Editing Metamorphosis (section)

==== Frogs and toads ====
With frogs and toads, the  external gills of the newly hatched tadpole are covered with a gill sac after a few days, and lungs are quickly formed. Front legs are formed under the gill sac, and hindlegs are visible a few days later. Following that there is usually a longer stage during which the tadpole lives off a vegetarian diet. Tadpoles use a relatively long, spiral‐shaped gut to digest that diet. Recent studies suggest tadpoles do not have a balanced homeostatic feedback control system until the beginning stages of metamorphosis. At this point, their long gut shortens and begins favoring the diet of insects.<ref>{{Cite journal|last=Bender|first=Melissa|date=March 28, 2018|title=To eat or not to eat: ontogeny of hypothalamic feeding controls and a role for leptin in modulating life-history transition in amphibian tadpoles|journal= Proceedings of the Royal Society B: Biological Sciences|volume=285|issue=1875 |doi=10.1098/rspb.2017.2784 |pmid=29593109 |pmc=5897637 |s2cid=4853293 }}</ref>

Rapid changes in the body can then be observed as the lifestyle of the frog changes completely. The spiral‐shaped mouth with horny tooth ridges is resorbed together with the spiral gut. The animal develops a big jaw, and its gills disappear along with its gill sac. Eyes and legs grow quickly, a tongue is formed, and all this is accompanied by associated changes in the neural networks (development of stereoscopic vision, loss of the lateral line system, etc.) All this can happen in about a day. It is not until a few days later that the tail is reabsorbed, due to the higher thyroxin concentrations required for tail resorption.<ref>{{Cite web |date=2021-01-13 |title=15.2: The Life Cycle of Amphibians |url=https://bio.libretexts.org/Courses/Lumen_Learning/Fundamentals_of_Biology_I_(Lumen)/15:_Module_12-_Vertebrates/15.02:_The_Life_Cycle_of_Amphibians |access-date=2025-01-24 |website=Biology LibreTexts |language=en}}</ref>
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