Set apart from lower animals by several
distinguishing characteristics in addition to having a notochord. First, all
chordate embryos have the three primary germ layers from which all specialized
tissues and organs develop. Second, chordates are bilaterally symmetrical
animals with anterior-posterior differentiation. Third, the body has a true
coelom and a digestive tract that begins with a mouth and ends with an anus.
Other characteristics that differentiate the chordates from other animals are
the presence of pharyngeal gill slits and the dorsal hollow nerve cord.
