Tree frogs use their eyeballs to help them swallow food.

This unique biological mechanism is known as eye-mediated swallowing and is common among many anuran species. Research conducted by scientists like Richard Deban at the University of South Florida has shown that frogs pull their eyes into the space of the oropharyngeal cavity. Because frogs lack a hard palate or a rib cage to create the internal pressure needed for swallowing, they rely on this mechanical force.During the swallowing process, the levator bulbi muscles relax while the retractor bulbi muscles contract. This action pulls the globes of the eyes downward through openings in the skull called the interpterygoid vacuities. As the eyes descend, they press against the bolus of food, effectively acting as a biological piston to drive the prey into the esophagus.A study published in the Journal of Experimental Biology observed that if a frog is prevented from retracting its eyes, the number of gulps required to swallow increases significantly. In some species, the eyes can retract up to 5 millimeters or more depending on the size of the frog. This adaptation is essential for consuming large insects or slippery prey that might otherwise escape or remain stuck in the mouth.This evolutionary trait highlights the multifunctional nature of the amphibian eye, which serves both as a visual organ and a digestive tool. It allows tree frogs to maintain a lightweight skeletal structure while still being able to consume relatively large meals. This process is nearly instantaneous and happens every time the frog successfully captures prey with its tongue.