How do insects breathe? Do ants even breathe? If they don't, how do they stay alive? On what resources do they depend upon to stay alive? How are they different form mammals?

Insects breathe by simple diffusion through the cell walls. They do not breathe in the same sense that we humans do. They intake oxygen through spiracles in the insect's cuticle. It goes through the insect's trachea by dissolving into the tracheal liquid. From there it diffuses throughout the insect in tracheal tubes. At the ends of the tubes, the oxygen is taken by body cells.