For example, the phylum [[Chordata]] includes all of the vertebrates: mammals, birds, fish, frogs, and many others—most of what we commonly think of as animals. Despite the enormous variety, almost all chordates have backbones, a nervous system, a heart, and bilateral symmetry. | For example, the phylum [[Chordata]] includes all of the vertebrates: mammals, birds, fish, frogs, and many others—most of what we commonly think of as animals. Despite the enormous variety, almost all chordates have backbones, a nervous system, a heart, and bilateral symmetry. |