Lesson 2

# How is the metabolic rate of clams effected by a change in temperature?

Objectives:
Students will be able to:
• Determine the optimal temperature at which a clam's metabolic rate functions

• efficiently.
• Evaluate the changes, if any, which a clam undergoes at various temperatures.
Note: Safety goggles and aprons should be worn at all times during this lab activity.

Materials:
Salt water
3 thermometers per group
3 500 milliliter beakers
Large pan to use as an ice bath
Petri dishes
Red or blue food coloring
3 clams per group
Hot plate

Procedure:
Working in Groups of Three:
1. Fill three 500 milliliter beakers approximately half full with salt water. Label the beakers in the following manner:

• Beaker 1 - Room temperature
• Beaker 2 - Ice bath
• Beaker 3 - Hot plate
2. Place a thermometer and a clam in each of the three beakers.
3. Place beaker 1 on the lab table in an area where it will not be disturbed.
4. Make an ice bath using the large pan or container. Place beaker 2 in the large pan or container and place ice around the beaker. Add water so that the beaker is half way submerged in the ice bath.
5. Place beaker 3 on low heat on a hot plate.

Note: Do not allow the water to reach the point of boiling.

6. Each member of the group should take a thermometer reading from beakers 1, 2 and 3,
after the temperature stabilizes. (Approximately 10 minutes)
7. Record the temperature on the data table.
8. Hypothesize as to which temperature will allow the most efficient functioning of the clam's metabolic rate. The hypothesis should contain a statement about temperature.

Note: Wash hands thoroughly with soap and water after handling the clams.

Hypothesis:

Each member of the group should do the following simultaneously.
9. Place a drop of red or blue food coloring approximately 1 centimeter away from the pointed end of the clam. Note the time on the data table. This is Time 1.
10. Watch the clam and look for the colored water to be expelled or forced out of the clam. Record the time when the clam expels the colored water. This is Time 2.
11. To determine the differences in the time, subtract Time 1 from Time 2 and record the difference in the last column of the data table.

Data Table:

After the observations are complete, answer the following questions

Conclusions:
1. Does the data collected support your hypothesis? Why or why not?

2. Based on your observations, what is the optimal temperature for the metabolic rate of  a

3. Based on your observations, how does a temperature increase or decrease change the
metabolic rate of aquatic organisms?

4. How do you think this would this effect the aquatic ecosystem as a whole? (Consider
other organisms such as macroinvertebrates and fish)

5. Research the effects of an increase or decrease in metabolic rates in aquatic organisms.
Based on your research, write a short paragraph explaining how this will detrimentally
effect the ecosystem as a whole.

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