Joe Reeves, age 10, of Winnipeg, Manitoba, Canada, for his question:

HOW LONG CAN WHALES STAY UNDERWATER?

The largest whale is also the largest animal that has ever lived. The blue whale, which grows to be 95 feet long and weighs 150 tons, is bigger than elephants or even the prehistoric dinosaurs. A newborn baby blue whale can be 23 feet long and weigh three tons.

Whales are not fish, they are mammals. Even though they live in the water, they must breathe air. They will drown if they become trapped underwater.

The whale is able to hold his breath underwater for some time. The baleen whales, which have no teeth, can stay underwater only from five to 10 minutes. Sperm whales, on the other hand, can stay submerged from between 45 minutes and one hour. After having held his breath underwater for some time, the air becomes hot and full of moisture. When it is released at the surface, it often condenses to form a spout or column of fog.