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 listen to the vocalizations of several whale species and the special sounds of distinct blue whale populations. They'll consider why different whale species make different sounds, and they'll learn about the ways scientists are able to record these sounds. They will conclude by writing paragraphs as if they were scientists studying blue whale calls and describing their research process.

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

• list whale behaviors, and discuss how they think whales communicate;
• listen to and discuss whale vocalizations;
• read and answer questions about whale communication and echolocation;
• view and discuss a diagram of the hearing ranges of different whale species;
• view a diagram of a hydrophone, and discuss how scientists locate and record whale calls; and
• write paragraphs pretending to be scientists studying blue whale calls and explaining how they'll go about their research.

Ask students to think of some common whale behaviors, and list their ideas on the board. They should mention feeding, socializing, mating, caring for young, and migrating.

Ask students to picture whales doing these activities in their ocean habitat. Based on what students know about whale anatomy, how do they think these animals can communicate with one another? Are they nimble enough to use "sign language" with their flippers or to have sophisticated body language? Students will probably realize that whales must use another method of communication, and they may already know that whales communicate with sounds.

Have students go to the following Web sites to hear whale sounds. As they listen, ask them to pay careful attention to the similarities and differences between calls within the same species and between the different species' calls.

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

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?

Pose these questions to the class, and have students brainstorm them as a class or in small groups. Discuss their answers together:

• Why do you think whales make these sounds?
• Why do you think different populations within one whale species, such as the blue whale, have different types of calls?
• Why do you think different whale species have different calls? How might this benefit them?

Have students read the text at the following Web sites, and ask them to write answers to the questions below. Then discuss their answers as a class.

Communication and Echolocation in Marine Mammals
Echolocation (Look at the first part of the first diagram, showing the whale echolocating.)
MIT: Do Dolphins Sleep? Questions and Answers About the Sea

• What are some reasons why whales communicate with one another?
• What is echolocation, and why do whales use it? Do all whales seem to echolocate?
• Do scientists know everything about whale communication and echolocation, or are they still studying these phenomena?
• (If students are familiar with Crittercam): How might Crittercam help take the place of the "datalogger" in studying non-captive whales?

Have students go to the Acoustics Monitoring Program page and scroll down to the very bottom. Have them look at the chart of vocalization frequencies. Explain what the chart shows by telling them that the lower numbers (close to ten) represent very low-pitched sounds, and the higher numbers (close to 10,000) represent very high-pitched sounds. The dark lines next to each species represent the range of sounds that each species can hear.

If students compare the frequency range for humans with those of whales, they'll see that many whale species make sounds that are either too low or too high for people to hear. For example, blue whale sounds are so low that people can't hear them at all.

How, then, can we hear the blue whale sounds students have listened to earlier in the lesson? Ask students how they think this is possible, and then explain that scientists simply speed up the recordings until they are in the audible range, much as we could speed up a recording of an adult man until he sounds like a little child!

How can we locate whale sounds in the vast ocean? Explain that this is an area where military technology has helped scientific research. During the Cold War, in which the United States and the Soviet Union were engaged in ideological conflict, the United States installed underwater microphones (hydrophones) in special places in the ocean to detect the sound of Soviet submarines. Now these hydrophones can be used to listen to the sounds of whales in addition to the sounds of ships, underwater earthquakes, and other marine noises.

Explain that scientists have added more hydrophones to help listen to the sounds from a broader range of the ocean. Students can see a diagram of how these hydrophones are set up. They should be sure to notice 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.

Discuss as a class the techniques scientists use to study whale calls. Ask students to explain how they think a Crittercam with an audio recorder can help in these studies. (If they're not yet familiar with Crittercam, they can learn about it at Crittercam Chronicles.)

Ask students to imagine they are scientists who have been assigned the task of learning more about the calls and sounds of blue whales. Have them write paragraphs detailing:

• why whales make sounds;
• the technology they can use to learn more about whale sounds; and
• why it's useful to study whale sounds and how the information they gather can be useful.

Have students read the National Geographic News article Human Noise May Disturb Whales' "Love Songs". Ask them to write paragraphs explaining why scientists are concerned about the noise interference.

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
Communication and Echolocation in Marine Mammals
Echolocation
MIT: Do Dolphins Sleep? Questions and Answers About the Sea
NOAA: Whale Acoustics Project
National Geographic: Crittercam Chronicles