Animals that belong to phylum chordate are bilaterally symmetric, triploblastic and coelmate. The other important features of this group are given below.
Nerve cord: nerve cord is a long chord made of nerve fibers which runs along the length of animal’s body. In non- chordates it is ventral in its position but in chordates it is dorsal, hollow and tubular.
Notochord: Presence of notochord is the peculiar feature of phylum chordate. ‘Noto’ means back and ‘chord’ means string- The notochord is a long rod-like support structure that runs along back of the animal separating the nervous tissue from the gut. It is located ventral to nerve cord and is replaced by bone or cartilage to from a vertebral column in higher vertebrates.
It provides a place for muscles to attach for ease of movement. In higher vertebrates is replaced by a vertebral column which is made up of bone or cartilage.
Gill slits: Paired gill-slits in the pharynx.
Post anal tail: A post anal tail is present always or at any stage of life [like in embryonic, larval, adult stage].
Ventral heart: A well developed close circulatory system is present with a ventral heart and blood vessels.
Endoskeleton: a bony or cartilaginous endoskeleton is present in higher vertebrates.
Body temperature: depending on the body temperature, organisms may be cold blooded or warm blooded, i.e., their body temperature may remain constant or it may vary with change in surrounding temperature.
Reproduction: these organisms always reproduce by sexual mode but the fertilization and development varies among them.
