The purpose of a frog's eustachian tube is to allow the frog to hear and to equalize the pressure inside of the frog's inner ear, reports Biology Corner. Humans and many other animals also have eustachian tubes for these same purposes.
Many adolescents in biology classes across the world will dissect a frog and look for not only its eustachian tube, but also its esophagus, glottis, tongue, vomerine teeth, maxillary teeth and internal nares. When dissecting the frog, the eustachian tubes can be seen by opening the frog's mouth. The are located on either side of the esophagus. The esophagus is what allows the frog to swallow its food as it delivers food to the stomach.