Answer:
Notochord is present throughout their lives.
Explanation:
Within the phylum of the chordates there are three subphylum. Cephalochordates, Urocordated and Vertebrates. Unlike the others, in the cephalochordates the notochord is present throughout its life, this extends dorsally from the tail to the head. The cephalochordates are considered primitive animals, live in marine waters and they feed by filtering.
