Amazon River Dolphins
Kristin Petrie
DOLPHINS SET II
Amazon River
Dolphins
Kristin Petrie
ABDO Publishing Company
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Published by ABDO Publishing Company, 4940 Viking Drive, Edina, Minnesota 55435.
Copyright © 2006 by Abdo Consulting Group, Inc. International copyrights reserved in all
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Printed in the United States.
Cover Photo: © Gregory Ochoki / SeaPics.com
Interior Photos: © Fernando Trujillo / SeaPics.com pp. 7, 19; © Gregory Ochoki / SeaPics.com
pp. 5, 10, 12, 15, 17; © Todd Pusser / SeaPics.com p. 20-21; Uko Gorter p. 6
Series Coordinator: Megan M. Gunderson
Editors: Megan M. Gunderson, Stephanie Hedlund
Art Direction, Diagram, & Map: Neil Klinepier
Library of Congress Cataloging-in-Publication Data
Petrie, Kristin, 1970Amazon river dolphins / Kristin Petrie.
p. cm. -- (Dolphins. Set II)
ISBN 1-59679-299-X
1. Boto--Juvenile literature. I. Title.
QL737.C436.P48 2005
599.53’8--dc22
2005045795
Contents
AMAZON RIVER DOLPHINS . . . . . . . . . . . 4
SIZE, SHAPE, AND COLOR . . . . . . . . . . . 6
WHERE THEY LIVE . . . . . . . . . . . . . . . . . 8
SENSES . . . . . . . . . . . . . . . . . . . . . . . . . 10
DEFENSE . . . . . . . . . . . . . . . . . . . . . . . 12
FOOD . . . . . . . . . . . . . . . . . . . . . . . . . . 14
BABIES . . . . . . . . . . . . . . . . . . . . . . . . . 16
BEHAVIORS . . . . . . . . . . . . . . . . . . . . . . 18
AMAZON RIVER DOLPHIN FACTS . . . . . 20
GLOSSARY . . . . . . . . . . . . . . . . . . . . . . 22
WEB SITES . . . . . . . . . . . . . . . . . . . . . . 23
INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Amazon River
Dolphins
You may have seen dolphins in a zoo, on television, or
even in the ocean. Many of these dolphins belong to the
Delphinidae family. They are cetaceans that live in the
world’s oceans.
But, there are several dolphin families that you may
not have had a chance to see. Some of these dolphins are
river dolphins. They look different from ocean dolphins,
and they eat different things. They even swim differently!
One river dolphin is the Inia geoffrensis. It is more
commonly known as the Amazon River dolphin. It
belongs to the Iniidae family.
Amazon River dolphins can be friendly creatures, but
they also keep to themselves. They are an important part
of their habitat. And, they are even featured in South
American legends and myths.
4
Amazon River dolphins sometimes act very playful with humans.
They may even retrieve objects or tow a swimmer through the water!
Size, Shape, and
Color
Amazon River dolphins are the largest of the freshwater
dolphins. Males can grow to more than eight feet (2 m)
long. They can weigh up to 350 pounds (160 kg). Females
are generally a little smaller.
Most dolphins have a dorsal fin that sticks out of the
water when they swim near the surface. But, the Amazon
River dolphin has a ridge along its back instead. This
ridge forms a low triangle along the dolphin’s back.
EYE
BLOWHOLE
DORSAL RIDGE
SNOUT
FLIPPER
FLUKE
6
The flippers
and flukes of the
Amazon River
dolphin are large
and broad. Like
other river
dolphins, they
have small eyes
and a long snout.
This long snout
The Tucuxi dolphin also lives in the
holds more than
Amazon River. But Amazon River dolphins,
100 teeth. A
such as these, can be easily identified by
their dorsal ridge and pink coloring.
small head,
bulging melon,
and puffy face complete its distinctive look.
Adult Amazon River dolphins can be shades of gray or
white. Sometimes they become bright pink! This color
change is not completely understood. But, we do know
that age and level of activity are factors. It may be that
capillaries near the skin fill with blood during activity.
