There's a reason you never see antacid advertisements at the bottom of the ocean. Well, there are probably several reasons, but one no doubt is due to the fact that some aquatic creatures have a more efficient way of dealing with upset stomachs. These animals simply rinse their stomachs in the water similar to how people wash their socks.
In the most detailed study yet of the process, researchers at Aberdeen University in Scotland found that Thornback Stingrays literally turn their stomachs inside out to rid themselves of toxic or indigestible matter. First a ray will push its stomach up through its mouth. Then, with its stomach hanging out like a tongue, the ray will thrash its head back and forth in order dislodge every last particle consumed. Once clean, the stomach then disappears back inside the ray.
The process takes a total of about four seconds from start to finish and is also known to be favored by other ray species and certain sharks, frogs, and toads. The Aberdeen researchers published their findings recently in the journal Nature.