Tasmanian Devils
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- For the cartoon character, see The Tasmanian Devil.
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| Sarcophilus laniarius (Owen, 1838) Template:Taxobox begin synonyms Template:Taxobox synonym entry simple Template:Taxobox end synonyms |
The Tasmanian Devil (Sarcophilus laniarius) is a carnivorous marsupial found exclusively on the island of Tasmania, and is the largest carnivorous marsupial in the world. The size of a small dog but stocky and muscular, the Tasmanian Devil is characterised by its black fur, offensive odour when stressed, extremely loud and disturbing screeching and vicious temperament when feeding.
The Tasmanian Devil was hunted by humans until 1941 when it was officially protected. The Tasmanian Devil is currently threatened by an outbreak of Devil Facial Tumor Disease which has reduced the devil population by up to 50%.
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Taxonomy
The Tasmanian Devil was first described by G. P. Harris in Tasmania in 1807, he named it Didelphis ursinaTemplate:Mn. The devil was later renamed Dasyurus laniarius by Richard Owen in 1838. In 1841 it was shifted to the genus Sarcophilus and named ??Sarcophilus harisii by Pierre Boitard, the name meaning Harris' meat lover. A revision of the devils taxonomy resulted in a change of the species name to Sarcophilus laniarius in the 1980s Template:Mn, although the name S. harrisii is still in wide use.
The Tasmanian Devil is the only member of the genus Sarcophilis. They are most closely related to quolls and more distantly to the ThylacineTemplate:Mn.
Physical description
The Tasmanian Devil is the largest surviving carnivorous marsupial in Australia. It has a squat and thickset build, with a large head and a short stubby tail. Unusually for a marsupial, the forelegs are a little longer than the hind legs. The fur is usually black; irregular white patches on the chest and rump are common. Males are usually larger than females, weighing up to 12 kg (though 7 to 9 kg is more typical), and stand 30 cm at the shoulder. Analysis of mammalian bite force corrected for body size showed that the Tasmanian Devil has the strongest bite of any living mammalTemplate:Mn. The power of the jaw is in part due to the devils comparatively large head. Tasmanian devils have one set of teeth that continue to grow slowly throughout their lifeTemplate:Mn.
Tasmanian Devils have long whiskers on their face and in clumps on the top of the head. The whiskers help the devil locate prey when it is foraging in the dark, and aid in detecting the closeness of other devils during feeding. Hearing is their dominant sense, and they also have an excellent sense of smell. Their vision is black and white which means that they can detect a moving object but if it is stationary they will have difficulty in seeing itTemplate:Mn. They produce a strong odour when stressed.
Reproduction
Mating takes place in March in sheltered locations, devils are not monogamous and the female will mate with several males if she is not guarded after mating. Gestation lasts 31 days, and then devils give birth to 20-30 young each weighing approximately 0.18 to 0.24 gramsTemplate:Mn; however the female has only 4 nipples, so a maximum of four young will survive. The young are carried in a pouch which, like that of the wombat, opens to the rear. They leave the pouch four and a half months after they were born as fully formed but small copies of the parent weighing about 200 grams, and they remain in the den for another three months or so, first starting to venture outside between October and December before becoming independent in January. Females breed when they reach sexual maturity, probably in their second yearTemplate:Mn. The average life span of a Tasmanian Devil is 6 yearsTemplate:Mn.
Ecology and behaviour
Tasmanian Devils are widespread throughout Tasmania and fairly common, particularly in dry sclerophyll forest and coastal woodland with open patches. The Tasmanian Devil is a nocturnal and crepuscular hunter, spending the days in dense bush or in a hole. Young devils can climb trees, but tree climbing becomes more difficult as they grow; devils can also swim. They are predominately solitary animals and do not form packsTemplate:Mn. They occupy territories of 8 to 20 km² which overlap considerably.
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The Tasmanian Devil can take prey up to the size of a small wallaby, but in practice it is opportunistic and eats carrion more often than it hunts for live prey. Its favourite food is wombat, but it will eat all small native mammals, domestic mammals like sheep, birds, fish, insects, frogs and reptiles, diet is largely varied depending on the food availableTemplate:Mn. They eat 15% of their body weight a day, and can eat up to 40% of their body weight in 30 minutes if the opportunity arisesTemplate:Mn. Tasmanian Devils will eliminate all traces of a carcass as they devour all bones and fur in addition to the meat and internal organs of a carcass. This has earned them the gratitude of Tasmanian farmers, as the speed at which they will clean a carcass helps prevent the spread of insects that might otherwise harm livestock.