7
Where They Live
The Amazon River dolphin is found in South America.
It can be seen in the Amazon River, which is one of the
largest rivers in the world. The large Orinoco River is
also home to this species. In fact, these dolphins live
throughout the Amazon and Orinoco river basins.
Amazon River dolphins prefer to inhabit river
confluences. These are the areas where large rivers
meet. These dolphins are also found where water pools
into floodplains and grasslands. It is in these muddy
waters that Amazon River dolphins make their home.
Small fish, crabs, and other water life are packed into
these areas. In the wet season, the fish spread out into
the flooded forest. The river dolphins do, too! Branches,
rocks, and other debris form obstacle courses for these
dolphins.
8
Arctic
Ocean
NORTH
AMERICA
ASIA
EUROPE
Atlantic
Ocean
Pacific
Ocean
AFRICA
Pacific
Ocean
Indian
Ocean
AUSTRALIA
SOUTH
AMERICA
Atlantic Ocean
Orinoco
River
o
Amaz
Where Amazon River
Dolphins Live
Pacific Ocean
n Riv
er
Senses
Amazon River dolphins need all their senses in this
muddy, tree-lined environment. But, their sense of smell
is not very good. So, they use
their sensitive snouts to probe
for food.
Some river dolphins have
terrible eyesight. But, Amazon
River dolphins can see fairly
well. And, they use a sense that
humans do not have. These
There are more than 1,500
species of fish in the Amazon
dolphins use echolocation.
River. Echolocation helps
Echolocation allows dolphins
dolphins find the food they prefer.
and a few other mammals to
“see” without their eyes! A dolphin makes special noises
that travel into the surrounding water. These noises
bounce off objects and return to the dolphin.
10
The dolphin uses these sounds to create pictures in
its mind. Using echolocation, a dolphin can “see” where
it is and determine where it wants to go. It can also avoid
danger. Most important, the dolphin can find its prey.
Sound wave sent out by dolphin
Echo wave received by dolphin
Defense
Some Amazon River dolphins live alone. Others stay
in small pods of up to 15 dolphins. Except for mating
and mass feeding, they usually keep to themselves.
12
Whether the dolphins are alone or in a pod, their main
enemies are humans! Amazon River dolphins are friendly.
But, it is safer for them if they learn to stay away from
humans. This is a form of defense.
In the past, some of the local people saw the Amazon
River dolphin as sacred. Others did not trust them, so
they avoided them. For both these reasons, the dolphin
remained relatively safe. But as these traditions die out,
the dolphins face more danger from humans.
Large nets used in commercial fishing are one of the
dolphin’s biggest threats. If a dolphin gets caught in a
net, it may die. Another threat is habitat destruction.
The construction of dams blocks dolphins from their usual
habitat. Pollution in the river is also a growing concern.
Opposite page: Some fishers think Amazon River dolphins
are competing with them for the available fish.
Sometimes, the dolphins help herd the fish into the nets.
Other times, they steal the fish for themselves!
13
Food
The Amazon River dolphin’s favorite food is seafood!
These dolphins feast on more than 50 species of fish.
They eat crustaceans, as well as catfish and other small
fish.
Their diet varies depending on the water level and
their habitat. When the water is low, the fish are
crowded into smaller areas. So, Amazon River dolphins
can choose from a wider variety of fish. When the river
basin is flooded, they must search harder for their food.
Another challenge to Amazon River dolphins is seeing
around their large cheeks. To combat this problem, they
sometimes swim upside down to find their next meal.
Once they find food, Amazon River dolphins can use
their teeth to chew. Other dolphins swallow their food
whole. But, the Amazon River dolphin’s back teeth are
like molars. So, they are able to crush and eat the
hard-shelled prey found in the river.
14
The Amazon River dolphin’s mouth is straight, but curves up at the
corners. Their lower and upper jaws can each have 48 to 70 teeth.
15
Babies
Dolphins are mammals. Like humans, dolphins
breathe air. They are warm-blooded and have hair.
They also nurse their young with milk.
