 At metamorphosis , rapid changes in the body take place as the lifestyle of the frog changes completely . The spiral ‐ shaped mouth with horny tooth ridges is reabsorbed together with the spiral gut . The animal develops a large jaw , and its gills disappear along with its gill sac . Eyes and legs grow quickly , and a tongue is formed . There are associated changes in the neural networks such as development of stereoscopic vision and loss of the lateral line system . All this can happen in about a day . A few days later , the tail is reabsorbed , due to the higher thyroxine concentration required for this to take place . 
