Nurse sharks live in warm, shallow waters in the Atlantic, Pacific, and Indian oceans. Nurse sharks' mating behaviors, like those of other sharks, are largely unknown to scientists. Crittercam is helping to change this, as scientists are using the camera to learn about how, where, and when the sharks mate.

Students will learn some basic information about nurse sharks and see photographs of scientists conducting nurse shark studies (from articles such as Crittercams Provide Insights into Nurse Shark Behavior). Students will work in groups to draw pictures of discoveries that scientists have made about nurse shark mating and reproduction, and they will consider the potential benefits of these studies for ocean conservation.

Geography, life sciences

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

Two to three hours

• Computer with Internet access
• Drawing materials, including construction paper and crayons or colored pencils

Students will

• identify nurse sharks' geographical range;
• list nurse shark behaviors that scientists might want to study;
• read and answer questions about nurse shark mating and reproduction;
• discuss how Crittercam might help scientists learn more about nurse shark mating behavior;
• look at photographs of National Geographic scientists studying nurse sharks, and answer questions about what they see;
• discuss the potential benefits of these studies for ocean conservation;
• draw pictures of discoveries that scientists have made about nurse shark mating and reproduction; and
• share their pictures with the class.

Have students look at the pictures of nurse sharks at Elasmodiver or The Vibrant Sea. Ask them what they notice about this type of shark just from looking at the picture. Do nurse sharks appear to live in deep or shallow water?

Have students go to Animal Diversity Web. Ask them to read about nurse sharks under "Geographic Range." Have a student volunteer demonstrate the nurse shark's broad habitat on a wall map or in an atlas. Students should understand that nurse sharks can be found throughout the world's warm waters.

Ask students, either in groups, in pairs, or individually, to list as many shark behaviors as they can think of that scientists might want to study.

After they have had a minute or two to write their lists, discuss their ideas as a class and allow them to add behaviors to their lists that they may have missed. Their lists should at least include eating, socializing, mating, caring for young, defending themselves, playing, and resting.

Have students return to Animal Diversity Web and scroll down to "Reproduction." Have older (5th grade) or more advanced students read this paragraph, and paraphrase it for younger (3rd or 4th grade) students. Help them answer these questions about the paragraph:

• Do we know much about nurse shark mating habits?
• What are two ways that nurse shark eggs develop? [Note: The names for these methods aren't important, just the concepts.]
• How many pups do nurse sharks tend to have at one time?

Explain to the class that nurse shark mating behavior (as with all sharks) is largely a mystery to scientists, but that they are trying to use Crittercam to learn more about how and where nurse sharks mate. Ask students how they think Crittercam might help us learn about nurse shark mating behaviors. (If students have not yet been introduced to Crittercam, they can learn about it at the Crittercam Chronicles.)

Help students identify the Florida Keys on a United States wall map or at the Xpeditions atlas map of Florida. Explain that National Geographic scientists have been studying nurse sharks in the Florida Keys for about 30 years and are trying to learn about their mating behavior.

Each of the three National Geographic News articles below contains a "Shark Photo Gallery" link at the top. Have students go to each article and link to the photo gallery. Tell them that these photographs were taken in the Florida Keys as scientists were studying nurse shark mating and other behaviors. Ask students to write answers to the questions that go along with each article's photo gallery.

Scientists Study Nurse Shark Mating Habits

• Where does the tag sit on the shark? Does the shark seem to notice it?
• Why do you think they tag nurse sharks anyway?
• Have many nurse sharks in this area been tagged?
• Do fishermen like catching nurse sharks? What do they generally do with them?

Researchers Tag Sharks to Study Breeding Habits

• What do they use the net for?
• Where do the researchers take the sharks, or do they keep them in the water?
• What two types of tags are used to identify nurse sharks?
• What does the researcher do to the shark just before releasing it? Why?

Crittercams Provide Insights into Nurse Shark Behavior

• Why do researchers use kayaks?
• Do the scientists ever have to fix or adjust Crittercam?

Write the word "conservation" on the board and ask students to explain its meaning. What does it mean to conserve an animal species or an ecosystem, such as a certain part of the ocean? Why is conservation important?

Ask the class how they think knowing more about nurse shark mating and reproduction might help shark and ocean conservation projects. How might knowing about nurse shark mating behaviors help us to conserve the ocean ecosystem? How might the scientific studies that they have learned about help keep the world's oceans healthy? (Make sure students understand that most species of nurse sharks are not endangered, but that they are an essential part of the ecosystem and should therefore be protected.)

Below are nine important points and findings from recent National Geographic studies on nurse shark reproduction in the Florida Keys.

• The same nurse sharks return each year to mate in the same place in the Florida Keys.
• Scientists have tagged sharks and measured the DNA in their blood to see which sharks are related to each other.
• Sharks mate in shallow water.
• Males swim after females, but most females are not interested in mating.
• Females probably try to select the "best" male to breed with–they are very picky!
• Nurse sharks are not ready to mate until they are 18–24 years old.
• A female can give birth to 25 to 35 pups from four or five different male sharks at the same time.
• Crittercam does not bother the sharks—they still mate with the camera attached to their fins.

Divide the class into nine groups and give each group a strip of paper with one of these facts or findings written on it.

Ask each group to discuss this question: Why is it important for scientists to know this information about nurse sharks?

Ask groups to draw pictures illustrating the fact sheet they have been given. Their pictures should be large enough so that the rest of the class will see and understand them when groups share with the class.

Have groups take turns sharing their pictures with the class. As they share, ask them to pretend that they are scientists who are conducting research on nurse sharks.

After each group has described its picture and read the information on its strip of paper, ask group members to explain why this is important information for scientists to know and to describe how it might help scientists in future research on nurse sharks.

Have students pretend that they are scientists who are planning to use Crittercam to study nurse sharks. Ask them to diagram a nurse shark (they can model their diagrams after the pictures on any of the above Web sites) with a Crittercam on its back—they can learn about how Crittercams are built for different animals at Crittercam Chronicles. When they are finished with their diagrams, ask them to write paragraphs describing one aspect that they would like to study, explaining how Crittercam will help them get the information they are looking for and discussing the potential difficulties they might have with Crittercam (e.g., the camera falling off).

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.

Animal Diversity Web: Ginglymostoma cirratum
Elasmodiver: Nurse Shark
Enchanted Learning: Nurse Shark
National Geographic News: Crittercams Provide Insights into Nurse Shark Behavior
National Geographic News: Researchers Tag Sharks to Study Breeding Habits
National Geographic News: Scientists Study Nurse Shark Mating Habits
National Geographic: Crittercam Chronicles
National Geographic: Xpeditions Atlas
The Vibrant Sea: Nurse Shark