Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS
SAF Archives  search ask the scientists in the classroom cool science
Guide Index

Shark Trackers

Hidden Depths

Shell Game

Spineless, But Smart

Whale Warning

Viewer Challenge
in the classroom

Creatures of the Deep: Whale Warning

When whales became trapped in fishing nets off Newfoundland, rescuer Jon Lien rushed to free them. Lien then devised an audible alarm to put on the nets that would warn the whales, but not the fish. Now that Canada has placed a moratorium on cod fishing, the whales have the ocean to themselves. Scientists are taking advantage of the temporary respite to find out more about how whales hear. Join Frontiers as Lien and the crew climb inside a whale for an anatomy lesson on whale ears.

Curriculum Links
Activity 1: Prints of Whales
Activity 2: At Issue: Consequences of Overfishing
Behind the Scenes with Frontiers
Did You Know?




endangered species,
habitat destruction


marine mammals




Most of us will probably never have to wrestle with a trapped whale in ocean waters, as does Jon Lien, seen on Frontiers, so it's hard to imagine the real size of a whale. This activity will give you an opportunity to experience the relative size of these giant marine mammals.


  1. kite string or masking tape

  2. wooden stakes

  3. 3'' by 5'' cards

  4. yard or meter stick

  5. chalk or spray paint (optional)

Create a whale-sized drawing from a small-scale diagram to envision the true size of whales, while also learning about scale.


  1. Download and photocopy and enlarge the grid for this activity on a copier, if possible.

  2. Divide into cooperative teams of three students each. Each team will be responsible for one grid sector.

  3. Label the grid along the top and side with letter and number designations, like those on street maps. Each grid on the whale graph represents a 5' by 5' area or 25 square feet, so you will need to make a 1/5-scale ruler to accurately measure within the graph. Label each grid sector with index cards or Post-it's.

  4. Measure the size of the blue whale on the graph and record its length and height on a sheet of paper. Convert these measurements to the actual size.

  5. Choose one of the whales to draw at full size. Go outside to a football field or parking lot or, if appropriate and large enough, use the cafeteria or gym.

  6. To set up a grid that will contain the life-sized whale drawing, you will need to scale up the graph. Outside, use stakes to plot the graph corners (use masking tape if done indoors), then connect with string or draw lines with builder's chalk until you have a life-sized grid system. Place the grid labels in the appropriate squares on the ground; place weights over the cards so they don't blow away.

  7. Work one grid at a time. Use your scale ruler and the drawing to plot stake positions along the lines running through your grid. Transfer those positions to the ground using the yardstick. Mark the ground using chalk or stakes where required. Connect the marks with string or masking tape. Stakes should be placed one linear foot apart except in the case of sharp curves.

  8. When all grids are complete, remove the grid string. Just how big is the whale? You may want to reproduce the whale drawings to their natural scale on the grass, a parking lot, or an outside wall of the school or other building (with permission). Drawings can be made permanent with paint or temporary with chalk. You can also use rolls of bulletin board paper; draw on the sections and tape them together.

  9. Try to express the size of your whale by comparing it to different items and quantities that could fit inside the shape. How does the size of the whale compare to a small dinosaur or living large mammal like an elephant, for example? How many students will fit inside the whale drawing?

  10. It has been said that the heart of a blue whale is the size of a VW bug! If the life-sized drawing is made in a parking lot, conduct a dramatic demonstration by having a teacher or other adult at your school drive a car into it, for comparison.

About the grid for this activity:

Adult humpbacks (top whale) can measure from 30 to 50 feet in length; though massive in size, the humpback is still only about half as big as the blue whale (bottom whale), the largest of all mammals.

 whale graph


This segment of Frontiers provides an excellent opportunity to discuss real-life dilemmas about economic and environmental issues. Overfishing is a complex problem that touches the economic and cultural fabric of life in Newfoundland, where fishing has been a way of life since the area was settled. Fishermen there are struggling with the devastating loss of a way of life. However, the long-range picture is even bleaker: if fishing continued, there would be no more fish.

  1. Do you think the moratorium on fishing in these waters is justified?

  2. What do you think the government should do, if anything, for the fishermen who have been deprived of a living?

  3. Jon Lien believes that "fishing will come back." Do you agree? Why or why not?

  4. The problem of overfishing is not limited to the Grand Banks off Newfoundland. The Georges Bank off Nantucket has also been closed indefinitely. What are the events that led to the closing of these fishing grounds of eastern North America? Can fishing be restored? Explain why or why not.

  5. Other problems in the marine environment have developed near the coastal northwestern regions of the United States and other areas where the ecosystem is out of balance. Can you find evidence of other current problems, such as dolphins trapped in tuna nets, that involve the environment and economics?


Filming at sea presents many challenges and hazards for crew and subject. Shooting the whale story meant working in subfreezing water and exploring the anatomy of a whale. Capturing the shark story meant being in the presence of sharks while operating an underwater camera. But to get the story in Monterey Bay, the crew had to observe the sea creatures from the bowels of the research boat, where the motion of the sea is most unpleasant. To the credit of its intrepid crew and host, Frontiers is the first TV program to film an exploration of the middle depths here.


  • Scientists theorize that the reason people might have a natural response to whale songs is because whales hear sounds at a frequency identical to the frequency heard by humans.

  • Humpbacks can sing complex songs lasting 30 minutes. To remember the phrases and themes of their songs, humpbacks may rely on rhymes at regular intervals. Scientists have also found that humpback songs change from year to year.

  • In working with orcas, biologist John Ford learned that each pod of orcas has its own dialect or speech pattern. Minor changes occur as dialects are passed from generation to generation.

  • Some marine mammals can dive to extraordinary depths, aided by the mammalian diving response (MDR), a combination of features that conserve energy and slow down metabolism.

  • With practice, most humans can hold their breath for one minute at the most. But the world record holder is the sperm whale, which can stay underwater on a single breath for over an hour!


Scientific American Frontiers
Fall 1990 to Spring 2000
Sponsored by GTE Corporation,
now a part of Verizon Communications Inc.