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Planet Earth

Bat Spit


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The sugary, acidic diet of a fruit bat would corrode the teeth of just about any other mammal. But fruit bats, like this one shown devouring a fig, don’t have problems with tooth decay. Anatomist Elizabeth Dumont of Northeastern Ohio Universities College of Medicine thought that the saliva of fruit bats might buffer the acids in their food, thus protecting their teeth. To find out, she measured the acidity of saliva from a number of species of fruit bat. In some bats the pH dropped close to 5.5, the acidity at which human teeth begin to decay. To Dumont’s surprise, the saliva of some old-world fruit bats was just as acidic after their food had cleared the mouth and digestive system, 20 minutes later, and remained so for six hours. She isn’t sure why the bats’ teeth don’t rot, but she thinks the acidity of their saliva may help bats extract all the nutrients they can from their food. Fruit is a low-quality food, Dumont says, so the bats draw a little more food out in the short 20 minutes they have to get it.

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