Talk about having a potty mouth. When Chinese soft-shelled turtles (Pelodiscus sinensis) need to relieve themselves, they just open wide, according to a study published online today in The Journal of Experimental Biology. The reptiles don't have gills, but they have structures in their mouths that work a little like gills. That means they have the option of breathing underwater. But normally they just reach up and breathe air. So researchers thought it was a little odd that, when the turtles were on dry land, they would stick their heads in puddles and swish water around in their mouths. The scientists thought maybe something else was going on besides respiration, so they bought Chinese soft-shelled turtles at a market in Singapore and found ways to collect their urine, like attaching a flexible latex tube to each one's underside. They found that the animals were getting rid of the vast majority of their urea, a major component of urine, through their mouths instead of their hind ends. The team speculates that this might be because animals have to drink a lot of water to make urine, which can be unhealthy in the saltier waters where these turtles spend some of their time. If they're just rinsing the water around in their mouths, they avoid having to get rid of all that salt.

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