To give an analogy of an atom; If the whole atom was a large football stadium then the nucleus would be a soccer ball at the center of the pitch in the stadium, with electrons (that hold negligible mass) skimming about in the empty space. This center ball carried most of the mass of the atom. Therefore most matter that you see is actually and ironically empty space.
The kingdom Animalia, or Metazoa, includes all animals. Animals are multicellular, eukaryotic organisms, which are heterotrophic, meaning they obtain nutrition from organic sources.
