Owls are in fact classified as vertebrates because of the fact that they have a back bone or spine. Any creature that has a spine is automatically labeled a vertebrate, including birds like owls. These animals along with other vertebrates are all put into the subphylum of vertebrae which are chordates with back bones as well as spines.
There are many different kinds of owls which live in places all over the world and each one is considered to be a vertebrate, simply because they have a spine as well as a back bone. This is really the only qualifier needed for an animal to be classified under the vertebrae subphylum.
holly says
owls are cool