Chordates are members of the Phylum Chordata. At some point of time in their life cycle, they possess a stiff, dorsal supporting rod. Another characteristic of Chordates is a tail that extends behind and above the anus. They also have Pharyngeal slits, which are series of openings that connect the inside of the throat to the outside of the "neck". These are often used as gills, but not always. They have a dorsal nerve cord, which is a bundle of nerve fibers that run down the "back". It connects the brain to lateral muscles and other organs. Finally, they have a notochord, which is a cartilaginous rod that runs underneath and supports the nerve cord.