Birds are a group of warm-blooded vertebrates constituting the class Aves (/ΛeΙͺviΛz/), characterized by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton.
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia (/ΛΓ¦nΙͺΛmΙΛliΙ/[4]). With few exceptions, animals consume organic material, breathe oxygen, have myocytes and are able to move, can reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development. Animals form a clade, meaning that they arose from a single common ancestor.