Ch. 5: Freezing Crows Teacher Sheet

Ch. 5: Freezing Crows Teacher Sheet


The "Freezing Crows" chapter explores the idea of de-extinction by using the DNA found in frozen tissue collections and tells the story of the conservation efforts to save the Hawaiian crow that is now extinct.  This teacher sheet provides background information and answers to questions on the student sheet.

There are many key terms introduced in this chapter that students may not be familiar with. If there are any terms missing on this sheet that you think the students should know, please add them. Use the resources provided to familiarize yourself with this chapter and the concepts presented. The takeaway points of this chapter include:

  • This chapter introduces the sources of frozen tissue samples found in the American Museum of Natural History and the Frozen Zoo in San Diego. This chapter also introduces the concept of de-extinction and that DNA is essential for this process.
  • There is an emphasis on the study of DNA and how it has furthered our understanding of evolution, biochemistry, population genetics, and captive breeding. 
  • A good ethical question brought up in this chapter is: Will saving DNA or genes really save these organisms? One argument is that the essence of the organism is preserved in how the organism interacts with its environment. The blueprint or code is in the DNA but how the DNA is expressed due to the environment is what makes a bee a bee. As it is said in the book, “if you plop a gene down on the moon, absolutely nothing happens.” The Introduction to Genetics sheet will review this concept and it is important that the students understand the central dogma to understand this argument.
  • The story of the extinction of the Hawaiian crow is important in that DNA samples of these crows are found in the Frozen Zoo and serve as a potential for de-extinction and how this can serve future conservation efforts.
  • The story of the Hawaiian crow also brings up another good point about how important the environment is to the behavior of these animals. The captive population would not learn the same survival skills as they would in their native environment. If that’s the case, then is it ethical to try to conserve them and, especially in the future, resurrect an organism whose habitat no longer exists?

Key Terms

  • Frozen Zoo – storage of frozen tissue samples from threatened and extinct animals at the San Diego Zoo
  • De-extinction – resurrecting extinct organisms 
  • Captive breeding – wild population captured and held in a highly maintained environment to ensure their survival in hopes of returning them to the wild again


1. In your own words, explain the dilemma in this chapter.
Answers may vary. Encourage your students to explain their answers.

2. What was the most interesting thing you discovered in this chapter?
Answers may vary. Encourage your students to explain their answers.

3. What was confusing?
Answers may vary. Encourage students to explain their answers.

4. The American Museum of Natural History (AMNH) has one of the world’s largest cryogenically frozen tissue sample collections. What is the purpose of freezing tissue samples?
The freezing of tissue samples from the last survivors of a species or endangered species will save their DNA for the future. DNA is the genetic code of a species and can provide information for the future of science and de-extinction. 

5. What is the Frozen Zoo? What is its goal?
Like the AMNH, the Frozen Zoo has frozen tissue samples as a resource for conservation efforts and evolutionary biology. 

6. Give a brief history of the 'alalā or Hawaiian crow. How did the population become threatened and then extinct? 
These were native birds in Hawaii that became extinct in the wild due to human presence.

7. What were the issues when trying to introduce captive birds into the wild?
This chapter focuses on the idea of how the environment really reinforces the behavior of species in the wild and how breeding animals in a captive environment can harm their transition back into the wild.

8. Research any additional information out there on the Hawaiian crows. What efforts are being made to reintroduce them back into the wild?
The crows became extinct in the wild. Captive breeding programs were underway that were not successful at first; however, efforts in 2017 reintroduced some into the wild and have been doing better.

This teacher sheet is a part of the Resurrection Science lesson.

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