Eating is a social event for the Tasmanian Devil and much of the noise they produce is the result of up to 12 animals gathering at a carcass, when their noisy communal eating can often be heard several kilometres away. Twenty physical postures including their characteristic vicious yawn, and 11 different vocal sounds have been identified in when feeding devils communicate, usually establish dominance by sound and physical posturing, although fighting does occurTemplate:Mn. Adult males are the most aggressive and scaring from fighting over food and mates is common.
Status
Tasmania was for some time the last refuge of large marsupial carnivores. All the larger carnivorous marsupials became extinct in mainland Australia shortly after humans arrived. Only the smallest and most adaptable survived. Fossil evidence shows that Tasmanian Devils retained a place until around 600 years ago (about 400 years before European colonisation). Their extinction is attributed to predation by Dingoes and hunting by Indigenous AustraliansTemplate:Mn. In Dingo-free Tasmania, marsupial carnivores were still active until Europeans arrived. The extermination of the Thylacine is well known; it is less well-known that the Tasmanian Devil was also threatened.
The first Tasmanian settlers ate Tasmanian Devil, and it is reported to have tasted like vealTemplate:Mn. A bounty scheme was introduced as early as 1830 to remove the devil from rural properties as it was believed the devils would hunt and kill livestockTemplate:Mn. Over the next hundred years, trapping and poisoning brought them to the brink of extinction. Even after the death of the last Thylacine, action was slow in coming, but eventually, in 1941, they were protected by law, and the population has slowly recovered. Tasmania and Australia prohibit the export of Tasmanian Devils and there are currently no animals outside Australia. The last known overseas devil died in California in 2004.
Devil Facial Tumor Disease
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First seen in 1999, Devil Facial Tumor Disease (DFTD) has ravaged Tasmania's wild devils, and estimates of the impact range from 20% to as much as a 50% decline in the devil population with over 65% of the State affectedTemplate:MnTemplate:Mn. High-density populations of Tasmanina Devils that are affected with the disease suffer up to 100% mortality of resident devils in 12-18 monthsTemplate:Mn. The disease has mainly been concentrated in the state?s eastern half, although in early 2005, 3 cases were confirmed in South Tasmania.
DFTD begins as lesions and lumps around a devil's mouth. The lesions and lumps develop into cancerous tumours that spread from the face to the entire body. The tumours interfere with feeding and the Devil may starve to death. The cancer has been identified as a neuroendocrine cancer, and all cancer cells have identical chromosomal rearrangementsTemplate:Mn. A virus was initially thought to cause DFTD, but no evidence for a virus could be detected in cancer cells. The cancer cells themselves are being investigated as the infective agent, consistent with transmission of the cancer by biting. The DFTD cells have a similar karotype to cancer cells from Canine transmissible venereal tumor a contact transmissible cancer of dogsTemplate:Mn.
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Tasmanian Devil populations are being monitored in the field to track the spread of the disease. Two insurance populations of disease-free devils are being established at an urban facility in the Hobart suburb of Taroona and at Maria Island off the east coast of Tasmania. Captive breeding in mainland zoos is also a possibility. In May 2005 a recommendation was made to include the Devil on the Tasmanian Threatened Species list as a vunerable species, which means that it is at risk of extinction in the medium termTemplate:Mn.
Decline in Devil numbers in also seen as an ecological problem since the presence of the Tasmanian Devil in the Tasmanian forest ecosystem is believed to have prevented the establishment of the Red Fox which was illegally introduced to Tasmania in 2001Template:MnTemplate:Mn. Foxes are a problematic invasive species in all other states of Australia. If foxes became established in Tasmania they would also hinder the recovery of the Tasmanian Devil.
Cultural impact
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The Tasmanian Devil is an iconic animal within Australia. The Tasmanian Devil is the symbol of the Tasmanian National Parks and Wildlife Service, and the Tasmanian Australian Rules Football team is known as the devils. The Devil was one of six Australian native animals to appear on Australian two hundred dollar coins issued between 1989 and 1994. Tasmanian Devils are popular with domestic and international tourists.
The Tasmanian Devil is probably best known internationally as the inspiration for a Looney Tunes character The Tasmanian Devil or "Taz". The only similarity between the Tasmanian Devil and its cartoon incarnation is a voracious appetite. There is a mutant mouse called Tasmanian Devil that is defective in the development of sensory hair cells of the ear, the mutant has abnormal behaviours including head-tossing and circlingTemplate:Mn much like the cartoon "Taz" rather than the Tasmanian Devil.