 Tadpoles retain the lateral line system of their ancestral fishes , but this is lost in terrestrial adult amphibians . Some caecilians possess electroreceptors that allow them to locate objects around them when submerged in water . The ears are well developed in frogs . There is no external ear , but the large circular eardrum lies on the surface of the head just behind the eye . This vibrates and sound is transmitted through a single bone , the stapes , to the inner ear . Only high @-@ frequency sounds like mating calls are heard in this way , but low @-@ frequency noises can be detected through another mechanism . There is a patch of specialized <unk> , called papilla amphibiorum , in the inner ear capable of detecting deeper sounds . Another feature , unique to frogs and salamanders , is the columella @-@ operculum complex adjoining the auditory capsule which is involved in the transmission of both airborne and seismic signals . The ears of salamanders and caecilians are less highly developed than those of frogs as they do not normally communicate with each other through the medium of sound . 
