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The Great Whales

Instructional Objectives
Background Information
Activity
Procedures
Evaluation
Elementary and Secondary Extensions


Topic: Whale Blubber

Instructional Objectives:

Students will:

  1. Learn about the whale's layer of insulating fat, known as blubber.
  2. Conduct a simple experiment to test the effectiveness of fat as an insulator.
  3. Discuss how humans use insulating materials to protect themselves from cold exposure.

Background Information:

Whales are warm-blooded mammals that can survive in water temperatures as frigid as the low-40s F. How do they manage to stay warm, even in the ice-cold waters of the North Pole and Antarctica? By wearing a thick layer of fat-called blubber-just beneath the skin.

How does the whale acquire this fat layer? Being mammals, whales suckle their young. A baby gray whale, for example, may drink up to 30 gallons of its mother's milk-which has the consistency of soft margarine-every day! An adult gray whale, on the other hand, may eat tons of crustaceans during a given feeding period. All of this intake is necessary to not only provide the whale with the energy it needs to swim great distances and dive to incredible depths, but to help maintain an essential layer of fatty insulation.

Activity: Make a "Blubber Glove"

Time Needed For Activity: One 45-minute period

Target Grade Level: Middle School

Materials:

  • One box of large Ziplock freezer storage bags
  • One box of smaller Ziplock sandwich bags
  • Depending on class size, multiple cans of shortening
  • Plastic buckets of ice water

Procedures:

  1. Let the students work in small groups, with each student taking one large and one small Ziplock. Give each group one bucket of ice water and a can of shortening.
  2. Have the students fill each of their large Ziplock bags with about six inches of shortening.
  3. Instruct students to take turns placing their small Ziplock bags on one of their hands, and then placing the covered hands in the ice water. Have students time one another to see how long they can withstand the cold. Instruct students to keep precise records of the results.
  4. Next, have students switch hands, placing their warm hands in the small bags and then their bagged hands inside the larger bags containing the shortening. Run the ice-water dip test again, this time with the insulated hands. Again, keep exact time records of the results.

Evaluation:

Collect results of the two tests (uninsulated and insulated) and compare. Students should draw conclusions regarding the effectiveness of fat (shortening) as an insulator. Have them consider how effective a thick layer of blubber must be in order to keep a whale warm while submerged in cold water throughout its life.

Discuss the applications of insulation for cold protection in humans. Point out that long-distance swimmers, such as those who cross the English Channel, typically coat their bodies in shortening or other fatty compounds. Consider the fact that Native peoples inhabiting arctic regions rely in their diets upon blubber and other fatty foods they harvest from marine mammals to help build and maintain a fat layer of their own. Discuss the effectiveness of a diver's wetsuit in providing the same sort of thermal protection for a submerged human. (Remember that a wetsuit is a snugly fitting suit of spongy rubber called neoprene that traps a layer of water between itself and the diver's skin. As the diver's body temperature raises the temperature level of the water, the water retains this heat and maintains the diver's body temperature at a comfortable level. [If available, try neoprene gloves in the above experiment.])


Extension for Elementary:

Try a whale on for size. Adult gray whales may reach 45 feet in length. Newborns are about 15 feet long. To help visualize their size, have students cut pieces of string to match their own heights. Then measure and cut a 45-foot length and a 15-foot length. By comparing lengths, determine how much larger than the students an adult or baby gray whale is.

The blue whale grows to 100 feet. For an idea of this length, have the students pace off 100 feet on the playground or other outdoor area.

Extension for Secondary:

Evaluate the physics of a whale's deep dive. Students will need to chart depth and hydrostatic pressure accordingly: Begin with the fact that atmospheric pressure at sea level is approximately 15 pounds per square inch (psi). Factor in an additional 15 psi for every 33 feet of depth (one atmosphere) in the ocean. Gray whales are believed to dive as deep as 1,000 feet. How many atmospheres is this equal to? How many psi? Have students consider the effects of this tremendous pressure on the whale. What is likely to happen to the whale's lungs, for instance, as it dives? Have students consider the effects of submersion on their own bodies-lung constriction and sinus compression-when they dive to the bottom of a swimming pool.

Chart results for the deepest-diving species covered in the program: sperm whales (3,000-foot dives). Chart results for the deepest dive ever made by humans, aboard the Navy research submersible Trieste, to a depth of 35,810 feet.


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