How a frog turns its stomach inside out
In some frogs, expelling an unpleasant meal can involve gastric eversion: the stomach itself is pushed up through the mouth and turned inside out. It is a dramatic form of clearing the stomach, not simply ordinary vomiting, in which food travels back up while the organ stays in place.
The stomach is a flexible muscular sac connected to the digestive tract. During eversion, the frog brings the sac out through its mouth; its front feet help strip away food clinging to the exposed surface. The stomach can then be drawn back into the body and resume its usual position.
A way to get rid of more than a bad bite
This maneuver gives a frog a way to remove material from the stomach when it needs to reject what it has swallowed. Turning the organ outward exposes its inner surface, so food can be scraped away rather than left behind. The behavior is unusual among vertebrates, but it fits a frog’s practical problem: prey and other swallowed material may be difficult to handle once they are already inside.
The memorable part is also the functional one: the frog temporarily brings the surface that normally handles digestion out into the open, cleans it, and pulls it back in.
