They breathe through unseen holes in their heads. You may only see them with a microscope.
Different amino acids means difference DNA sequences, which means they are distantly related.
Further understanding: if you look at identical twins, they are closely related to each other because they have almost the same DNA, which will code for the same amino acids, which will lead to the same phenotype or appearance.
To summarize, the greater the amino acid differences the less related they are and vice versa
Hope that helps
Pythons have jaws that are connected by flexible ligaments so they can stretch around large prey and then swallow it.
When the sea floor spreads or collides it creates breakages which would be ocean ridges and deep sea trenches