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Hope for the devil? The race is on to save a rare animal from a deadly disease.

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Something strange was up on Australia's island of Tasmania, and it wasn't the unearthly screeches in the night. Zoologist Menna Jones was used to hearing those---the sounds of the Tasmanian devil. The problem was the horrific lumps that bulged from the devils' faces and necks, preventing the animals from eating and drinking--thereby ensuring a slow, painful death.

A photographer had spotted a devil with facial tumors in 1996, and Jones, who works at the University of Tasmania, had encountered another in 1999. But no one suspected that a deadly disease was spreading rampantly until stricken devils began dying across Jones's study site in 2001. "That was the first indication that we had a devastating disease in our midst," she says.

By the start of this year, the mysterious malady--devil facial tumor disease (DFTD)--had wiped out 90 percent of the Tasmanian devil population (see Widespread Disease, right). With no cure in sight, researchers warn that the remaining 20,000 to 30,000 devils could disappear within a decade. As some scientists strive to uncover clues about the deadly disease, other experts have launched captive-breeding programs like Devil Ark--a newly opened sanctuary designed to save the species from extinction.

A DEVIL OF A DISEASE

Tasmanian devils--which got their name from their screeches, snarls, and growls--are small creatures with mighty big attitudes. The cat-size animals, which are found in the wild only in Tasmania, are an unusual combination: They're carnivorous marsupials--meat eaters whose babies finish developing inside their mothers' pouches. But the disease afflicting them--a contagious cancer--is even more unusual.

Normally, cancer isn't contagious. It arises from a creature's own cells. When a cell divides, it makes a copy of its DNA, or genetic material, which contains the instructions that cells need to function. But when the copy contains an error, this mutation, or change to the genetic code, gives faulty instructions. A cancer mutation instructs a cell to divide out of control, forming a tumor. Tumor cells then metastasize, or spread to other areas of the body.

If tumor cells enter another animal, that animal's immune system usually recognizes and eliminates the intruders. But a devil can't tell another devil's cells from its own.

"They're all genetically very similar, almost like identical twins," says Kathy Belov, a geneticist at the University of Sydney in Australia. That's because sometime in the past, their population crashed and rebounded from just a few animals. The result: Cancer cells from one devil can survive in others (see How the Devil's Cancer Catches, below).

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But DFTD doesn't spread only because of look-alike cells. It also needs "a very intimate method of transfer, because tumor cells are like body cells; they desiccate (dry out) very quickly," says Jones, "so they won't live for very long outside the host." The devils' crankiness helps with that. When a healthy devil bites one infected with DFTD, tumor cells can enter the healthy animal through small cuts or sores in its mouth. The previously healthy animal is now doomed to die within a few months.

Recently, researchers have found a glimmer of hope. Devils in northwestern Tasmania have a slightly different genetic makeup, and the disease is spreading more slowly among them. "We're hopeful that some of these animals might be able to mount an immune response to the disease," says Belov. But it's too soon to tell. If the devils can't fight off the disease, scientists expect them to become extinct in the wild. DFTD would disappear with them.

THE DEVILS' INSURANCE

Fortunately, experts have a backup plan. They're breeding hundreds of healthy devils in Australian zoo pens. "In the case of extinction in the wild, we could reintroduce the species," says Jones. The released devils would be safe from the extinct disease.

But the captive devils may be making themselves too much at home. According to Tim Faulkner, operations manager of the Australian Reptile Park, in those small pens, the devils lose a lot of their wild behaviors. For instance, they stop being nocturnal and stay up during the day, when the zoo is busy. When the time comes for release--especially if it's several generations down the road--will the animals know how to act in the wild?

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To ensure that they will, the Australian Reptile Park built Devil Ark. This sanctuary has huge, free-range enclosures in the mountains of mainland Australia. One advantage of the location: Because devils disappeared from mainland Australia 500 years ago, DFTD doesn't exist there. Another perk: The high-elevation bushland is similar to the devils' natural habitat in Tasmania. "It's devil heaven," says Faulkner.

