Marine mammals spend all or most of their time in ocean water. What keeps them warm? If you were swimming in the warm waters off the coast of the Bahamas, it might seem a crazy question to ask. However, at some point, your body would get cold! What if you were to dive into the icy waters of the Arctic Ocean? The cold waters would be almost unbearable for most humans. So how do whales, dolphins, seals and other marine mammals keep from being cold? One simple word: BLUBBER!
For these mammals, body temperature must remain between 95-100.4 degrees Fahrenheit (35-38 degrees Celsius). Blubber is a thick layer of fat cells beneath the surface of the skin that preserves heat and keeps body temperatures in the ideal range. It's the perfect insulator! This layer of fat is very thick! For example, a dolphin has a layer of blubber around .7” and the fat layer for sperm whales is between 1-2ft thick. In addition to serving as an insulator, blubber is also used to store fat, as an energy source and for buoyancy.
Scientists have recently discovered a downside to this layer of insulation. Blubber also stores and/or absorbs harmful chemicals and toxins that are polluting the earth's waters. These toxic chemicals are feared to be passed from parents to offspring. Whale blubber is documented to have higher levels of mercury, PCB’s and pesticides!
Activity
Materials: white model magic, buckets, and ice water
Procedure:
- Brainstorm ways humans stay warm. Now, lead a discussion about how they think marine mammals survive in their ocean habitats.
- Discuss with students what they think will happen if they plunge their finger into a bucket of ice water. Record results.
- If you have a brave student, you can let them test the frigid water before continuing on with the activity.
- Now discuss with students what they think will happen if a finger covered in"blubber" is plunged into a bucket of ice water. Record your results.
- Distribute balls of model magic to each student. Ask them to flatten each ball using the heel of their hand. Now, have them wrap their index finger completely.
- Once covered, students will take turns plunging their "blubber finger" into the icy water.
- Ask students to form an opinion about how blubber works and add to a class wallwisher. Each student should form a response.
Conclusions: All marine mammmals, like other mammals, are warm-blooded. Their body temperature remains constant and does not adjust to changes in the surrounding temperature. Blubber provides the perfect layer of insulation to keep them warm. It's their built in "snuggy"!
To make this super fun, you could record the demonstratin with a Flip camera and post on a class wiki or create a slideshow using Google Docs. In addition, you could easily post student responses there. Be creative have fun learning!
Monday, July 12, 2010 at 8:16PM