​Tasmania has many species which have become extinct, or are on the verge of extinction, on mainland Australia. Having fewer introduced predators, and a relatively large amount of intact habitat on the island, makes Tasmania a final refuge - a last chance - for many species including the Tasmanian devil.

Tasmanian devil

Endangered (IUCN 3.1)^[1]
Scientific classification

Kingdom: | Animalia
Phylum: | Chordata
Class: | Mammalia
Infraclass: | Marsupialia
Order: | Dasyuromorphia
Family: | Dasyuridae
Genus: | Sarcophilus
Species: | S. harrisii
Binomial name
Sarcophilus harrisii
(Boitard, 1841)^[2]

Distribution of the Tasmanian devil (grey)

The Tasmanian devil (Sarcophilus harrisii) is a carnivorous marsupial of the family Dasyuridae. It was once native to mainland Australia and now found in the wild only on the island state of Tasmania, including tiny east-coast Maria Island where there is a conservation project with disease-free animals.

The size of a small dog, the Tasmanian devil became the largest carnivorous marsupial in the world following the extinction of the thylacine in 1936. It is related to quolls and distantly related to the thylacine. It is characterised by its stocky and muscular build, black fur, pungent odour, extremely loud and disturbing screech, keen sense of smell, and ferocity when feeding. The Tasmanian devil's large head and neck allow it to generate among the strongest bites per unit body mass of any extant mammal land predator,^[3] and it hunts prey and scavenges carrion as well as eating household products if humans are living nearby.

Although it usually is solitary, it sometimes eats with other devils and defecates in a communal location. Unlike most other dasyurids, the devil thermoregulates effectively and is active during the middle of the day without overheating. Despite its rotund appearance, the devil is capable of surprising speed and endurance, and can climb trees and swim across rivers.

It is believed that ancient marsupials migrated from what is now South America to Australia tens of millions of years ago during the time of Gondwana,^[4][5][6] and that they evolved as Australia became more arid. Fossils of species similar to modern devils have been found, but it is not known whether they were ancestors of the contemporary species, or whether the current devils co-existed with these species. The date that the Tasmanian devil became locally extinct from the Australian mainland is unclear; most evidence suggests they had contracted to three relict populations around 3000 years ago. A tooth found in Augusta, Western Australia has been dated to 430 years ago, but archaeologist Oliver Brown disputes this and considers the devil's mainland extinction to have occurred around 3000 years ago.^[7]

This disappearance is usually blamed on dingoes, which are absent from Tasmania. Because they were seen as a threat to livestock and animals that humans hunted for fur in Tasmania, devils were hunted and became endangered. In 1941, the devils, which were originally seen as implacably vicious, became officially protected. Since then, scientists have contended that earlier concerns that the devils were the most significant threat to livestock were overestimated and misplaced.

Devils are not monogamous, and their reproductive process is very robust and competitive. Males fight one another for the females, and then guard their partners to prevent female infidelity. Females can ovulate three times in as many weeks during the mating season, and 80% of two-year-old females are seen to be pregnant during the annual mating season. Females average four breeding seasons in their life and give birth to 20–30 live young after three weeks' gestation. The newborn are pink, lack fur, have indistinct facial features and weigh around 0.20 g (0.0071 oz) at birth. As there are only four nipples in the pouch, competition is fierce and few newborns survive. The young grow rapidly and are ejected from the pouch after around 100 days, weighing roughly 200 g (7.1 oz). The young become independent after around nine months, so the female spends most of her year in activities related to birth and rearing.

Since the late 1990s, the devil facial tumour disease (DFTD) has drastically reduced the devil population and now threatens the survival of the species, which in 2008 was declared to be endangered. Programs are currently being undertaken by the Government of Tasmania to reduce the impact of the disease, including an initiative to build up a group of healthy devils in captivity, isolated from the disease. While the thylacine was extant it preyed on the devil, which targeted young and unattended thylacine cubs in their dens. Localised populations of devils have also been severely reduced by collisions with motor vehicles, particularly when they are eating roadkill.

The devil is an iconic symbol of Tasmania and many organisations, groups and products associated with the state use the animal in their logos. It is seen as an important attractor of tourists to Tasmania and has come to worldwide attention through the Looney Tunes character of the same name. Starting in 2013, Tasmanian devils are again being sent to zoos around the world as part of the Australian government's Save the Tasmanian Devil Program

By CARL ZIMMER

Published: January 21, 2013

In November, a team of biologists journeyed to Maria Island, three miles off the Australian island state of Tasmania, taking with them 15 plastic cylinders. They loaded the cylinders into S.U.V.’s, drove them to an abandoned farm and scattered them in the fields.

Simon de Salis/Department of Primary Industries, Parks, Water and Environment

A young disease-free devil emerged from a tube to its new home on Maria Island.

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Before long 15 Tasmanian devils emerged from the containers, becoming the first ever to inhabit the island.

“All indications are that they’re doing very well,” Phil Wise, a government wildlife biologist who leads the project, said of the devils — fierce-looking, doglike marsupials that have become an endangered species on the much larger island for which they are named.

This spring the team plans to take more devils to Maria (pronounced ma-RYE-uh). The goal is to establish a healthy colony that will endure for decades to come. The stakes of the project are high: the survival of the entire species may depend on it.

Many species are threatened with extinction, but the Tasmanian devil faces a singular enemy: an epidemic of cancer. A type of facial tumor has in effect evolved into a parasite, with the ability to spread quickly from one devil to another, killing its victims in a few months.

