Meet the Mollusks

 

Revised by Chris Lundberg, Program Coordinator

Mathematics & Science Center

 

Developed with funding from the Mathematics & Science Center


Major Understanding

The second largest phylum of the animal kingdom consists of soft bodied animals called mollusks.  Phylum Mollusca is composed of seven classes, chief of which are the classes Bivalvia, Cephalopoda, and Gastropoda.  This lesson focuses on how this major group of animals adapts to land, fresh, and saltwater ecosystems in a variety of unique ways to meet their needs as living organisms.

 

Grade/Subject

Science 6-12; Biology, Life Science, Environmental Science.

 

Objectives

Investigate the seven classes of mollusks and identify the unique characteristics of the three main classes.

 

 

Describe how mollusks are adapted to meet life needs.

 

 

Use the following terms correctly:  adaptation, taxonomy, Mollusca, univalve, bivalve, gastropod, cephalopod, mantle, radula, proboscis, hermaphrodite, scavenger.

 

 

Use a taxonomic key to identify and classify a group of different kinds of mollusks.

 

 

Examine and report on the behavior and anatomy of a living representative mollusk specimen, the eastern Mud Snail (Ilynassa obsoleta).

 

Time

Introduction/Anticipatory Set

10 min

Explanation:  PowerPoint Slide Presentation

20 min

Lab Activity:  Mud Snail

20 min

Practice Activity:  Review of Student Handout:  Meet the Mollusks

5 min

Classification Activity: Shell Classification Key

   15 min

 

Closure:  Review of Mollusk Characteristics

 

10 min

Materials

 

Credit: U.S. Geological Survey

For Students

Student Handout: Meet the Mollusks

Petri dish

Magnifying glasses

Paper towels

Set of 10 bags of shells

Shell Classification Key

 

For the Teacher

Minnow bucket/cooler with aerator or classroom

Saltwater aquarium

Wash bottle

Living Mud Snails (Ilynassa obsoleta)

Preserved specimens of Octopus, squid, snails, slugs, scallops, oysters,

    clams

Salt water (Instant Ocean or Crystal Sea)

PowerPoint Presentation:  Meet the Mollusks

Computer and projector or large monitor

State and National Correlations

Virginia Standards of Learning:  Life Science (LS.4, LS.5, LS.10, LS.11); Biology (BIO.5, BIO.7, BIO.8, BIO.9); Biology II Courses.

 

National Science Education Standards: Content Standard A (develop descriptions, explanations, predictions, and models using evidence, think critically and logically to make the relationships between evidence and explanations); Content Standard C (structure and function in living systems, regulation and behavior, populations and ecosystems, diversity and adaptations of organisms).

 

Instructional Strategies

 

Photo courtesy A.C. Lundberg

1.  Introduction/Anticipatory Set

Ask students to define a mollusk.  Pass around samples of various shells and ask students what type of animal used to inhabit the shells.  Pass out Student Handout: Meet the Mollusks.

 

2.  Explanation:  PowerPoint Slide Presentation

Follow directions included in Teaching Tips – Teaching Notes for PowerPoint -- to present lesson explanation.  Instruct students to record their observations on the chart on the handout.  During instruction, pass around samples of squid, chambered nautilus, octopus, whelk, oyster, etc.

 

3.  Lab Activity:  Mud Snail

Organize students into groups of two or three.  Pass out mud snails and magnifiers.  Instruct students to look for the following structures:  foot, proboscis, siphon tube, tentacles, eyes, operculum, radula.  Instruct students to make observations of the mud snail’s behavior. Pass out mud snails, magnifiers, and worksheets.  Note:  a little sprinkle of fish food will help make the snails more active!  Instruct students to label their diagram and to make notes of the behavior of the mud snail.

 

4.  Classification Activity:  Shell Classification Key

Pass out the taxonomic key guides and the shell packets.  Instruct students how to complete the activity by modeling the classification for the first shell, if necessary.  Each student group (students work in pairs or triads) should have 1 bag with 9 mollusk shells, 1 mollusk shell key (with Mollusk Shell Dictionary on the back).

Instructions to use the dichotomous shell key:

  1. Choose one shell from the bag.  Your group should work with only one shell at a time.
  2. Examine the shell.  Look at the Mollusk Shell Key.  Always start at the beginning (Letter A).  Read the pair of descriptions.  Decide which of the two descriptions fits the shell the best.  Then go to the letter that follows that description.
  3. If you don’t understand the meaning of a word on the key, look up the word’s definition on the Mollusk Shell Dictionary.
  4. Continue to follow the key, choosing the best description from each pair.  When you come to a shell name, write this name on the answer sheet in the blank that matches your shell number.
  5. When you have identified all nine of your shells, re-check your answers by classifying your shells again with the key.

