Experiment: How do sharks swim?

Materials: Empty paper towel tube, scissors, balloon, large clear bowl, water and cooking oil.

Process: Cut the paper towel tube into two equal parts. Fill the bowl with water. Place one paper tube on the top of the bowl of water and observe.

Remove the paper tube. Fill the balloon with cooking oil and tie shut. Place the filled balloon into the second paper tube. Place the paper tube on the top of the bowl of water and observe.

Result: The tube of paper fills with water and sinks, but the tube with the balloon filled with oil floats. The oil in the balloon filed tube represents the oil in a shark.

A sharks’ liver has two parts filled with oil and fat. Oil and fat are lighter than water and thus float. The shark’s liver is 30 percent of the sharks’ weight thus the buoyancy helps them to float.