|Notes: Chordates Introduction|
The following adaptations are present in all chordates: notochord, dorsal hollow nerve cord, pharyngeal slits and a muscular postanal tail. A notochord is a primitive backbone. The hollow nerve cord develops from the ectoderm and then rolls into a tube right below the notochord. Pharyngeal slits filter food(or oxygen in fishes) from water: the chordate gulps in water through its mouth (or analogous structure) water passes through tiny slits in a membrane filtering out large particles that are most likely food. Most nonchordates have a digestive tract running the entire length of their bodies.