snails, make sure to collect these and mark them based on the accuracy of their observations and the time they've put into their project.

 

References

 

  1. Man and Mollusc web site: www.manandmollusc.net by Avril Bourquin
  2. "Sammy 's Adventure" story by Robynn Honeychurch, Anna Palumbo and Avril Bourquin
  3. "Eye to Eye with Garden Snails" Lesson plan by Kathy Lu

 

Additional Resources

  1. Web pages: Many good educational pages may be accessed through Man and Molluscs Teacher's Zone at:
  2. A Visual Identification Kit put together by Avril Bourquin to accompany this lesson plan is located at: www.manandmollusc.net/
  3. These websites also have games, pictures and other materials you might use:

 

Lesson Plan Inclusions:

  1. Sammy's Adventure (story) This story is copyrighted but may be freely used for the classroom without the owners permission. This story will be available in late 2002 in an illustrated book. You may wish to conatct Avril Bourquin (Email: manandmollusc@telus.net) to learn when, where and how this book can be purchased

  2. Snail Diagrams (labeled and unlabelled)

  3. Colouring Pages: Choose those pages you wish to use

    4.  

  4. Suggested Handouts for Students: A Beginner's Introduction to Molluscs: Bivalves, Cephalopoda and Gastropoda or compete article in printer friendly version: beginners_intro_printable.html
  5. Visual Shell collection identification aid

  6. OPTIONAL: Additional Activity Idea: Make an Origami Snail: /origami_snail.html

  7. OPTIONAL: Amazing Molluscan Facts: from Man and Mollusc site: /amazing_facts.html

  8. OPTIONAL: Man and Mollusc: Uses of Shell-Bearing Molluscs Past, Present & Future:
    Simplified Version: by Avril Bourquin: man_and_molluscs_a.html or printer friendly version: advanced_uses-print.html

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