Earth Systems

Standard IV, objective 2

Title: Adaptations to Life in Cold Water

Description: Students will investigate animal adaptations to a cold environment, specifically how they keep warm.

Materials: For demonstrations: 2 pieces of card stock, 2 empty cans, a large clear bucket, water, two toilet paper rolls. For student activity: For each student group- four freezer size ziplock bags, 1 3 lb. container of solid vegetable shortening, masking tape, a plastic container of cold water with ice cubes, stopwatch, weights and student sheets.

Time Needed: Fifty minutes

Procedures:

1. Hook: Discuss how quickly our bodies are chilled in the cold. Brainstorm ways in which seals, penguins, and other animals are well-adapted to cold water and icy environments (blubber, air in feathers, oil on fur, low surface area to volume ratio). Then complete the following demonstrations and discuss with students what they represent:

A. Flying birds need large wingspans to hold themselves up in the air, but small wingswork best for birds swimming through water. Demonstrate this with two pieces of flexible cardstock. Try to push one, flat, through a pan of water. It’s hard. Fold another piece fie or six times and try pushing that through the water. The smaller, stiffer card, like a penguin’s wing, works better.

B. Most birds have hollow bones to make their bodies light enough to become air-borne. But the penguins’ heavy, solid bones help them float lower in the water. With the help of two student volunteers, demonstrate the difference between hollow bones and solid bones using two toilet paper rolls, one empty, the other stuffed with tissue paper.

C. Float an empty can in a clear bucket of water open end up. It floats high in the water like flying aquatic birds (ducks, for example). Add sand to another can until it sinks slightly. Now push down on both cans. The sand-filled can is easier to push down. In this way, it’s easier for penguins to dive deeper into the water.

2. Hand out student sheets. Read through the introduction and procedures with them. You may wish to put a time limit on how long students should hold their hand with shortening in the water, otherwise they could stay there all day.

3. Give students time to complete the lab. Give them time to clean up. The shortening can be reused for each class.

4. Have them complete the analysis and conclusion.

Alternate Activity Option: Repeat the experiment with thermometers in place of the student hands. Record the temperatures over several minutes and graph the temperature vs. time results.

Scoring Guide:

  1. Students participate in hook discussions and lab………………………………………… 4
  2. Students complete data tables……………………………………………………………. 4
  3. Students complete analysis and conclusion……………………………………………… 4

Answers to questions:

  1. The control in the experiment is the hand without the shortening on it.
  2. The hand with shortening on it.
  3. blubber or fat
  4. The “glove” with shortening in it. Fat is less dense and so it floats easily.
  5. The ability to float; buoyancy.

Student Sheet

Name______Period______

Title: Adaptations to Life in Cold Water

Introduction:

Seals are mammals, just like you or your pet dog or cat. They are “warm blooded” and must be able to protect themselves against the cold water in the Polar Regions. The water in the Antarctic and Arctic is about 1.8 degrees below freezing and you would only survive 1-2 minutes in that temperature without protection. But, seals do very well in these conditions. How do they do that? Today you will be conducting an experiment to help you find out.

Procedures:

  1. Bring the following materials to your table: 4 plastic bags, 1 can of shortening, one plastic container with cold water and ice, a set of weights, masking tape, and a stopwatch.
  2. Cover one hand with a plastic bag.
  3. Put a generous amount of solid shortening into another bag. Put the plastic- covered hand into the bag with the shortening. Knead the shortening to make sure the hand is completely surrounded by shortening.
  4. Wrap masking tape around the portion of the bag covering your wrist to seal the bag (optional).
  5. Cover your other hand with two plastic bags (without shortening).
  6. Place both hands simultaneously into the plastic container.
  7. Have another group member time how long you can keep each hand under water.
  8. Allow everyone in your group to have a turn.
  9. Remove the bags from your hands and seal the bags so that water won’t get in. Attach weights to the outer bag of each “glove.”
  10. Put the bags into the bucket of water. Record how much weight each bag can hold before it sinks to the bottom.

Data:

Table 1: Amount of time hands are in water

Student Name / Time-shortening hand / Time- non-shortening hand

Table 2: Amount of weight until it sinks

Amount of weight added before it sank

“Glove” with shortening
“Glove without shortening.

Analysis:

  1. Which hand was the control in your experiment?
  1. Which hand were you able to keep in the cold water longer?
  1. What would the shortening represent on an Arctic animal?
  1. What “glove” held more weight? Why?
  1. So what other advantages would blubber give an ocean animal?
  1. Create a bar graph from data Table 1. Be sure make a key that shows which color represents which hand.

Conclusion: Write something new you learned today.

Background Reading for teachers- could be given to students at the end and used for discussion.

Seals are mammals, just like you or your pet dog or cat. They are “warm blooded” and must be able to protect themselves against the cold water in the polar regions. The water in the Antarctic and Arctic is about 1.8 degrees below freezing and you would only survive 1-2 minutes in that temperature without protection. But, seals do very well in these conditions. How do they do that?

If the answer was to simply wrap them in a layer of blubber, then the problem would be solved and we’d be done with this discussion. Blubber makes an excellent insulator and can easily protect the animal against the cold water. However, when you exercise in the cold, like when you ski or snowboard, you can unzip your parka if you get too warm. There are no zippers on seal blubber. What happens if a seal gets too hot? What do you do about all that blubber?

This brings up perhaps the most important part about “staying warm in a cold climate.” The real issue is how to thermoregulate your temperature- that is, to be able to control body temperature so that it remains constant whether you need to cool down or warm up. Blubber is the answer to this problem.

Blubber is not just a fat layer like you would see on a steak or in bacon. Blubber has structure; it is an organ. Think about a loofah sponge. Blubber is like that with a protein matrix making up the loofah and then the animal fills or removes lipid (fat) from the protein sponge. The sponge itself never really changes. When you cook bacon, the fat melts and forms a gel in your frying pan when it cools. If you cook a piece of blubber, some of the lipid comes out, but the blubber still sits there. The protein sponge and most of the lipid is still there.

As it turns out, blubber is not only used as a good thermal blanket, but it is also a store of nutrition (lipid), it is a water source (water is a waste product when the animal uses the lipid for energy), it acts in the control of buoyancy (it floats). And it helps streamline the outside of the animal. So, you can see, keeping warm is only one part of how blubber works.

So, how does the seal cool down? Basically, it has blood vessels that go through the blubber out to the skin. If the seal needs to lose heat, it opens up those blood vessels and the animal pumps warm blood out to the cold skin. Seals can warm up their skin enough to actually melt their way into the ice and create great clouds of steam. If they need to stay warm, then they keep the warm blood inside the blubber and the skin stays cold enough for the animal to be completely covered in snow and not melt any of it.

The point is that blubber is dynamic and is an organ….. it is important for the animal at many different levels, including staying warm.