By Annette Gulati
Whales and many other marine mammals live in cold waters. But they don't have fur, so how do they stay warm?
Try this to find out. Coat one of your fingers with a thick layer of soft margarine or peanut butter. Dip that finger and one other finger into ice water. Why does one finger feel warmer than the other? Think of your own best answer, then read ours below.
Photo by Nannette Bedway