From RTAW Reefpedia
All chordates have the following characteristics at some point in their life, even if only during embryo stages;
- pharyngeal slits – a series of openings that connect the inside of the throat to the outside of the neck. These often but not always become gills.
- dorsal nerve cord – a bundle of nerve fibers that run down the back, connecting the brain with muscles and other organs.
- notochord – a cartilaginous rod running underneath and supporting the nerve cord.
- post-anal tail – an extention of the body past the anal opening.
- Urochordata - sometimes know as Tunicata or Sea Squirts.  Animals that have vertebrae in early development, but it is no longer present after full development.
- Vertebrata - animals that have vertebrae
- (http://www.ucmp.berkeley.edu/): University of California Museum of Paleontology, Regents of the University of California, 1994 -2001.