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Conversation 2 - Discuss whales’ breath

Narrator: Listen to a conversation between a student and his biology professor.

Student: Well, you know, I am writing that paper about whales and the path they travel as they swim through the ocean, their migration patterns.

Professor: Yes. I remember.

Student: And well, I was thinking about it and I realized I don’t understand how they hold their breath underwater. It’s a little crazy for me to be writing about migration patterns without actually knowing how they stay underwater for so long.

Professor: Did you do any research to find out how they do it?

Student: Yeah, I did. I searched on the internet and there was a lot of information about whales, their habitats, the way they communicate, you know, their songs.

But if there was anything about whales and how they hold their breath, I missed it.

I’ve got a bunch of books. Actually, I have got so much information, it’s a little overwhelming.

Professor: I am surprised there is nothing about it in any of those books.

Student: Well, to be honest, l’ve only skimmed them so far. I am still working on finding sources.

Professor: OK. I know I encourage everyone in class to look at a substantial number of sources, but I don’t want you to get overwhelmed. Looking at a number of sources gives you a good knowledge base, but students only have a limited amount of time to work on each paper. I don’t expect you to read a dozen books on whales for this assignment. Focus on just a few.

Student: Ok. Thanks.

Professor: You know, since you are already here. I can give you a quick summary of how whales hold their breath underwater. It’s just a matter of certain adaptations in their anatomies, specifically in their circulatory system.

Student: So the blood flow is what makes the difference?

Professor: Yes, and in a couple of ways. First, blood makes up a larger share of a whale’s weight than in other mammals.

Student: So they can store more oxygen because they have more blood?

Professor: Yes, but that’s only part of it. They also have a greater capacity than land animals to store oxygen in their blood.

Student: So how does having more oxygen in their blood help them stay underwater longer?

Professor: It’s the way the whale’s blood carries oxygen to the rest of its body.

Whales carefully conserve their oxygen when underwater in a couple of ways.

When a whale dives, its metabolic rate drops, causing its heartbeat to slow down.

And the blood flow to its muscles and some of its non-vital organs, like its kidneys, is also cut off. A whale’s muscles and non-vital organs are able to function without oxygen for an extended period of time.

Student: I see. Well, now I can concentrate on my topic.