Because it contains animals with a backbone, or vertabrates.
The phylum Chordata is a taxonomic group including all animals with spinal cords, a group also known as vertebrates. In general, a phylum is a group of species which are loosely related to one...
Sharks and rays
Yes. The animals in the Phlum Chordata have spinal cords (which are bones).
Because when we were still developing inside our mothers, we developed gills. I forgot why though, sorry.