This Chinese turtle urinates through its mouth

Ip found that just 6 percent of the urea that the turtles produces was ejected via their kidneys. The rest came out through the mouth. When Ip gave the turtles a chance to dip their heads in water, he found that they can sit there sucking, swilling, and spitting out the liquid for up to 100 minutes. This oral route gets rid of urea between 15 and 50 times faster than the kidneys.

Fish share the same trick -- they too can get rid of urea through their gills. But why is this turtle the only other back-boned animal that does so? Ip thinks the answer lies in its salty habitat. To urinate through the normal kidney route, the turtle would need to constantly drink more water to make up for what it lost. And because the surrounding water is so salty, they would soon build up toxic levels in their bodies (especially since reptile kidneys are atrocious at getting rid of unwanted salts).

The Chinese soft-shell has evolved to deal with this problem through oral urination. It doesn't need to drink anything. It just gargles some surrounding water and spits out its urine.

Nota bene: Previously, previously, previously, previously, previously, previously.