Teacher Procedure:
1. Ask your students, "How might sharks detect prey? How do their senses compare to ours?" Begin your discussion about shark senses by explaining the lateral line and hearing to your students.(See Teacher Background.) Both of these senses help the shark by detecting movement or vibrations in the water. To help them gain a better understanding of how water moves in a way that sharks can detect, try the following activity. Place a clear shallow container such as a glass baking pan filled with about 1 inch of water on top of an overhead. Try dropping a variety of small objects such as a paper clip or piece of rice into the water. Or ask one of your students to lightly place a finger in the water. Your students will be able to observe that even the smallest objects create visible waves. Ask the students to imagine what it would be like to be able to detect that amount of movement without using your eyes from over 600 feet away as the shark can. Help them understand how far 600 feet is by comparing it to another location in your school such as the principal's office or the playground.

2. By comparing our sense of smell to that of sharks', your students will develop an idea of just how keenly sharks can smell. Tie string to the end of your "fishing pole" and attach a small towel or rag. Create your smell target (the prey) by soaking the towel in a strong smelling nontoxic solution such as vinegar, perfume, or an extract. Have one child hold the pole and blindfold another child instructing him or her to attempt to find the prey only by smell. (A variation of this activity is to soak cotton balls in the smell solution and hide them around the room. Depending on how difficult you would like to make it, children could be blindfolded.) Your students will probably find this difficult to do even when they are very close to the target. Compare the results of this experience with the sharks' ability to detect smell. (See Background.) In fact, sharks can detect a few drops of blood in the amount of water it takes to fill a swimming pool.

3. Discuss sharks' sense of sight with the children using the Backgrounder. Ask leading questions to get them to consider how eyesight is adapted in sharks. For example, How well do you think sharks would be able to see above water? (Most likely, sharks would see poorly above water because their eyes are adapted to darker environments and it would not be a necessary adaptation.) Why might some sharks have bigger eyes than others? (Some sharks that live in deep waters have larger eyes in order to take in more light.)

4. Challenge your students to hypothesize the order in which sharks might use their senses to find their prey. For example, "Which sense might first alert the shark that prey is nearby?" You might have the children role-play a scenario in which the shark finds food. For example, place a plastic fish or picture of a fish in a central location in your classroom to represent the shark's prey. Assign different children to take on the role of each of the senses — smell, hearing, sight, lateral line and the ampullae of Lorenzini. Ask them to stand in order in comparison to the fish. You may need to review some of the Background information. (Generally, a shark will first locate its prey through hearing or the lateral line, then will home in with smell, sight and, finally, the ampullae of Lorenzini — for more information on the ampullae of Lorenzini, view the Pretty Smart for a Hammerhead lesson.)

Extension Activities:
Now that you've investigated the similarities in sharks, investigate the differences in the Mysteries of Apo Island interactive. Recommended for advanced 5th grade students.

Outside Resources
The Shark Watchers's Guide.
By Guido Dingerkus. New York: Julian Messner, 1985.

Shark: Eyewitness Books
By Miranda MacQuitty. New York: Alfred A. Knopf, 1992.

Zoobooks 2: Sharks
By John Bonnett Wexo. San Diego: Wildlife Education, Ltd., 1983.

The Jaws of Death: Shark as Predator, Man as Prey
By Xavier Maniguet. New York: Sheridan House,1991.