A baby dolphin is called a calf. A female Amazon
River dolphin has one calf every four or five years.
Female dolphins are pregnant for 10 to 11 months.
Calves are born between May and July. Typically,
this means they are born when the river water is at its
highest.
Amazon River dolphin calves weigh up to 18 pounds
(8 kg) at birth. Mother and calf stay together for nursing
for more than a year. Amazon River dolphins live for an
average of 30 years.
16
Dolphins are born with hair, but most of them lose it quickly.
However, Amazon River dolphins keep their hair. Scientists
think they use it to enhance their sense of touch.
Behaviors
An interesting feature of the Amazon River dolphin is
its unusual flexibility. Unlike most dolphins, the
Amazon River dolphin has unfused neck vertebrae.
This helps them scan side to side for food. It also allows
them to move freely through crowded, flooded forests.
Another interesting behavior is its slow pace. The
Amazon River dolphin usually swims at about two to
three miles per hour (3 to 5 km/h). But it can swim
quickly, too. And, Amazon River dolphins occasionally
leap above the water surface like other dolphins.
Amazon River dolphins make short dives for one to
four minutes. Then, they must come to the surface to
breathe. Sometimes, they make a loud snort or sneezing
sound when they surface.
Opposite page: The Inia geoffrensis was named
for naturalist Geoffrey St. Hilaire, who was one
of the first scientists to study the species.
18
Amazon River
Dolphin Facts
Scientific Name: Inia geoffrensis
Common Names: Amazon River Dolphin, Pink Dolphin,
Boto, Bufeo, Tonina
Average Size: Males can
grow to more than eight
feet (2 m) long and
more than 350 pounds
(160 kg). Females are
slightly smaller.
Where They’re Found: Amazon and Orinoco river basins
of South America
20
The Amazon River dolphin’s melon is
prominent and changes shape.
Glossary
capillary - a tiny blood vessel.
cetacean (sih-TAY-shuhn) - any of various types of mammal,
such as the dolphin, that live in water like fish.
crustacean (kruhs-TAY-shuhn) - any of a group of animals
with hard shells that live mostly in water. Crabs, lobsters,
and shrimps are all crustaceans.
dorsal - located near or on the back, especially of an animal.
environment - all the surroundings that affect the growth
and well-being of a living thing.
family - a group that scientists use to classify similar plants
or animals. It ranks above a genus and below an order.
flexible - able to bend or move easily.
floodplain - lowlands along a stream or river that frequently
flood.
fluke - either of the fins that make up the tail of a cetacean,
such as a whale or dolphin.
22
habitat - a place where a living thing is naturally found.
melon - the rounded forehead of some cetaceans, which may
aid in echolocation.
molar - a large tooth at the back of the mouth in most
mammals, used for grinding food.
pod - a group of animals, typically whales or dolphins.
pregnant - having one or more babies growing within the
body.
vertebra (VUHR-tuh-bruh) - one of the bones or segments of
cartilage that make up the spinal column.
Web Sites
To learn more about Amazon River dolphins, visit ABDO
Publishing Company on the World Wide Web at
www.abdopub.com. Web sites about these dolphins are
featured on our Book Links page. These links are routinely
monitored and updated to provide the most current
information available.
23
Index
A
Amazon River 8
C
calves 16
character 4, 13
cheeks 7, 14
color 7
D
flippers 7
flooding 8, 14, 16, 18
flukes 7
food 4, 10, 11, 12,
14, 16, 18
N
H
Orinoco River 8
habitat 4, 8, 10, 13,
14, 18
hair 16
head 7
P
defense 11, 13
Delphinidae 4
diving 18
dorsal fin 6
dorsal ridge 6
I
E
life span 16
echolocation 10, 11
eyes 7, 10
M
F
neck 18
O
pods 12, 13
S
senses 10, 11, 14
size 6, 7, 16
snout 7, 10
South America 4, 8
speed 18
Iniidae 4
L
T
mammals 10, 16
mating 12
melon 7
face 7
flexibility 18
24
teeth 7, 14
threats 13