When Does a Tadpole Become a Frog?
Frogs’ eggs become tadpoles within two weeks of being laid in the water, but tadpoles may take anything from two months to three years to change completely into frogs. The time taken seems to depend on the environment. Tadpoles will generally develop faster in warmer waters.
Also the more advanced species of frog have simplified and shortened the process of transformation. Tadpoles, like fish breathe through gills. They develop lungs during the change-over, gain legs and lose their tails. Their diet changes, too-tadpoles live on plants in the pond, but frogs live on very small insects.
As a tadpole matures, it most commonly metamorphosis’s by gradually growing limbs (usually the back legs first, followed by the front legs) and then (most commonly in the case of frogs) outwardly absorbing its tail by apoptosis. Lungs develop around the time of leg development, and tadpoles late in development will often be found near the surface of the water, where they breathe air.
During the final stages of external metamorphosis, the tadpole’s mouth changes from a small, enclosed mouth at the front of the head to a large mouth the same width as the head. The intestines shorten to accommodate the new diet. Most tadpoles are herbivorous, subsisting on algae and plants. Some species are omnivorous, eating detritus and, when available, smaller tadpoles.
Tadpoles vary greatly in size, both during their development and between species. For example, in a single family, Megophryidae, length of late-stage tadpoles varies between 33 millimeters (1.3 in) and 106 millimeters (4.2 in). The tadpoles of Pseudis paradoxa grow to 25 centimeters (9.8 in), the largest of any frog.