What s Beneath the Shell? Subject Areas: Science, Math Setting: Classroom Duration: One class period Skills: observation, drawing, critical thinking, motor skills, identifying, calculating Vocabulary: foot, siphon, meat, gills, hinge, ligament, stomach, cilia, crystalline Style, mantle, shell Correlation to Core Curriculum Standards: Science: 5.1 (A,B), 5.3 (A,C,D), 5.10 (A,B); Math: 4.1 (A,D), 4.5 (A,C) Life Skills: 9.2 (A) Objectives: 1. Students will learn about the internal parts of a clam 2. Students will understand how clam anatomy differs from their own 3. Students will understand the impact of clams on bay ecology Materials: paper clam models for students, scissors, pencil and journal, live clam or oyster for observation, hand lens, clam knife or paring knife, optional: algal culture (diatoms or chlorella) to feed clams (you may order this from a science education catalog) Background: Procedure: Using a small fishbowl or large container, have a live clam and oyster on display in the room. Explain that in simple terms, a clam is just a pump and filter. It takes water in through its siphon, filters plankton and nutrients out, and 20
then returns the water. Carefully open a live clam and pass it around the class. Ask students to notice the large muscle that takes up most of the shell, the foot. Add a drop of food coloring to the open clam or oyster shell, and have students watch the color as it moves around the body of the clam. (This would work very well if equipped with a stereo microscope hooked up to a television.) Procedure: Activity - Short Term/Younger Grades Copy cut out clam models for class. Have students cut out the paper clam model, and color in the various structures. When the students staple the clam at the hinges they will have a 3D model of a hard clam, from the outside shell inward. Procedure: Activity - In-Depth/Older Grades Explain that different shellfish filter the water at different rates. A two-inch oyster can filter up to 50 gallons of water a day, while a similarly sized hard clam will only filter 10-12 gallons per day. Tell them that ReClam the Bay has grown 1.8 million hard clams, and 100,000 oysters. Using this information, have students estimate how many gallons of the bay these shellfish would filter every day if they all survive. What if only 50% of them survive? Share with the class that the Barnegat Bay holds approximately 60 billion gallons of water. How many days would it take 1.8 million clams and 100,000 oysters to filter the whole bay? A worksheet is provided to answer these questions. Extension: Taking it further Have students dissect a hard clam. Teach them to carefully open the shell with a clam knife. **Instructions** Using the clam model as a guide, have students identify major structures inside the clam. They should draw what they see in their journals, and label all of the structures. Assessment: Class participation 21
Completion of clam model or worksheet Filtering Calculations worksheet Journal with dissection notes and drawings Also see: Clam Anatomy from Beneath the Shell, NJDEP. 22
Filter Worksheet A two-inch oyster will filter up to 50 gallons of water per day. A similarly sized clam will only filter 10-12 gallons of water per day. Using this information, solve the following problems: 1. Reclam the Bay has grown 1.8 million clams and 100,000 oysters. When they reach a size of about two inches, about how much water will they filter per day, total? Clams Oysters Total 2. If only 50% of the clams survive, how much water will they filter daily? Clams Oysters Total 3. There are approximately 60,000,000,000 gallons of water in Barnegat Bay. How many days would it take for these clams and oysters to filter the whole bay? How many years? Days Years 23
Filter Worksheet Answers A two-inch oyster will filter up to 50 gallons of water per day. A similarly sized clam may only filter 10-12 gallons of water per day. Using this information, solve the following problems: 1. Reclam the Bay has grown 1.8 million clams and 100,000 oysters. When they reach a size of about two inches, how much water will they filter per day, total? 1,800,000 x 11 (average)= 19,800,000 gallons 100,000 x 50= 5,000,000 gallons 19,800,000 + 5,000,000 = 24,800,000 gallons 3. If only 50% of the clams survive, how much water will they filter daily? 24,800,000/ 2= 12,400,000 gallons 3. There are approximately 60,000,000,000 gallons of water in Barnegat Bay. About how many days would it take for these surviving clams and oysters to filter the whole bay? About How many years? 60,000,000,000/12,400,000 = 4839 days 4839/365=13 years 24