Gastric Eversion: A Frog's Surprising Defence

The animal kingdom is full of fascinating and strange defence mechanisms. One of the most unusual is gastric eversion, employed by some species of frogs.

This is a form of defence where the frog literally vomits up its entire stomach contents in response to extreme stress or danger. This isn’t a simple regurgitation. The frog pushes its entire stomach out through its mouth, turns it inside out, and uses its forearms to scrape away any potentially harmful substances.

How Does Gastric Eversion Work?

The process of gastric eversion can be broken down into several steps:

• Reaction to Poison or Predators: When a frog consumes something toxic, or encounters a predator, it may trigger gastric eversion. The frog’s stomach completely extends out of its mouth, looking like a balloon. This helps expel any harmful material it may have eaten or startle a predator with the surprising action.
• Self-Cleaning Stomach: Unlike mammals, frogs can’t regurgitate, so gastric eversion is their method of self-cleaning. After the stomach is everted, the frog uses its front limbs to scrape away residue from the stomach lining. It then pulls the stomach back into place.
• Quick Recovery: As intense as it sounds, frogs can recover quickly from gastric eversion. Once the stomach is retracted, normal function resumes within a short time. However, repeated eversion can have a negative impact on their energy and health.
• Not Common to All Frogs: Gastric eversion is rare and only occurs in certain frog species. Because it requires a lot of energy and exposes the frog to other risks while the stomach is everted, it is typically a last resort.

Why Do Frogs Use Gastric Eversion?

This behaviour is a unique survival adaptation. It helps frogs remove toxins or deal with unpalatable or dangerous prey. By getting rid of the toxin, the frog increases its chances of survival, even if the process is dramatic and leaves it temporarily vulnerable.

In conclusion, gastric eversion in frogs is a fascinating and extreme defence mechanism. It shows the variety and adaptability of defence strategies in the animal kingdom.