Cerullo Mary M. - The Truth About Great White Sharks

To Kay and Mim:
The one who raised me and
the one who took over the task...
-Mary M. Cerullo

To Adam and Dana
-Jeffrey L. Rotman

Chronicle Books LLC
680 Second Street
San Francisco,
California 94701
www.chroniclebooks.com/Kids

Text 2000 by Mary M. Cerullo.
Photographs 2000 by Jeffrey L. Rotman.
Illustrations 2000 by Michael Wertz.
Expert Reader: John McCosker,
Senior Scientist, California Academy of Sciences.
All rights reserved.

Book design by Kelly Tokerud Design .

ISBN 978-1-4521-3400-0

The Library of Congress previously
cataloged this title under ISBN 0-8118-2467-5

Produced by
Swans Island Books

Swans Island Books,
located in Belvedere, California,
has produced imaginative and insightful
illustrated works for adults and children
since 1990. Author and director,
Kristin Joyce, established this book
packaging business with hopes
of enlightening children in natural
sciences and the arts.

This is what people who have come face-to-face with a great white shark remember most.

Scientists and photographers who have met a great white shark admire this awesome animal. But people who only know this shark by reputation fear it. No other animal stirs up emotions like the great white shark. And no other animal has had so much written about it based on so few facts.

Great white sharks are a mystery even to shark scientists because they are so hard to study. They cant be kept in a fish tank for observation. So far, no great white shark has lived more than a few days in an aquarium. Researchers sometimes have to hunt for weeks to find them in the ocean. When the sharks do appear, often lured by the scent of blood, researchers must observe them from inside the safety of a shark cage. Usually, the sharks eat the food hung out to attract them and then disappear into the shadows. Researchers can only guess at what great whites do away from their viewhow far they travel, where they give birth, or how many live in the ocean.

A shark cage is like an underwater elevator enclosed by strong bars on all sides. Floats on the top help the cage stay at the surface in case it gets torn from the steel cables that attach it to the boats deck.
Once when underwater photographers Ron and Valerie Taylor were in a shark cage, a 12-foot (4-meter) great white became tangled in the cable and dragged the cage underwater. The floats kept it from sinking, but they had a wild ride until the shark became tired from struggling to escape. Ron and the boat crew cut it free and the shark swam off.

By counting the growth rings (like tree rings) in cross-sections of shark backbones, scientists have learned that great whites may live 25 to 30 years or longer. Other researchers are tracing the great whites family tree using DNA testing of shark skin samples. They hope to learn whether great whites in one area of the ocean are closely related to those in another area. Although there is much more to learn, what scientists have already discovered about great white sharks may change the way people feel about these monsters of the sea.

Like detectives, ocean biologists are slowly piecing together clues that reveal the true nature of great white sharks. These researchers are learning about how great white sharks survive in the sea, how they behave when theyre hunting or having babies, and what humans need to do to protect them.

Marine biologists attach tags to great white sharks to find out where they go. Each tag has a different number on it, and the researchers record the number and where and when the shark was tagged before releasing the shark. If someone catches the shark again later, the numbered tag lets the scientists know how far the shark has traveled. Some tags have ultrasonic transmitters that allow researchers to track the sharks movements.

Basking shark

Two other kinds of sharks are bigger than the great white. Basking sharks grow to be 40 feet (12 meters) long and whale sharks grow up to 50 feet (15 meters) long; that makes them as long as a school bus. You would think these huge animals eat almost anything, but they actually feed on some of the smallest animals in the sea. Both the basking shark and the whale shark eat small shrimplike creatures called krill, which are no longer than your finger.

Whale shark

From time to time, fishermen in Australia, California, and the Mediterranean have reported catching great white sharks 23 feet (7 meters) long or longer, but scientists doubt these stories. They think maybe the fishermen didnt measure the sharks the way scientists do. But even scientists dont agree on the right way to measure a great white shark. Do you measure from its snout to the tip of its tail? Do you measure to the fork in the middle of the tail? Some measurements dont even include the tail! So how do you know how long a shark really is?