In January 2011, Devil Ark opened with 40 devils. "They instantly [returned] to their normal behaviors and their wild preferences," reports Faulkner. The devils snubbed human-built nest boxes in favor of natural burrows, and they switched to a nocturnal schedule. The staff watches the animals with cameras and remote sensors and can intervene if a devil runs into trouble. They hope to expand the sanctuary to hold 1,500 devils.

The first night after researchers released the healthy devils into Devil Ark, Faulkner heard screeches. "It's a beautiful sound," he says.

WIDESPREAD DISEASE

The first report of devil facial tumor disease came in 1996 from the northeastern tip of Tasmania. By what year had the disease spread to near the West Pencil Pine study site?

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HOW THE DEVIL'S CANCER CATCHES

A single devil is to blame for the devil facial tumor disease (DFTD) that began spreading among devils 15 years ago. Cancer normally isn't contagious, but unusual circumstances have enabled the cancer to jump among devils.

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[1] A Tasmanian devil has DFTD, a cancerous tumor on its face.

[2] While fighting or mating, a healey devil bites one sickened with DFTD. Cancer cells enter the healthy devil's body.

[3] Immune-system cells usually launch an assault against disease-causing pathogens. But because devils are genetically similar, the animal's immune system does not recognize the tumor cells as intruders. It does nothing to attack them and they divide uncontrollably.

[4] Unstopped, the cancer cells divide and t form a facial tumor. The cancer is ready to spread to the next unlucky devil.

HANDS-ON SCIENCE

TRACK A DISEASE

PREDICT [right arrow] How does immunity affect the spread of disease in a population?

MATERIALS [right arrow] envelopes from your teacher * * clock

PROCEDURE [right arrow]

1 Your teacher will hand out envelopes, each containing a strip of paper, to the class. Check your envelope without letting anyone see what's inside. If the envelope contains red paper, you are a Tasmanian devil that's "infected" with devil facial tumor disease. White paper means you are a healthy devil.

2 Circulate among your classmates for 60 seconds, then freeze.

3 Whisper the color of your paper to the person closest to you. If you hear "white" from your neighbor, you stay your original color. If you hear "red," you are now infected. You must whisper "red" from now on, no matter what color is whispered to you.

4 Repeat steps 2 and 3 two more times. At the end of the round, tally the number of "infected devils."

5 Repeat steps 1 to 4 with new envelopes from your teacher. This time, some envelopes contain green paper. If your paper is green, you are "immune" and remain green no matter what color is whispered to you. Immunity can't be passed on, so if you hear "green," ignore it and stick to your original color.

CONCLUSIONS [right arrow] How did the presence of immunity (green paper) affect the spread of the disease?

* Teachers: See Teacher's Edition (page TE2) for background information.

LESSON PLANS

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STANDARDS

NATIONAL SCIENCE EDUCATION STANDARDS:

Grades 5-8: Populations and ecosystems

Grades 9-12: Behavior of organisms

COMMON CORE STATE STANDARD: LITERACY IN SCIENCE:

9. Compare and contrast information from experiments, videos, simulations, and other sources

OBJECTIVE

To understand how cancer acts inside the body, and how devil facial tumor disease is unusual among cancers.

BEFORE READING

* What is cancer? Does it occur in animals besides humans? (Cancer is a disease in which abnormal cells divide out of control. Animals besides humans do get cancer.)

* What is a tumor? (A tumor is a mass of abnormal tissue somewhere in the body that may be malignant or infectious.)

* Is cancer usually contagious? (No.)

LESSON

1. Ask your students the before-reading questions. Record their answers on the board. Engage them in a discussion about cancers in humans versus cancers in animals.

2. Go online to www.scholastic.com/scienceworld. Open the digital edition to pp. 8-9, and have students do the same in their magazines. Call on a volunteer to read the headline, the text immediately under the headline, and the first paragraph.

(c) 3. Flip to page 10 and, using the mask tool, block everything but the picture of an infected devil. Ask students to analyze the photo and make observations about this deadly disease.

