Major changes take place in tadpole's digestive and circulatory systems during metamorphosis Why do you think these changes are necessary? is...

Tadpoles begin their life in water. Essentially, their
diet is that of an herbivore and they consume algae in the pond. However, some may be
carnivorous. This reduces competition between the juvenile tadpole and the adult frog.
The adult's diet is that of a carnivore. Adaptations like their tongue which is an
appendage used to capture food like insects, their maxillary teeth, which helps to hold
and grind their prey, are all useful to fulfilling the niche of a carnivore. Therefore,
the digestive systems are hydrolyzing different substrates with their enzymes and are
different. The circulation in the adult frog needs to be able to supply blood to an
active organism that can both swim, jump long distances, etc. Therefore, there has to be
a more efficient method of circulation for the adult frog. Both can obtain respiratory
gases through their moist skin, and there are blood vessels to help circulate oxygen
below the skin. However, lungs are present in adult frogs which help breathe oxygen on
land. A tadpole has a loop circulatory system and the adult frog has a more complex
circulatory system with a three chambered heart. This helps keep oxygenated and
deoxygenated blood somewhat separate, although there is a mix in the ventricle. But, it
enables adult frogs to be much more active than the juveniles.