Why Whales Don'tHave Legs
Background:
Warm-blooded animals must maintain body temperatures within a narrow
temperature range. If the animal's body temperature differs from that of its surroundings,
heat will be exchanged with the environment. We think of built in mechanisms such as
sweating, panting and shivering as ways that animals maintain their body temperatures, but
are there other more basic factors to consider? Are there temperature advantages to
whales not having legs because they live in cold, ocean water?
Problem:
Why don't whales have legs?
Hypothesis:
_
Materials: 2 gloves, string, large battery jar, ice, hot water, graduated cylinder, Lab Pro,
power supply, cable and two Temperature Probes.
Procedure:
1. Open up hard drive, open applications, open Logger Pro 3 folder, open
experiments, choose probes and sensors, choose temperature probes, and then
stainless steel temp probe. cmbl
2. Connect Logger Pro to the computer and two stainless steel probes to Logger
Pro, Ch 1 and Ch 2. Click on logger Pro icon in upper left hand corner for two
probes. Select CH 2; choose sensor, temperature, stainless steel temperature, and
then close. Use probe #1 to put into glove and collect data. Probe #2 will be used
to prepare the various temperatures of water. Choose experiment, data collection,
and collection setup. Default is 180 seconds (3 min.) and sampling is every second
(You may choose to collect more data for a longer time period). Choose done.
3. Take one glove and tie off the fingers so that no water can go into them (whale
no legs). The other glove will be used as is (whale with legs).
4. Add 300 ml of 37°C water (whale body temp.) and the end of the temperature
probe into the glove with fingers. Keep the probe in the middle of the glove (do not
touch glove). Completely submerge and hold in 22°C water (Hawaii), click Collect.
5. Logger Pro will record data and graph simultaneously for three minutes. When
completed go to experiment, store latest run, then go to data, data set options and
name the rUr] (22° with legs). Go'to data, select new data set, data is now ready to
be collected again.
6. Repeat steps four and five with the glove, no fingers. Recheck water temperature
in battery jar for 22°C. Modify if necessary. Collect data, when through collecting go
to data, data set options, name run (22° C no legs) Double click on graph, type in
appropriate title for graph, select point protectors, select legend. Select, file save as
choose documents, name file (Whales in Hawaii 22°C and your names). Choose
File, select print graph, you need one graph per group.
7. Repeat the steps above with rc water (Alaska). Name (Whales in Alaska rc
and your names). The lab will be repeated with the two·different gloves but using r
Cwater.
8. Retrieve data from your files and record beginning temp. °c and ending temp. °c
in table provided.
9. Answer analysis questions independently.
Data Table
Inside (22·C)
Glove
(37°C)
Maul
°c
·C
No
Fingers
Fingers
Temp
Differ ___
Final
Temp
Temp Differ ___
·C
oC
·C
Analysis:
1. Which of the two whales had the fastest rate of cooling? (Temperature
minutes)
change in three
2. How would you explain the effect of surface area on cooling?
3. Refer to the background section of the lab. Would having legs be favorable for whales?
4. What are advantages for whales not to have legs? Be specific.
5. How might this slight advantage have effected whale evolution?
6. Predict how adding a third glove with fingers and a temperature
temperature in air might come out.
probe to cool at room
7. Predict how altering the outside of the gloves with different insulating materials (solid
shortening, leather etc.) might affect the results.
4/3/08