The document describes the characteristics of the animal kingdom. It discusses that animals are multicellular, eukaryotic organisms without cell walls that develop from a zygote into a gastrula with three germ layers. It then describes the 8 invertebrate phyla including sponges, cnidarians, flatworms, roundworms, mollusks, annelids, echinoderms, and arthropods. Finally, it discusses the subphylum of vertebrates within the phylum chordata.