Non-fiction: Gentle Giants
Gentle Giants
By Stephen Fraser
Would you stick your head into the mouth of a shark as big as a
whale?
Several years ago, Robert Hueter found himself with his head all the way
inside a shark’s mouth. The fish was about 22 feet long and weighed more
than 3,000 pounds. “I put my whole head and shoulders into it,” he says.
Hueter is a biologist at the Mote Marine Laboratory in Sarasota, Fla. He and
a colleague, Phil Motta, of the University of South Florida, were conducting
research at the Georgia Aquarium. The big shark had been safely
anesthetized—put in a sleeplike state. “At no time did we feel we were in
any danger,” says Hueter. “It was more of a feeling of ‘Let’s not hurt the
shark; let’s be very careful.’
Mote Marine
Laboratory
“Afterwards, Phil said to me, ‘Boy, we sure do some crazy things together!’”
The animal that the two men examined was a juvenile whale shark, the
biggest species of fish in the world. An adult whale shark can weigh 14 tons
and be 14 meters (45 feet) long. Despite their size and abundance, whale
sharks are a mystery in many ways.
Filter Feeders
Hueter saw his first whale shark when he was a college student. “I was
amazed at its size and power when it swam,” he recalls. “But I wasn’t
frightened, because the animal was so gentle.”
1
© 2012 ReadWorks®, Inc. All rights reserved.
Article: Copyright © 2009 Weekly Reader Corporation. All rights reserved.
Weekly Reader is a registered trademark of Weekly Reader Corporation.
Used by permission.
Thomas Bolster
Wednesday, March 27, 2013 1:39:06 PM ET
40:6c:8f:28:98:23
Non-fiction: Gentle Giants
Gentle isn’t a word you would expect to see in an article about sharks,
especially giant ones. Sharks have fearsome reputations. But though they’re
carnivores (flesh eaters), sharks rarely attack people. “There are only a
dozen or so species that have ever bitten a human,” says Hueter, “and none
of them actively hunt humans as prey.”
The whale shark got its name because it’s as big as some whales. And, like
many whales, it’s a filter feeder, an animal that strains food from the water
it swallows. The food that whale sharks filter is mainly zooplankton (tiny
marine animals and fish eggs). “We actually call whale sharks planktivorous,
which means ‘plankton-eating,’” says Hueter.
A whale shark eats on the run. As it cruises through the ocean, water flows
continuously into its mouth. Filter pads in its throat strain out the
zooplankton, and the filtered water is expelled through the shark’s gills. The
trapped food gathers in a big ball at the back of the animal’s throat before
being swallowed.
Filter feeding mechanisms are what Hueter and Motta were studying when
they stuck their heads inside the whale shark at the Georgia Aquarium. “We
used a waterproof camera and photographed the inside of the animal’s
mouth,” says Motta. “We were trying to figure out how the animal could gulp
so much zooplankton without clogging its gills. We still are not sure.”
Rasp Teeth
Although whale sharks don’t bite or chew, they have thousands of tiny teeth,
each the size of a match tip, arranged in hundreds of rows. The rows
resemble rasps—woodworking tools that have tiny bumps arranged along a
metal blade. The whale shark’s Latin name, Rhincodon typus, means “rasp
tooth type.” Hueter believes the teeth are vestigial, an evolutionary leftover
from the whale shark’s ancestor.
That ancestor was probably a creature similar to today’s nurse shark, a 135kilogram (300-pound) species that often rests on the seabed and feeds on
fish and other marine animals there. Hueter guesses that the whale shark’s
ancestor originally ate fish eggs but eventually took advantage of the
nutritional benefits of zooplankton in the open sea.
2
© 2012 ReadWorks®, Inc. All rights reserved.
Article: Copyright © 2009 Weekly Reader Corporation. All rights reserved.
Weekly Reader is a registered trademark of Weekly Reader Corporation.
Used by permission.
Thomas Bolster
Wednesday, March 27, 2013 1:39:06 PM ET
40:6c:8f:28:98:23
Non-fiction: Gentle Giants
Shawn Heinrichs; Bob
Cranston/Animals Animals
Left: A whale shark and biologist
Robert Hueter (inset) Above: A
tourist swims with a whale shark.
Whale shark tourism is a
multimillion-dollar industry
around the world.
Zooplankton can be so abundant in the whale shark’s feeding grounds, adds
Motta, that visibility in the water is limited to 3 to 4.5 meters (10 to 15
feet). “When a whale shark suddenly appears ahead, it’s like confronting a
school bus underwater,” he says.
Shutterstock
A head-on view of a
whale shark’s open
mouth
Whale sharks are also distinctive for being aplacentally viviparous. Their
pups hatch from eggs inside the mother’s body and continue to develop
there, feeding on yolk and nutritional liquid, until they are born alive. By
contrast, some sharks have a placenta, an organ that provides oxygen and
nourishment to the pups inside the mother’s body. Other, less advanced
3
© 2012 ReadWorks®, Inc. All rights reserved.
