Which of the following is $NOT$ found in vertebrate animals?

In which of the following is the notochord absent?

All vertebrates are chordates but all chordates are not vertebrates. Explain.

Which of the following is a characteristic of chordates that is $NOT$ found in non-chordates?

Which of the following statements are true for the phylum $Chordata$?
$(a)$ In $Urochordata$,the notochord extends from head to tail and is present throughout their life.
$(b)$ In $Vertebrata$,the notochord is present during the embryonic period only.
$(c)$ The central nervous system is dorsal and hollow.
$(d)$ $Chordata$ is divided into $3$ subphyla: $Hemichordata$,$Tunicata$,and $Cephalochordata$.

In which of the following is the notochord extended from head to tail region and is persistent throughout their life?