 

 

5.  Practice Activity:  Review of Student Handout

Review correct answers for the mud snail lab activity and the classification activity.  Expand and elaborate on student responses and questions.  Click here for the mollusk shell answer key.

 

Closure

Review of Mollusk Characteristics
Review with students the kingdom phylum, and characteristics section on their handout.  Ask students to define a mollusk and name the 3 major groups of mollusks.  Ask students to name several different types of mollusks and identify at least 3 special adaptations of mollusks they observed in the lesson.

 

Extensions

 

Credit: U.S. Geological Survey

1.      Have students research and report to the class on unique mollusks and how these organisms deal with satisfying the requirements for a living organism.  Students can also research and report on how scientists conduct fisheries management efforts to conserve endangered species in the Chesapeake Bay such as the Eastern oyster (Crassostrea virginica)

 

2.      Check our out special “Mollusk Cam” to observe mollusk behavior under the microscope and a close-up look at its radula in action!

 

3.      Set up your own ecosystem aquarium to learn about mud snails and other aquatic organisms.  See Carolina Tips, Summer 2002, at the Carolina Biological web site, www.carolina.com, for information.

 

4.      Have students design and conduct an experiment to determine how mud snails respond to environmental stimuli.   Responses such as phototaxis, geotaxis, and chemotaxis can be investigated.

 

5.      Many species of squid contain bioluminescent bacteria in their skin.  Have students research the topic of bioluminescence and its relationship to the life of aquatic organisms.

 

Assessment

The following items are provided to asses student understanding:

Paper-pencil Test: Meet the Mollusks.

Product: Meet the Mollusks

Rubric:  Meet the Mollusks

 

The following table shows how the assessment items are related to specific objectives.

 

 

Objective

Paper-Pencil Test

Product/
Performance

Investigate the seven classes of mollusks and identify the unique characteristics of the three main classes.

2, 8, 11, 14, 15

 

Describe how mollusks are adapted to meet life needs.

5, 7, 9, 12, 13

 

Use the following terms correctly:  adaptation, taxonomy, Mollusca, univalve, bivalve, gastropod, cephalopod, mantle, radula, hermaphrodite, scavenger.

3, 6, 10

 

Use a taxonomic key to identify and classify a group of different kinds of mollusks.

1, 4

 

Examine and report on the behavior and anatomy of a living representative mollusk specimen, the Mud Snail (Ilynassa obsoleta).

 

 

Major Understanding:  The second largest phylum of the animal kingdom consists of soft bodied animals called “mollusks.”  This Phylum, Mollusca, is composed of seven classes, chief of which are the classes Bivalvia, Cephalopoda, and Gastropoda. This major group of animals adapts to land, fresh, and saltwater ecosystems in a variety of unique ways to meet their needs as living organisms.

 

Product & Rubric

 

 

Teaching Tips

 

Check out these teaching tips for background information, an expanded lesson script, including slide presentation notes, and sources to obtain living and prepared specimens for the lesson.

Answer Key for Paper-Pencil Test:  Meet the Mollusks

 

Answer Key for Mollusk Shell Key

 

Background Information

 

Teaching Notes for PowerPoint Presentation

 

Sources of Lesson Materials

 

References

About Octopi

This is provided by the MarineLab research organization in Sarasota, Florida.  A great site to begin exploring the anatomy and behavior of the octopus.

http://www.marinelab.sarasota.fl.us/OCTOPI.HTM

 

Animal Diversity Web

Site of the Animal Diversity Web University of Michigan Museum of Zoology.  Presents good basic information on mollusks, bivalves.

http://animaldiversity.ummz.umich.edu/mollusca/bivalvia.html

 

Cephbase

CephBase is an html relational database driven interactive page providing life history, distribution, catch and taxonomic data on all living species of cephalopods (octopus, squid, cuttlefish and nautilus).  Lots of great photos and videos.

http://www.cephbase.utmb.edu/

 

In Search of Giant Squid

This is an on-line exhibit provided by the Smithsonian Museum of Natural History.  Learn the inside story on squids, from myth to reality, with this interactive site.

http://seawifs.gsfc.nasa.gov/squid.html

 

MathInScience.info

Visit our educational resource site to acquire web-based lessons and resources for students and teachers.

http://mathinscience.info

 

The Mathematics & Science CenterWhere it all adds up!  Web site of the Mathematics & Science Center with a variety of information on programs and opportunities for students.

http://www.mathscience.info

 

Opistobranch Nudibranch Seaslug

This site provides an e-mail listserver, bibliography, and search engine for taxonomic files and links to over 2,400 color opisthobranch photos from around the world.

http://www.seaslug.com

 

Unio Gallery of Freshwater Mussels

This site provides a gallery of wonderful photographs from Southwest Missouri State University intended to encourage interest in the freshwater pearly mussels, in the hope that educators will make use of the images to promote conservation of these endangered mollusks.  http://courses.smsu.edu/mcb095f/gallery/