Abstract

Objective

In this project, you will test whether or not a layer of blubber is a helpful adaptation for cold-water environments.

Introduction

Do you ever wonder what makes each species of animal unique? Where does all of the diversity of life on this planet come from? The key to this puzzle is called evolution, which is the process by which groups of organisms change over time, from generation to generation, leading to the development of new species. The key to evolution is a process called natural selection, sometimes referred to as "survival of the fittest." Natural selection presents a challenge to all the different types in a population, allowing those who overcome the challenge and reproduce, to pass on useful traits to their descendants, which increases that population's fitness and survival.

Evolution and natural selection were first proposed by Charles Darwin. While on a long voyage on a ship named the HMS Beagle, he was able to observe and document many useful traits, called adaptations, of animals he saw. An adaptation is a trait that comes in handy when an organism has to deal with a challenge. Adaptations take many generations to appear in a population, but the results are worth it. Many of the changes that lead to an adaptation are random, but natural selection picks through and determines which adaptations will continue from generation to generation.

To experience some adaptations that have increased the fitness of an organism, act out the three behaviors below:

• Flap your arms like wings - The wings of birds are an adaptation for flight. When the bones of the wing are spread out, they create a skeleton with a large surface area for an aerodynamically shaped wing, which means it is shaped for flight. When covered with feathers, the wing produces lift and can also be used to glide. Birds also have hollow bones that keep their body weight low, large chest muscles for flapping, and a large breast plate where the chest muscles attach. As you flap your arms, you may notice that your chest muscles begin to feel tired. Umm, you can stop now...don't overdo it!
  
• Walk straight and tall - Walking upright, or being bipedal, is a special adaptation of hominids, a special group of primates that includes humans (Homo sapiens) and their close relatives (like Neanderthals or Australopithecus). Other primates, like chimpanzees and gorillas, must use their forearms when walking, and do not walk upright. This adaptation gave hominids an advantage in interacting with the environment, and might have led to the development of larger brain sizes in our hominid ancestors. Scientists believe that walking upright was an adaptive trait that allowed hominids eventually to become better hunters and gatherers, and to develop tools to use for these activities. As you walk around, notice that your arms are free to move, how quickly you can observe your environment, and how quickly and easily you can move and change direction.
  
• Fold your arms and shiver - Shivering is an adaptation shared by other mammals to stay warm when temperatures become cooler. Mammals are warm-blooded, meaning our metabolism makes up a lot of our body heat, and we do not get most of our warmth from the environment. However, the environment can still affect us. Sometimes we get chilly, so shivering produces body movements, which briefly speeds up our metabolism, warming us up. It is also a good signal to the brain to find a warmer place to go! Now go grab a blanket, silly!

Adaptations are all around you, and once you start to notice them, you just can't stop! In this project, you will investigate an important adaptation for marine mammals, called blubber, a layer of fat beneath the skin that is used as insulation and keeps the body warm in cold temperatures. Blubber is commonly found in mammals that have adapted to life in a cold-water environment, like whales, seals, sea lions, and polar bears. You will use a layer of shortening on your skin to model the adaptation of blubber. Will the extra layer of fat help you stay in the cold longer?

Terms, Concepts, and Questions to Start Background Research

To do this type of experiment, you should know what the following terms mean. Have an adult help you search the Internet or take you to your local library to find out more!

• Diversity
• Evolution
• Generation
• Natural selection
• Descendant
• Adaptation
• Metabolism
• Blubber

• What is an adaptation?
• How does blubber keep polar bears warm?
• What other marine animals use blubber as an adaptation?

Bibliography

• The original source of this project is the San Diego Zoo:
  San Diego Zoo. (2007). San Diego Zoo's Science Project: How Do Polar Bbbears Stay Wwwarm? Zoological Society of San Diego, CA. Retrieved December 6, 2007 from http://www.sandiegozoo.org/education/science_polar_bear.html
• At Kimball's Biology Pages you can read about evolution and adaptation:
  Kimball, J. (2007). Evolution and Adaptation. Andover, MA: Kimball's Biology Pages Retrieved December 6, 2007 from http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Evolution.html
• You can also learn about evolution and adaptation from the "Understanding Evolution" website, a collaborative project of the University of California Museum of Paleontology and the National Center for Science Education:
  UCMP. (2006). Evolution 101: Adaptation. University of California Museum of Paleontology (UCMP), University of California, Berkeley; and the National Center for Science Education (NCSE). Retrieved December 6, 2007 from http://evolution.berkeley.edu/evosite/evo101/IIIE5Adaptation.shtml

Materials and Equipment

• Empty bowls (2)
• Cold water
• Warm water
• Ice cubes
• Shortening (like Crisco®)
• Paper towels
• Stopwatch
• Celsius thermometer
• A partner

Experimental Procedure

1. Fill two bowls with cold water and ice cubes.
2. Measure the temperature of the water with a thermometer. When the temperature levels off, the bowls are ready. Write down the temperature of the water in a data table like the one below.

   Water Bowl	Water Temperature (oCelsius)	Covered Finger Time (sec)	Uncovered Finger Time (sec)
   Ice-Cold
   Ice-Cold
   Ice-Cold
   AVERAGE
   Warm
   Warm
   Warm
   AVERAGE

3. Cover the pointer finger on one hand with a thick layer of shortening.
4. Have your partner prepare the stopwatch, and when he or she says go, put the pointer finger of each hand into one of the bowls of ice water.
5. Have your partner time how long you can leave each finger in the bowl, and write the results in a data table.
6. Wait until your fingers return to their normal color, then repeat steps 5-6 three times and average your results.
7. Switch partners and repeat steps 6 - 9.
8. Repeat the entire experiment with warm water. Predict whether you think you will see the same result.
9. Make a graph of your results. In which environment did the adaptation give a significant advantage?

Variations

Can you model other types of adaptations to show how they increase fitness? Here are some ideas:

• Plants - Some plants have waxy leaves, and some have regular leaves. Waxy leaves are common in plants that live in dry environments, and keep the plant from losing water. You can model the waxy coating of a leaf by covering a moist sponge with a layer of shortening. Will an uncovered sponge dry out before a covered sponge? Do waxy leaves resist drying out better than regular leaves?
• Long tails - animals with long tails often use them for balance. Make a model of a rat, monkey or other animal with a long tail. Can you use a balance test on your model to find out if the tail adds stability?
• Big ears - Animals that are nocturnal, or spend most of their wake hours at night, often have big ears. Can you do an experiment with ear cones to show how this adaptation can increase hearing ability? Why would this be useful for an animal that hunts at night?
• Webbed feet - Try the Science Buddies Experiment The Swimming Secrets of Duck Feet to see if duck feet can help you swim faster.

• For more science project ideas in this area of science, see Zoology Project Ideas.

Credits

Sara Agee, PhD, Science Buddies