(d) 4. Discuss students' impressions of the disease. Ask them how they think it might be different from other cancers, and record any findings in a digital sticky note.

5. Read the rest of the article together, allowing student volunteers to read paragraphs aloud.

DISCUSSION

Perform the hands-on experiment on page 11. Discuss the results. How did the disease spread? What would happen if you were to repeat the experiment with more "infected" students?

ASSESSMENT

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Use the skills sheet entitled "A Devilish Disease" from the online database at www.scholastic.com/scienceworld to reinforce the sequence of devil facial tumor disease infection.

DON'T TEACH BIOLOGY?

Go to www.scholastic.com/scienceworld to download these assessment skills sheets instead:

EARTH SCIENCE: THE DEVIL'S HOME

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Thousands of years ago, Tasmania was connected to Australia. Read the passage to learn more about how Tasmania separated from the mainland and how this separation led to a habitat full of creatures found only on Tasmania.

PHYSICS: CARNIVORE COMPARISON

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Tasmanian devils are known to be aggressive creatures. Unfortunately, this characteristic has helped spread the devastating cancer through bites. Use this graphing activity to learn more f about how the force o a devil s bite compares with that of other carnivorous mammals.

TEACHER INSTRUCTIONS FOR THE HANDS-ON:

Use these instructions to prepare for the hands-on activity on page 11 of the student edition:

For Round 1: Place a strip of red paper inside two of the envelopes. Put white strips in the rest.

For Round 2: Keep the two envelopes with red strips, and replace four of the white strips with green strips of paper. The green strips will represent immunity.

RESOURCES

* VIDEO EXTRA: Watch a video that shows researchers releasing healthy devils into Devil Ark at: www.scholastic.com/scienceworld.

* Check out the Tasmania Parks and Wildlife Service's Web site to learn more about the Tasmanian devil and other animals that live on this island: www.parks.tas.gov.au/

DIGITAL ISSUE KEY:

(a) SHOW ALL PAGES

(b) HOME

(c) MASK TOOL

(d) DIGITAL STICKY NOTES

(e) TEXT HIGHLIGHTER

(f) DRAWING TOOL

(g) GAME

(h) POP-UP

(i) VIDEO PLAYER

HANDS-ON ACTIVITY

NAME:--

TRACK A DISEASE

In "Hope for the Devil?" (p. 8), you read about how a contagious cancer is threatening the survival of Tasmanian devils. Scientists have found a group of devils that may actually become immune to the disease--and slow the spread. How does immunity affect
MATERIALS:

envelopes from your teacher* * clock

* Teachers: See page TE2 for details.

PROCEDURE:

1. Your teacher will hand out envelopes, each containing a strip of
paper, to the class. Check your envelope without letting anyone see
what's inside. If the envelope contains red paper, you are a
Tasmanian devil that's "infected" with devil facial tumor disease.
White paper means you are a healthy devil.

2. Circulate among your classmates for 60 seconds, then freeze.

3. Whisper the color of your paper to the person closest to you. If
you hear "white" from your neighbor, you stay your original color.
If you hear "red," you are now infected. You must whisper "red"
from now on, no matter what color is whispered to you.

4. Repeat steps 2 and 3 two more times. At the end of the round,
tally the number of "infected devils" and enter the number next to
"Round 1" in the data table on the right.

5. Repeat steps 1 to 4 with new envelopes from your teacher. This
round, some envelopes contain green paper. If your paper is green,
you are "immune" and remain green no matter what color is whispered
to you. Immunity can't be passed on, so if you hear "green," ignore
it and stick to your original color. This time, record your data
next to "Round 2."


CONCLUSIONS:

1. How did the presence of immunity (green paper) affect the spread of the disease?
DATA TABLE

Round Number
 Infected

Round 1

Round 2


ANWERS

1. Having immune devils in the mix slowed the spread of the disease.
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Article Details
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Title Annotation:BIOLOGY: CANCER; Tasmanian devil
Author:Adams, Jacqueline
Publication:Science World
Geographic Code:8AUST
Date:Sep 26, 2011
Words:2157
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