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Ch. 50 - Behavioral Ecology
Freeman - Biological Science 8th Edition
Freeman8th EditionBiological ScienceISBN: 9780138276263Not the one you use?Change textbook
All textbooksFreeman 8th EditionCh. 50 - Behavioral EcologyProblem 12
Chapter 50, Problem 12

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Mass strandings of whales occur on beaches near military exercises where sonar is used, raising concerns about the effects of human-generated underwater sounds on animal behavior. Scientists are collecting behavioral data on several species of whales to find out how sonar affects them.
Researchers followed tagged blue whales to observe how they respond to simulated military sonar—using sound levels much lower than those typically used during military exercises. Analyze the sample of data below for one individual blue whale and summarize the behavioral effect of the sound exposure.

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Examine the graph to understand the relationship between the depth of the whale below the surface and time. The graph shows the whale's behavior over a period of 120 minutes.
Identify the two main activities of the whale: breathing and foraging. Breathing occurs near the surface (0 meters), while foraging occurs at greater depths (around 150 meters).
Notice the section labeled 'Sound exposure' between approximately 60 and 90 minutes. During this period, the whale's behavior changes, as indicated by the purple line.
Compare the whale's behavior before, during, and after the sound exposure. Before exposure, the whale shows a regular pattern of diving and surfacing. During exposure, the whale's diving pattern becomes irregular, with shallower dives and more frequent surfacing.
Summarize the behavioral effect: The sound exposure appears to disrupt the whale's normal foraging behavior, causing it to dive less deeply and surface more frequently, indicating a potential stress response to the sonar.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Behavioral Responses to Sound Exposure

Marine mammals, including blue whales, exhibit specific behavioral responses to underwater sounds, particularly those generated by human activities like sonar. These responses can include changes in diving patterns, foraging behavior, and social interactions. Understanding these responses is crucial for assessing the impact of anthropogenic noise on whale populations and their ecological roles.
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Foraging and Breathing Patterns

Foraging and breathing are essential behaviors for blue whales, which typically dive to significant depths to feed and surface to breathe. The graph illustrates these patterns, showing regular cycles of depth changes associated with foraging and breathing. Disruptions in these patterns due to sound exposure can indicate stress or altered behavior, which may affect the whale's ability to feed and survive.
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Impact of Sonar on Marine Life

Sonar, particularly military sonar, can produce intense sound waves that may interfere with the natural behaviors of marine life. Research indicates that exposure to sonar can lead to disorientation, altered communication, and even strandings in some species. Understanding the relationship between sonar exposure and whale behavior is vital for developing conservation strategies and mitigating negative impacts on marine ecosystems.
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Related Practice
Textbook Question

Hamilton's rule states that an altruistic allele could spread in a population if Br > C, where B represents the fitness benefit to the recipient, r is the coefficient of relatedness between altruist and recipient, and C represents the fitness cost to the altruist. If r = 0.5 between the altruist and the recipient, what would the ratio of costs to benefits have to be for the altruistic allele to spread?

a. C/ B > 0.5

b. C/ B > 0

c. C/ B < 0.5

d. C/ B < 0

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Textbook Question

Evolutionary biologist Hopi Hoekstra and colleagues have hypothesized that the burrow-digging behavior of mice (and the resulting shape of their underground burrows) is heritable—innate and not learned. Design an experiment to test this hypothesis.

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Textbook Question

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Mass strandings of whales occur on beaches near military exercises where sonar is used, raising concerns about the effects of human-generated underwater sounds on animal behavior. Scientists are collecting behavioral data on several species of whales to find out how sonar affects them.

Whales communicate with one another using sound. What is one benefit and one cost to whales of using sound to communicate underwater?

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Textbook Question

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Mass strandings of whales occur on beaches near military exercises where sonar is used, raising concerns about the effects of human-generated underwater sounds on animal behavior. Scientists are collecting behavioral data on several species of whales to find out how sonar affects them.

Using the graph, estimate the number of minutes of foraging per hour before and after the sound exposure. Then predict the effect of sonar on the fitness of blue whales. Explain your reasoning.

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Textbook Question

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Mass strandings of whales occur on beaches near military exercises where sonar is used, raising concerns about the effects of human-generated underwater sounds on animal behavior. Scientists are collecting behavioral data on several species of whales to find out how sonar affects them.

Predict why the whale foraged at a depth of 100–170 m.

a. The whale learned to forage at this depth from its mother.

b. The whale had an innate instinct to feed at this depth.

c. The whale's food was most plentiful at this depth.

d. The whale could not dive any deeper than this depth.

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Textbook Question

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Mass strandings of whales occur on beaches near military exercises where sonar is used, raising concerns about the effects of human-generated underwater sounds on animal behavior. Scientists are collecting behavioral data on several species of whales to find out how sonar affects them.

The researchers also measured the speed and direction of whale swimming in response to the sound exposure. Whales increase their speed and swim away from the direction of sound. Design a study to test the hypothesis that this behavior leads to beach strandings. Note that you will not receive permission to conduct the study if your actions are likely to cause strandings to occur.

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