Staying Warm in the Ocean:

Courtesy of NMSS

Background
Whales, and especially right whales, have a very low surface area to volume ratio. The right whale has a particular shape - a torpedo-like ("fusiform") body shape and reduced limbs. Over time this shape evolved into a large volume body with the least amount of exposed external appendages. Natural selection decreased the amount of surface area exposed to the external environment while increasing volume. Right whale adaptations include: a heavy, round body; short, stubby limbs; no dorsal fin; and a thick layer of blubber.

In this lesson, students predict and observe how water temperature can affect body temperature, depending on the shape and insulation of the body.

Look at a picture of a right whale. Describe its anatomy--the shape and size of its body, limbs, fins, etc. Have students brainstorm why they think the right whale has adapted to that shape?

Materials You Will Need

• hot and cold tap water
• a dishpan or bucket
• a thermometer
• 2 zip-lock sandwich bags
• 1 styrofoam cup
• 1 disposable plastic glove

Procedure

1. Fill the dishpan or bucket half full with cold water. This will be your "ocean."
2. Measure equal amounts of hot water for both sandwich bags and the glove. Tie or tape the glove to prevent leaks.
3. Take the temperature of the hot and cold water and record. Both bags and the glove should begin at the same temperature.
4. Place one of the bags of hot water inside a styrofoam cup and fold the top down around it to seal in the bag. Tape closed if necessary.
5. Place all three into the dishpan of cold water. Leave them in for five minutes.
6. While the students are waiting, have them predict what will happen. They should predict how the temperature of each of the three objects will change, and explain why.
7. After five minutes, remove the glove, the plain bag and the bag in the styrofoam cup. Take the bag out of the styrofoam cup. Take the temperature of the water inside each of the three objects. Compare these temperatures to those taken before submersion.

• After five minutes in the cold "ocean" water, which was the warmest, the coldest? Did it make a difference to place one bag into a styrofoam cup? Were your predictions accurate?
• Describe how each of the three items is similar or different from a whale's body.
• Why do you think we used a glove? (The glove is like an animal with long legs. It has a lot of surface area in relationship to its volume.)
• The styrofoam represents part of the anatomy of a whale. Which part?
• How is a plain sandwich bag like a whale's body?
• Brainstorm a list of mammals that live in the sea. How many of them have long legs? Where in the world's oceans do they live (arctic, temperate, tropic, coastal or open ocean)?

Research Question

• How does surface area and volume of an object affect its heat loss?