Pollution masks for rats

According to a new study, mole rats often use wood as a "pollution mask" to avoid breathing fine dust. The mole rats, Heterocephalus glaber, place a wood shaving or tuber husk between their lips and protruding teeth. Paul Sherman of Cornell University in Ithaca, New York, and his colleagues found that most mole rats do this when gnawing on plastic, which breaks into fine dust. But they do not bother when gnawing materials which split into sizeable chunks. "They assess the material they are going to chew on," says Sherman. The researchers say that these wood shavings stop fine dust from choking the animals.