“We have very little time to save the species,” said Katherine Belov, a biologist at the University of Sydney.

An international network of biologists has spent the past decade figuring out this new kind of disease. “It’s been quite a struggle just to learn some of the basics,” said Elizabeth Murchison, of the University of Cambridge in England.

But recently Dr. Murchison and other experts have gained important insights into how the cancer evolved into a parasite. Some scientists are now trying to translate that knowledge into a treatment, perhaps a cancer vaccine.

There is no guarantee that these projects will save the devils, so Mr. Wise and his colleagues are setting up a drastic Plan B: they are establishing Maria Island as a cancer-free refuge for wild Tasmanian devils.

Then, if the devils die out in Tasmania, Dr. Belov said, “the disease will be gone from the mainland, and then they can be introduced back in the wild.”

Biologists first encountered the cancer in the late 1990s. The tumors grew on the devils’ faces or inside their mouths, and within six months the animals were dead. The first cases appeared in eastern Tasmania, and with each passing year the cancer’s range expanded westward.

When scientists examined the cells in the tumors, they got a baffling surprise. The DNA from each tumor did not match the Tasmanian devil on which it grew. Instead, it matched the tumors on other devils. That meant that the cancer was contagious, spreading from one animal to another.

There are only a few reports of humans developing cancer from other people’s tumors hidden in transplanted skin or other organs. Only one other example of contagious cancer is known from the natural world, a tumor in dogs.

Dr. Murchison led a team of researchers who sequenced the entire genome of two tumor cells. They published the sequences last February, and since then they have launched a project to sequence hundreds more genomes of Tasmanian devil facial tumors.

Their studies and others like them are revealing how the Tasmanian cancer got its start. It probably originated in the 1980s or early 1990s in a single animal, most likely a female. A nerve cell in her face underwent a drastic mutation: its chromosomes shattered and then stitched themselves back together.

“The cell was still able to function, because there wasn’t too much DNA lost,” Dr. Belov said. “It’s a bit of a freak of nature.”

The cancer then spread to other devils by taking advantage of their behavior. The animals frequently fight, biting their opponents’ faces. During these battles, Tasmanian devils sometimes bite off bits of a tumor. The cells slip into the attacker’s own bloodstream and travel to its face. There they grow a new tumor.

Dr. Murchison and her colleagues have identified some 20,000 mutations in the tumors that are not found in normal Tasmanian devil DNA. But they do not know which of those mutations originally gave rise to the cancer.

Recent research is revealing that the cancer has been evolving. “Up until a year ago we thought the tumor was completely stable,” Dr. Belov said. “But now we know that’s not the case.”

She and her colleagues recently examined cancer cells collected from Tasmanian devils in 2007 and 2008, comparing them with cells collected from 2010 to 2012. They surveyed molecular caps that cover some genes, known as methylation marks. These marks can keep genes from producing proteins.

In the Jan. 7 issue of Proceedings of the Royal Society B, Dr. Belov and her colleagues reported that recent cancers have fewer methylation marks than older ones, suggesting that the cancer cells are unmuzzling genes and using their proteins to spread more efficiently. The cancer, she and her colleagues wrote, “should not be treated as a static entity, but rather as an evolving parasite.”

Until recently, most scientists believed Tasmanian devils were uniquely vulnerable to contagious cancers. They have very little genetic diversity, and so they might not be able to recognize a tumor as foreign.

But if that were the case, their immune systems would not reject tissue from other devils. In fact, however, when devils were given skin grafts, “they all rejected really nicely,” said Alexandre Kreiss, a research fellow at the Menzies Research Institute in Tasmania. “So we knew then there was something else to the tumor.”

Instead, it turns out, the cancer cells camouflage themselves. They have stopped making a molecular identity badge that mammal cells normally produce.

All of the scientists studying the tumors know that they cannot afford to dawdle. The cancer has already wiped out 84 percent of the Tasmanian devil population and shows little sign of slowing. “You feel that the clock is always ticking,” Dr. Murchison said.

But she sees some reasons for hope. In the far northwest corner of Tasmania, for example, a population of devils shows signs of resisting the cancer. Some of the animals appear to have destroyed their tumors. As a result, only about 20 percent of the devils there have died.

If the devils do not escape the cancer on their own, scientists may be able to help them. “I think the potential for a vaccine is pretty good if we can understand what is going on there,” Dr. Murchison said.

But Dr. Kreiss warns that with 35,000 devils left in the wild, no vaccine can be a panacea. “Even if we had a perfect vaccine, we’d probably have to vaccinate every animal more than once,” he said. “I don’t see us doing that for the whole population.”

In case no medicine works, the federal and Tasmanian governments are quarantining a so-called “insurance population” of devils. The program now has 500 cancer-free Tasmanian devils in zoos and sanctuaries. It is to ensure they do not become too tame to survive on their own that Mr. Wise and his colleagues are establishing the wild population on Maria Island.

While Tasmanian devils are the first species known to be threatened by a contagious cancer, they may not be the last. “It’s quite likely that there are more out there that haven’t been identified,” Dr. Murchison said. “It might have led to the extinction of other species.”

This article has been revised to reflect the following correction:

An article on Tuesday about an effort to save Tasmanian devils from an epidemic of cancer referred incorrectly to a contagious cancer in dogs. Canine transmissible venereal tumor can be malignant, it is not benign. (But unlike the Tasmanian devil cancer, it is not causing a lethal epidemic in dogs