Researchers have discovered that aggressive Tasmanian devils carry a greater risk of getting the fatal tumor disease, which threatens to wipe out the species.
A University of Tasmania study which looked at more than 300 devils for four years found that biting puts aggressive devils at risk of contracting the disease.
There are four strains of the disease which has wiped out 85 per cent of the population. The study also found that most tumors were present in the devils' mouths.
Less virulent strains of the tumor are not as dangerous and they permit devils to survive longer.