What is Metamorphosis? A typically marked or more or less abrupt developmental change in the form or structure of an animal occuring subsequent to birth or hatching
How does it Work? Metamorphosis in amphibians is regulated by thyroxin and prolactin Development is subject to many adaptations due to specific ecological circumstances They also make use of the lateral line organ Redundant organs are reabsorbed via apoptosis after metamorphosis
The Egg The egg begins as a single cell It becomes surrounded by a jellylike covering, which protects the egg The female may or may not stay with the eggs to take care of the young after she had laid them
The Embyo The mass of cells in the egg come to form an embryo Organs and gills begin to form, and the embryo lives off the internal yolk This supplies it with nutrients for 21 days
The Tadpole After its 21 day development period, the embryo leaves its jelly shell, and attaches itself to a weed in the water It has external gills like a fish to absorb oxygen and feeds on algae It is extremely vulnerable, and must rely on its camouflage to protect it
The Changing Tadpole About five weeks, the tadpole begins to change It starts to grow hind legs, which are soon followed with forelegs Lungs begin to develop, preparing the frog for its life on land
The Froglet Over time, the tadpole becomes even more froglike Its mouth widens, it loses its horny jaws, gills are lost The tail becomes much smaller, and the legs grow The lungs are almost functioning at this point
The Frog Eleven weeks after the egg was laid, a fully developed frog with lungs, legs, and no tail emerges from the water Eventually, it finds a mate The female lays the eggs, the male fertilizes them, and the whole process begins again
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