The thick, waterproof fur that once made the platypus (Ornithorhynchus anatinus) a valuable target for trappers may soon present another danger for the unique mammal: Australia could soon end up being too hot for the species to survive.

Platypus fur is so warm and watertight that it insulates the semiaquatic animals from virtually all heat loss—an important function, because platypus spend up to 10 hours a day in 0 degree Celsius streams and rivers. But this evolutionary advantage puts the species at a disadvantage as climate change heats things up in Australia. Research published online this week in Global Change Biology predicts that more than 30 percent of current platypus habitat will become too warm for the species by 2070.

According to the Web site Climate Change in Australia, models show a surface temperature rise of up to 5 degrees Celsius by 2070 in the Australian states of New South Wales, Queensland and Victoria, where platypus are found.

"The highly insulating fur is an asset for surviving in cooler climates but becomes a liability in warmer conditions," co-author Jenny Davis, a lecturer and ecologist at Australia's Monash University, told BBC News.

Davis and her team studied two centuries' worth of platypus distribution records, which were then combined with models of rainfall and temperature. The analysis revealed that until the 1960s platypus habitat was mostly determined by the amount of rainfall an area received. After that time the animals disappeared from areas where general temperatures had risen.

Davis says this research indicates the need to maintain not just the presence of aquatic habitats, but also their current temperatures.

Platypus were hunted for the fur trade until the early 20th century, but they are now protected under Australian law. The evolutionarily unique animals are one of five egg-laying mammal species. They are also the sole living member of their genus and one of world's only venomous mammals.

Photo courtesy of Melbourne Water via Flickr. Used under Creative Commons license