Scientists believe that whales vocalize to locate one another, to find mates, and to socialize. Each whale species, like the orca, has its own set of sounds, and populations, or groups, of whales within the same species often make calls that differ from other populations. Whales also use their ability to emit sounds to help them navigate in a process called echolocation, in which the sounds bounce back to them from objects and the ocean floor.

Students will learn about the vocalizations of several whale species and the special calls of different populations of blue whales. They'll be asked to learn snippets of whale calls and to simulate whales trying to locate each other in the ocean. The students will conclude by drawing pictures of whales vocalizing and by writing captions explaining what their pictures show.

Geography, life sciences

Standard 8: "The characteristics and spatial distribution of ecosystems on Earth's surface"

Two to three hours

• Computer with Internet access

Students will

• read about blue whales, and hypothesize the reasons whales vocalize;
• listen to blue whale vocalizations and compare the differences between blue whale populations;
• listen to the vocalizations of other whale species, and compare them with each other;
• discuss the reasons for different species having different calls;
• view and discuss a diagram of echolocation;
• perform a simulation where they pretend to be whales of various species calling to each other;
• draw posters showing whales communicating; and
• write captions for their posters.

Have students go to this blue whale fact sheet and take turns reading the sentences describing blue whales. Make sure they realize that the picture of the blue whale, shown in the blue box, is not shown to scale—blue whales are much bigger than dolphins (shown in the upper right) and sea turtles (shown on the left). Tell the class that blue whales are so big that their hearts are the size of small cars!

Ask students to name some of the activities that whales do, and list their ideas on the board. They might mention feeding, socializing, mating, caring for young, and migrating.

Tell the class that whales, including blue whales, make sounds that originate in their heads and throats. Why do students think whales make sounds? What purposes might the sounds serve? Students should think about the reasons people and other animals make sounds and the reasons why whales might benefit from vocalizing rather than relying on visual signals from each other. Explain that since sound carries well through water (as children may have noticed in a lake or swimming pool), whales can send their sounds over long distances.

Explain to the class that scientists are still learning about the reasons whales make sounds, but they believe that whales use their calls to locate each other, to find mates, and to socialize. Mothers also use sounds to communicate with their offspring.

Have students listen to these blue whale vocalizations. Ask them to compare the vocalizations of these different groups of blue whales. Why do blue whales living in different areas have different calls?

Have students listen to the calls of other whale species at the following Web sites. As they listen, ask them to pay careful attention to the similarities and differences between calls of the same species and between the different species' calls.

NOAA: Humpback Whale Acoustics
NOAA: Whale Acoustics Project
Wild Killer Whale Adoption Program (Select "Biology & Research" and then "Whale Chat.")

Discuss the reasons why different whale species would have such different-sounding calls. Remind students of the reasons that whales make sounds, and ask them to think about how whales of the same species might locate each other in the ocean.

Is it good for the whales that their calls sound different from the calls of other whale species? Students should realize that these differences help whales identify members of their own species, with whom they'd want to mate and socialize.

Have students look at the first part of this first diagram of echolocation. Explain that this diagram shows the process by which a whale emits sounds to locate objects, such as fish. The sound waves bounce off the fish and echo back to the whale.

Explain that most, and perhaps all, whales are capable of echolocation. Why do students think this practice would benefit whales? What might it enable them to do? They should realize from the diagram that echolocation can help whales find food, navigate, and locate other objects in the ocean.

As an option, have students go to NOAA's Acoustic Monitoring Program: Sounds page to compare blue whale sounds with other sounds that have been recorded in the ocean. What are the main differences between the blue whale sounds and the other sounds?

Assign each student to one of these whale species: blue, fin, humpback, killer (orca). Make sure there are at least two students assigned to each species. Have students return to the Web sites above and listen again to the sounds of their assigned whale species. Ask them to memorize all or part of a whale call from their species.

Have students stand up and begin making their whale calls softly. Each student's goal will be to try to locate another "whale" of its own species. This may be challenging, but they should see if they can identify common patterns.

Let the simulation continue for about three minutes. As students locate their matches, have them continue "singing" to attract other members of the same species.

Discuss the purpose of the simulation. Can students understand why whales of different species benefit from having different calls? Can they understand why whales benefit from being able to make sounds in the ocean?

Divide the class into small groups so that each group has at least one person representing one of the different whale species used in the simulation.

Ask groups to draw posters showing their different whale species swimming in an ocean habitat. They can see what each whale looks like and get a sense of its size in relation to the other species by viewing the pictures at the Whale Acoustics Project. Students should label the whales on the poster.

Ask each student to think of a visual "code" that can represent their assigned whale species' call. The code may be a series of dots and dashes, a set of pictures, or a spectogram like the ones they've seen at the Web sites. Ask them to draw these codes next to their whale species on the poster. This will show the call that the whale is making.

Have groups write captions to explain what their posters show and, in particular, describe the sounds that the different whale species are making. Their captions should also explain the reasons why the whales are making these sounds.

Have students look at this diagram to see how an underwater microphone (hydrophone) can be attached to an anchor and used to pick up ocean sounds, including whale calls. The most important things for them to notice on the diagram are the hydrophone (right below the yellow float), the anchor, and the whale. The "T-waves" are produced by an underwater earthquake.

Explain that the sounds coming from the whale and other underwater sources are picked up by the hydrophone, which sends a signal to machines that record the sounds. This is one of the main ways that scientists record and learn about whale sounds.

Have students imagine that they are scientists who have equipment that can receive signals from this hydrophone. Ask them to write paragraphs describing what they might hear and explaining why the hydrophone is so useful in their research.

This material is based on work supported by the National Science Foundation under Grant No. 0229817.

Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

British Columbia Wild Killer Whale Adoption Program
Echolocation
NOAA: Acoustic Monitoring Program
National Parks Conservation Association: Blue Whale
Whale Acoustics Project
Wild Killer Whale Adoption Program: Select "Biology & Research" and then "Whale Chat."