Article: Copyright © 2009 Weekly Reader Corporation. All rights reserved.
Weekly Reader is a registered trademark of Weekly Reader Corporation.
Used by permission.
Thomas Bolster
Wednesday, March 27, 2013 1:39:06 PM ET
40:6c:8f:28:98:23
Non-fiction: Gentle Giants
shark species lay eggs on the ocean floor, and the fetuses develop for weeks
before hatching.
Shutterstock
Gill slits on the flank of a
whale shark’s body
“There is no parental care in any shark species,” says Hueter. “The offspring
are strictly on their own after they are born.”
Mystery List
Hundreds of thousands of whale sharks are thought to populate the oceans
in a band of tropical waters that circles the globe. In 2007, Hueter and his
colleagues attached a tracking device to an adult whale shark that they had
named Rio Lady. In 150 days, she traveled nearly 8,000 kilometers (5,000
miles) from Mexico’s Yucatán Peninsula southeast to a point halfway
between Brazil and Africa. Hueter suspects that whale sharks give birth
there.
Shutterstock
The largest known whale
sharks are roughly the length
of a school bus.
4
© 2012 ReadWorks®, Inc. All rights reserved.
Article: Copyright © 2009 Weekly Reader Corporation. All rights reserved.
Weekly Reader is a registered trademark of Weekly Reader Corporation.
Used by permission.
Thomas Bolster
Wednesday, March 27, 2013 1:39:06 PM ET
40:6c:8f:28:98:23
Non-fiction: Gentle Giants
That’s one mystery among many that scientists are investigating. “Whale
sharks dive deeper than a mile,” adds Hueter. “We don’t know why they do
that, or where they mate, or how long they live. And then there’s the
question of how they ingest so much zooplankton without clogging their gills.
The list goes on.”
5
© 2012 ReadWorks®, Inc. All rights reserved.
Article: Copyright © 2009 Weekly Reader Corporation. All rights reserved.
Weekly Reader is a registered trademark of Weekly Reader Corporation.
Used by permission.
Thomas Bolster
Wednesday, March 27, 2013 1:39:06 PM ET
40:6c:8f:28:98:23
!
!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$%&'()%*!+$)&,$!+'-)&%!!
Name:
Date: _______________________
1. What do whale sharks mostly eat?
A
B
C
D
large fish
turtles
smaller sharks
zooplankton
2. How does the author describe whale sharks?
A
B
C
D
as
as
as
as
dangerous to humans
powerful but gentle
large and violent
biting machines
3. After reading the passage, you can conclude all of the following about Robert Hueter
EXCEPT
A
B
C
D
he
he
he
he
is comfortable around whale sharks
is afraid of some flesh-eating sharks
enjoys working with other biologists
finds his job to be interesting
4. Read this sentence from the passage: “Zooplankton can be so abundant in the whale
shark’s feeding grounds, adds Motta, that visibility in the water is limited to 3 to 4.5
meters (10 to 15 feet).”
In this sentence, the word abundant means
A
B
C
D
having impaired vision
frightening to watch
difficult to get ahold of
existing in large amounts
5. Why does the author include the last paragraph (“That’s one mystery…”) in the
passage?
A
B
C
D
to
to
to
to
describe how little is known about whale sharks
explain why whale sharks are so fascinating
persuade other scientists to study whale sharks
describe how whale sharks eat so much food
1
®
© 2012 ReadWorks , Inc. All rights reserved.
Thomas Bolster
Wednesday, March 27, 2013 1:39:06 PM ET
40:6c:8f:28:98:23
!
!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$%&'()%*!+$)&,$!+'-)&%!!
6. How did the whale shark get its name?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
7. Robert Hueter said, “When a whale shark suddenly appears ahead, it’s like confronting
a school bus underwater.” What might he have meant by that? How do you know?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
8. The question below is an incomplete sentence. Choose the word that best completes
the sentence.
Sharks have fearsome reputations, ________ they rarely attack people.
A
B
C
D
or
and
but
because
2
®
© 2012 ReadWorks , Inc. All rights reserved.
Thomas Bolster
Wednesday, March 27, 2013 1:39:06 PM ET
40:6c:8f:28:98:23
!
!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"#$%&'()%*!+$)&,$!+'-)&%!!
9. Answer the following questions based on the sentence below.
Several years ago, Robert Hueter stuck his head inside a whale shark’s mouth to
photograph the inside of the animal’s mouth.
Who? _________________________________________________________________
(did) What? stuck his head inside a whale shark’s mouth
Why? _________________________________________________________________
When? ________________________________________________________________
10. Vocabulary Word: carnivores: meat eaters.
Use the vocabulary word in a sentence: ______________________________________
______________________________________________________________________
______________________________________________________________________
3
®
© 2012 ReadWorks , Inc. All rights reserved.
Thomas Bolster
Wednesday, March 27, 2013 1:39:06 PM ET
40:6c:8f:28:98:23