The caterpillar, which is the larval stage of a butterfly, is very different from its adult form. which phenomenon is responsible for this difference ?

The image shows embryos of three vertebrate classes

Up until 1938, paleontologists accepted the idea that coelacanths (an ancient fish) went extinct at the time that they last appear in the fossil record, about 80 million years ago. but in 1938, a live coelacanth was discovered off the coast of south africa that was compared to the fossil record and found to be the same species what goal of science does this discovery represent

Need with these questions . need the answers in a rush for these questions are the answers i put down are correct or not? ?